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Article Contents

Introduction, 1 installed capacity and application of solar energy worldwide, 2 the role of solar energy in sustainable development, 3 the perspective of solar energy, 4 conclusions, conflict of interest statement.

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Solar energy technology and its roles in sustainable development

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Ali O M Maka, Jamal M Alabid, Solar energy technology and its roles in sustainable development, Clean Energy , Volume 6, Issue 3, June 2022, Pages 476–483, https://doi.org/10.1093/ce/zkac023

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Solar energy is environmentally friendly technology, a great energy supply and one of the most significant renewable and green energy sources. It plays a substantial role in achieving sustainable development energy solutions. Therefore, the massive amount of solar energy attainable daily makes it a very attractive resource for generating electricity. Both technologies, applications of concentrated solar power or solar photovoltaics, are always under continuous development to fulfil our energy needs. Hence, a large installed capacity of solar energy applications worldwide, in the same context, supports the energy sector and meets the employment market to gain sufficient development. This paper highlights solar energy applications and their role in sustainable development and considers renewable energy’s overall employment potential. Thus, it provides insights and analysis on solar energy sustainability, including environmental and economic development. Furthermore, it has identified the contributions of solar energy applications in sustainable development by providing energy needs, creating jobs opportunities and enhancing environmental protection. Finally, the perspective of solar energy technology is drawn up in the application of the energy sector and affords a vision of future development in this domain.

With reference to the recommendations of the UN, the Climate Change Conference, COP26, was held in Glasgow , UK, in 2021. They reached an agreement through the representatives of the 197 countries, where they concurred to move towards reducing dependency on coal and fossil-fuel sources. Furthermore, the conference stated ‘the various opportunities for governments to prioritize health and equity in the international climate movement and sustainable development agenda’. Also, one of the testaments is the necessity to ‘create energy systems that protect and improve climate and health’ [ 1 , 2 ].

The Paris Climate Accords is a worldwide agreement on climate change signed in 2015, which addressed the mitigation of climate change, adaptation and finance. Consequently, the representatives of 196 countries concurred to decrease their greenhouse gas emissions [ 3 ]. The Paris Agreement is essential for present and future generations to attain a more secure and stable environment. In essence, the Paris Agreement has been about safeguarding people from such an uncertain and progressively dangerous environment and ensuring everyone can have the right to live in a healthy, pollutant-free environment without the negative impacts of climate change [ 3 , 4 ].

In recent decades, there has been an increase in demand for cleaner energy resources. Based on that, decision-makers of all countries have drawn up plans that depend on renewable sources through a long-term strategy. Thus, such plans reduce the reliance of dependence on traditional energy sources and substitute traditional energy sources with alternative energy technology. As a result, the global community is starting to shift towards utilizing sustainable energy sources and reducing dependence on traditional fossil fuels as a source of energy [ 5 , 6 ].

In 2015, the UN adopted the sustainable development goals (SDGs) and recognized them as international legislation, which demands a global effort to end poverty, safeguard the environment and guarantee that by 2030, humanity lives in prosperity and peace. Consequently, progress needs to be balanced among economic, social and environmental sustainability models [ 7 ].

Many national and international regulations have been established to control the gas emissions and pollutants that impact the environment [ 8 ]. However, the negative effects of increased carbon in the atmosphere have grown in the last 10 years. Production and use of fossil fuels emit methane (CH 4 ), carbon dioxide (CO 2 ) and carbon monoxide (CO), which are the most significant contributors to environmental emissions on our planet. Additionally, coal and oil, including gasoline, coal, oil and methane, are commonly used in energy for transport or for generating electricity. Therefore, burning these fossil fuel s is deemed the largest emitter when used for electricity generation, transport, etc. However, these energy resources are considered depleted energy sources being consumed to an unsustainable degree [ 9–11 ].

Energy is an essential need for the existence and growth of human communities. Consequently, the need for energy has increased gradually as human civilization has progressed. Additionally, in the past few decades, the rapid rise of the world’s population and its reliance on technological developments have increased energy demands. Furthermore, green technology sources play an important role in sustainably providing energy supplies, especially in mitigating climate change [ 5 , 6 , 8 ].

Currently, fossil fuels remain dominant and will continue to be the primary source of large-scale energy for the foreseeable future; however, renewable energy should play a vital role in the future of global energy. The global energy system is undergoing a movement towards more sustainable sources of energy [ 12 , 13 ].

Power generation by fossil-fuel resources has peaked, whilst solar energy is predicted to be at the vanguard of energy generation in the near future. Moreover, it is predicted that by 2050, the generation of solar energy will have increased to 48% due to economic and industrial growth [ 13 , 14 ].

In recent years, it has become increasingly obvious that the globe must decrease greenhouse gas emissions by 2050, ideally towards net zero, if we are to fulfil the Paris Agreement’s goal to reduce global temperature increases [ 3 , 4 ]. The net-zero emissions complement the scenario of sustainable development assessment by 2050. According to the agreed scenario of sustainable development, many industrialized economies must achieve net-zero emissions by 2050. However, the net-zero emissions 2050 brought the first detailed International Energy Agency (IEA) modelling of what strategy will be required over the next 10 years to achieve net-zero carbon emissions worldwide by 2050 [ 15–17 ].

The global statistics of greenhouse gas emissions have been identified; in 2019, there was a 1% decrease in CO 2 emissions from the power industry; that figure dropped by 7% in 2020 due to the COVID-19 crisis, thus indicating a drop in coal-fired energy generation that is being squeezed by decreasing energy needs, growth of renewables and the shift away from fossil fuels. As a result, in 2020, the energy industry was expected to generate ~13 Gt CO 2 , representing ~40% of total world energy sector emissions related to CO 2 . The annual electricity generation stepped back to pre-crisis levels by 2021, although due to a changing ‘fuel mix’, the CO 2 emissions in the power sector will grow just a little before remaining roughly steady until 2030 [ 15 ].

Therefore, based on the information mentioned above, the advantages of solar energy technology are a renewable and clean energy source that is plentiful, cheaper costs, less maintenance and environmentally friendly, to name but a few. The significance of this paper is to highlight solar energy applications to ensure sustainable development; thus, it is vital to researchers, engineers and customers alike. The article’s primary aim is to raise public awareness and disseminate the culture of solar energy usage in daily life, since moving forward, it is the best. The scope of this paper is as follows. Section 1 represents a summary of the introduction. Section 2 represents a summary of installed capacity and the application of solar energy worldwide. Section 3 presents the role of solar energy in the sustainable development and employment of renewable energy. Section 4 represents the perspective of solar energy. Finally, Section 5 outlines the conclusions and recommendations for future work.

1.1 Installed capacity of solar energy

The history of solar energy can be traced back to the seventh century when mirrors with solar power were used. In 1893, the photovoltaic (PV) effect was discovered; after many decades, scientists developed this technology for electricity generation [ 18 ]. Based on that, after many years of research and development from scientists worldwide, solar energy technology is classified into two key applications: solar thermal and solar PV.

PV systems convert the Sun’s energy into electricity by utilizing solar panels. These PV devices have quickly become the cheapest option for new electricity generation in numerous world locations due to their ubiquitous deployment. For example, during the period from 2010 to 2018, the cost of generating electricity by solar PV plants decreased by 77%. However, solar PV installed capacity progress expanded 100-fold between 2005 and 2018. Consequently, solar PV has emerged as a key component in the low-carbon sustainable energy system required to provide access to affordable and dependable electricity, assisting in fulfilling the Paris climate agreement and in achieving the 2030 SDG targets [ 19 ].

The installed capacity of solar energy worldwide has been rapidly increased to meet energy demands. The installed capacity of PV technology from 2010 to 2020 increased from 40 334 to 709 674 MW, whereas the installed capacity of concentrated solar power (CSP) applications, which was 1266 MW in 2010, after 10 years had increased to 6479 MW. Therefore, solar PV technology has more deployed installations than CSP applications. So, the stand-alone solar PV and large-scale grid-connected PV plants are widely used worldwide and used in space applications. Fig. 1 represents the installation of solar energy worldwide.

Installation capacity of solar energy worldwide [ 20 ].

1.2 Application of solar energy

Energy can be obtained directly from the Sun—so-called solar energy. Globally, there has been growth in solar energy applications, as it can be used to generate electricity, desalinate water and generate heat, etc. The taxonomy of applications of solar energy is as follows: (i) PVs and (ii) CSP. Fig. 2 details the taxonomy of solar energy applications.

The taxonomy of solar energy applications.

Solar cells are devices that convert sunlight directly into electricity; typical semiconductor materials are utilized to form a PV solar cell device. These materials’ characteristics are based on atoms with four electrons in their outer orbit or shell. Semiconductor materials are from the periodic table’s group ‘IV’ or a mixture of groups ‘IV’ and ‘II’, the latter known as ‘II–VI’ semiconductors [ 21 ]. Additionally, a periodic table mixture of elements from groups ‘III’ and ‘V’ can create ‘III–V’ materials [ 22 ].

PV devices, sometimes called solar cells, are electronic devices that convert sunlight into electrical power. PVs are also one of the rapidly growing renewable-energy technologies of today. It is therefore anticipated to play a significant role in the long-term world electricity-generating mixture moving forward.

Solar PV systems can be incorporated to supply electricity on a commercial level or installed in smaller clusters for mini-grids or individual usage. Utilizing PV modules to power mini-grids is a great way to offer electricity to those who do not live close to power-transmission lines, especially in developing countries with abundant solar energy resources. In the most recent decade, the cost of producing PV modules has dropped drastically, giving them not only accessibility but sometimes making them the least expensive energy form. PV arrays have a 30-year lifetime and come in various shades based on the type of material utilized in their production.

The most typical method for solar PV desalination technology that is used for desalinating sea or salty water is electrodialysis (ED). Therefore, solar PV modules are directly connected to the desalination process. This technique employs the direct-current electricity to remove salt from the sea or salty water.

The technology of PV–thermal (PV–T) comprises conventional solar PV modules coupled with a thermal collector mounted on the rear side of the PV module to pre-heat domestic hot water. Accordingly, this enables a larger portion of the incident solar energy on the collector to be converted into beneficial electrical and thermal energy.

A zero-energy building is a building that is designed for zero net energy emissions and emits no carbon dioxide. Building-integrated PV (BIPV) technology is coupled with solar energy sources and devices in buildings that are utilized to supply energy needs. Thus, building-integrated PVs utilizing thermal energy (BIPV/T) incorporate creative technologies such as solar cooling [ 23 ].

A PV water-pumping system is typically used to pump water in rural, isolated and desert areas. The system consists of PV modules to power a water pump to the location of water need. The water-pumping rate depends on many factors such as pumping head, solar intensity, etc.

A PV-powered cathodic protection (CP) system is designed to supply a CP system to control the corrosion of a metal surface. This technique is based on the impressive current acquired from PV solar energy systems and is utilized for burying pipelines, tanks, concrete structures, etc.

Concentrated PV (CPV) technology uses either the refractive or the reflective concentrators to increase sunlight to PV cells [ 24 , 25 ]. High-efficiency solar cells are usually used, consisting of many layers of semiconductor materials that stack on top of each other. This technology has an efficiency of >47%. In addition, the devices produce electricity and the heat can be used for other purposes [ 26 , 27 ].

For CSP systems, the solar rays are concentrated using mirrors in this application. These rays will heat a fluid, resulting in steam used to power a turbine and generate electricity. Large-scale power stations employ CSP to generate electricity. A field of mirrors typically redirect rays to a tall thin tower in a CSP power station. Thus, numerous large flat heliostats (mirrors) are used to track the Sun and concentrate its light onto a receiver in power tower systems, sometimes known as central receivers. The hot fluid could be utilized right away to produce steam or stored for later usage. Another of the great benefits of a CSP power station is that it may be built with molten salts to store heat and generate electricity outside of daylight hours.

Mirrored dishes are used in dish engine systems to focus and concentrate sunlight onto a receiver. The dish assembly tracks the Sun’s movement to capture as much solar energy as possible. The engine includes thin tubes that work outside the four-piston cylinders and it opens into the cylinders containing hydrogen or helium gas. The pistons are driven by the expanding gas. Finally, the pistons drive an electric generator by turning a crankshaft.

A further water-treatment technique, using reverse osmosis, depends on the solar-thermal and using solar concentrated power through the parabolic trough technique. The desalination employs CSP technology that utilizes hybrid integration and thermal storage allows continuous operation and is a cost-effective solution. Solar thermal can be used for domestic purposes such as a dryer. In some countries or societies, the so-called food dehydration is traditionally used to preserve some food materials such as meats, fruits and vegetables.

Sustainable energy development is defined as the development of the energy sector in terms of energy generating, distributing and utilizing that are based on sustainability rules [ 28 ]. Energy systems will significantly impact the environment in both developed and developing countries. Consequently, the global sustainable energy system must optimize efficiency and reduce emissions [ 29 ].

The sustainable development scenario is built based on the economic perspective. It also examines what activities will be required to meet shared long-term climate benefits, clean air and energy access targets. The short-term details are based on the IEA’s sustainable recovery strategy, which aims to promote economies and employment through developing a cleaner and more reliable energy infrastructure [ 15 ]. In addition, sustainable development includes utilizing renewable-energy applications, smart-grid technologies, energy security, and energy pricing, and having a sound energy policy [ 29 ].

The demand-side response can help meet the flexibility requirements in electricity systems by moving demand over time. As a result, the integration of renewable technologies for helping facilitate the peak demand is reduced, system stability is maintained, and total costs and CO 2 emissions are reduced. The demand-side response is currently used mostly in Europe and North America, where it is primarily aimed at huge commercial and industrial electricity customers [ 15 ].

International standards are an essential component of high-quality infrastructure. Establishing legislative convergence, increasing competition and supporting innovation will allow participants to take part in a global world PV market [ 30 ]. Numerous additional countries might benefit from more actively engaging in developing global solar PV standards. The leading countries in solar PV manufacturing and deployment have embraced global standards for PV systems and highly contributed to clean-energy development. Additional assistance and capacity-building to enhance quality infrastructure in developing economies might also help support wider implementation and compliance with international solar PV standards. Thus, support can bring legal requirements and frameworks into consistency and give additional impetus for the trade of secure and high-quality solar PV products [ 19 ].

Continuous trade-led dissemination of solar PV and other renewable technologies will strengthen the national infrastructure. For instance, off-grid solar energy alternatives, such as stand-alone systems and mini-grids, could be easily deployed to assist healthcare facilities in improving their degree of services and powering portable testing sites and vaccination coolers. In addition to helping in the immediate medical crisis, trade-led solar PV adoption could aid in the improving economy from the COVID-19 outbreak, not least by providing jobs in the renewable-energy sector, which are estimated to reach >40 million by 2050 [ 19 ].

The framework for energy sustainability development, by the application of solar energy, is one way to achieve that goal. With the large availability of solar energy resources for PV and CSP energy applications, we can move towards energy sustainability. Fig. 3 illustrates plans for solar energy sustainability.

Framework for solar energy applications in energy sustainability.

The environmental consideration of such applications, including an aspect of the environmental conditions, operating conditions, etc., have been assessed. It is clean, friendly to the environment and also energy-saving. Moreover, this technology has no removable parts, low maintenance procedures and longevity.

Economic and social development are considered by offering job opportunities to the community and providing cheaper energy options. It can also improve people’s income; in turn, living standards will be enhanced. Therefore, energy is paramount, considered to be the most vital element of human life, society’s progress and economic development.

As efforts are made to increase the energy transition towards sustainable energy systems, it is anticipated that the next decade will see a continued booming of solar energy and all clean-energy technology. Scholars worldwide consider research and innovation to be substantial drivers to enhance the potency of such solar application technology.

2.1 Employment from renewable energy

The employment market has also boomed with the deployment of renewable-energy technology. Renewable-energy technology applications have created >12 million jobs worldwide. The solar PV application came as the pioneer, which created >3 million jobs. At the same time, while the solar thermal applications (solar heating and cooling) created >819 000 jobs, the CSP attained >31 000 jobs [ 20 ].

According to the reports, although top markets such as the USA, the EU and China had the highest investment in renewables jobs, other Asian countries have emerged as players in the solar PV panel manufacturers’ industry [ 31 ].

Solar energy employment has offered more employment than other renewable sources. For example, in the developing countries, there was a growth in employment chances in solar applications that powered ‘micro-enterprises’. Hence, it has been significant in eliminating poverty, which is considered the key goal of sustainable energy development. Therefore, solar energy plays a critical part in fulfilling the sustainability targets for a better plant and environment [ 31 , 32 ]. Fig. 4 illustrates distributions of world renewable-energy employment.

World renewable-energy employment [ 20 ].

The world distribution of PV jobs is disseminated across the continents as follows. There was 70% employment in PV applications available in Asia, while 10% is available in North America, 10% available in South America and 10% availability in Europe. Table 1 details the top 10 countries that have relevant jobs in Asia, North America, South America and Europe.

List of the top 10 countries that created jobs in solar PV applications [ 19 , 33 ]

Solar energy investments can meet energy targets and environmental protection by reducing carbon emissions while having no detrimental influence on the country’s development [ 32 , 34 ]. In countries located in the ‘Sunbelt’, there is huge potential for solar energy, where there is a year-round abundance of solar global horizontal irradiation. Consequently, these countries, including the Middle East, Australia, North Africa, China, the USA and Southern Africa, to name a few, have a lot of potential for solar energy technology. The average yearly solar intensity is >2800 kWh/m 2 and the average daily solar intensity is >7.5 kWh/m 2 . Fig. 5 illustrates the optimum areas for global solar irradiation.

World global solar irradiation map [ 35 ].

The distribution of solar radiation and its intensity are two important factors that influence the efficiency of solar PV technology and these two parameters vary among different countries. Therefore, it is essential to realize that some solar energy is wasted since it is not utilized. On the other hand, solar radiation is abundant in several countries, especially in developing ones, which makes it invaluable [ 36 , 37 ].

Worldwide, the PV industry has benefited recently from globalization, which has allowed huge improvements in economies of scale, while vertical integration has created strong value chains: as manufacturers source materials from an increasing number of suppliers, prices have dropped while quality has been maintained. Furthermore, the worldwide incorporated PV solar device market is growing fast, creating opportunities enabling solar energy firms to benefit from significant government help with underwriting, subsides, beneficial trading licences and training of a competent workforce, while the increased rivalry has reinforced the motivation to continue investing in research and development, both public and private [ 19 , 33 ].

The global outbreak of COVID-19 has impacted ‘cross-border supply chains’ and those investors working in the renewable-energy sector. As a result, more diversity of solar PV supply-chain processes may be required in the future to enhance long-term flexibility versus exogenous shocks [ 19 , 33 ].

It is vital to establish a well-functioning quality infrastructure to expand the distribution of solar PV technologies beyond borders and make it easier for new enterprises to enter solar PV value chains. In addition, a strong quality infrastructure system is a significant instrument for assisting local firms in meeting the demands of trade markets. Furthermore, high-quality infrastructure can help reduce associated risks with the worldwide PV project value chain, such as underperforming, inefficient and failing goods, limiting the development, improvement and export of these technologies. Governments worldwide are, at various levels, creating quality infrastructure, including the usage of metrology i.e. the science of measurement and its application, regulations, testing procedures, accreditation, certification and market monitoring [ 33 , 38 ].

The perspective is based on a continuous process of technological advancement and learning. Its speed is determined by its deployment, which varies depending on the scenario [ 39 , 40 ]. The expense trends support policy preferences for low-carbon energy sources, particularly in increased energy-alteration scenarios. Emerging technologies are introduced and implemented as quickly as they ever have been before in energy history [ 15 , 33 ].

The CSP stations have been in use since the early 1980s and are currently found all over the world. The CSP power stations in the USA currently produce >800 MW of electricity yearly, which is sufficient to power ~500 000 houses. New CSP heat-transfer fluids being developed can function at ~1288 o C, which is greater than existing fluids, to improve the efficiency of CSP systems and, as a result, to lower the cost of energy generated using this technology. Thus, as a result, CSP is considered to have a bright future, with the ability to offer large-scale renewable energy that can supplement and soon replace traditional electricity-production technologies [ 41 ]. The DESERTEC project has drawn out the possibility of CSP in the Sahara Desert regions. When completed, this investment project will have the world’s biggest energy-generation capacity through the CSP plant, which aims to transport energy from North Africa to Europe [ 42 , 43 ].

The costs of manufacturing materials for PV devices have recently decreased, which is predicted to compensate for the requirements and increase the globe’s electricity demand [ 44 ]. Solar energy is a renewable, clean and environmentally friendly source of energy. Therefore, solar PV application techniques should be widely utilized. Although PV technology has always been under development for a variety of purposes, the fact that PV solar cells convert the radiant energy from the Sun directly into electrical power means it can be applied in space and in terrestrial applications [ 38 , 45 ].

In one way or another, the whole renewable-energy sector has a benefit over other energy industries. A long-term energy development plan needs an energy source that is inexhaustible, virtually accessible and simple to gather. The Sun rises over the horizon every day around the globe and leaves behind ~108–1018 kWh of energy; consequently, it is more than humanity will ever require to fulfil its desire for electricity [ 46 ].

The technology that converts solar radiation into electricity is well known and utilizes PV cells, which are already in use worldwide. In addition, various solar PV technologies are available today, including hybrid solar cells, inorganic solar cells and organic solar cells. So far, solar PV devices made from silicon have led the solar market; however, these PVs have certain drawbacks, such as expenditure of material, time-consuming production, etc. It is important to mention here the operational challenges of solar energy in that it does not work at night, has less output in cloudy weather and does not work in sandstorm conditions. PV battery storage is widely used to reduce the challenges to gain high reliability. Therefore, attempts have been made to find alternative materials to address these constraints. Currently, this domination is challenged by the evolution of the emerging generation of solar PV devices based on perovskite, organic and organic/inorganic hybrid materials.

This paper highlights the significance of sustainable energy development. Solar energy would help steady energy prices and give numerous social, environmental and economic benefits. This has been indicated by solar energy’s contribution to achieving sustainable development through meeting energy demands, creating jobs and protecting the environment. Hence, a paramount critical component of long-term sustainability should be investigated. Based on the current condition of fossil-fuel resources, which are deemed to be depleting energy sources, finding an innovative technique to deploy clean-energy technology is both essential and expected. Notwithstanding, solar energy has yet to reach maturity in development, especially CSP technology. Also, with growing developments in PV systems, there has been a huge rise in demand for PV technology applications all over the globe. Further work needs to be undertaken to develop energy sustainably and consider other clean energy resources. Moreover, a comprehensive experimental and validation process for such applications is required to develop cleaner energy sources to decarbonize our planet.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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• Published: 17 October 2023

The momentum of the solar energy transition

• Femke J. M. M. Nijsse   ORCID: orcid.org/0000-0002-6674-5350 1 ,
• Jean-Francois Mercure   ORCID: orcid.org/0000-0003-2620-9200 1 , 2 , 3 ,
• Nadia Ameli   ORCID: orcid.org/0000-0002-6728-9190 4 ,
• Francesca Larosa   ORCID: orcid.org/0000-0002-4350-8790 4 , 5 ,
• Sumit Kothari   ORCID: orcid.org/0000-0002-4560-1059 4 ,
• Jamie Rickman 4 ,
• Pim Vercoulen   ORCID: orcid.org/0000-0002-2468-5513 1 , 6 &
• Hector Pollitt 2 , 3  

Nature Communications volume  14 , Article number:  6542 ( 2023 ) Cite this article

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• Energy modelling
• Solar energy

Decarbonisation plans across the globe require zero-carbon energy sources to be widely deployed by 2050 or 2060. Solar energy is the most widely available energy resource on Earth, and its economic attractiveness is improving fast in a cycle of increasing investments. Here we use data-driven conditional technology and economic forecasting modelling to establish which zero carbon power sources could become dominant worldwide. We find that, due to technological trajectories set in motion by past policy, a global irreversible solar tipping point may have passed where solar energy gradually comes to dominate global electricity markets, without any further climate policies. Uncertainties arise, however, over grid stability in a renewables-dominated power system, the availability of sufficient finance in underdeveloped economies, the capacity of supply chains and political resistance from regions that lose employment. Policies resolving these barriers may be more effective than price instruments to accelerate the transition to clean energy.

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Introduction.

A rapid transformation of the energy system is necessary to keep warming well below 2 °C, as set out in the Paris Agreement and reinforced in the Glasgow Pact. Many countries have committed to achieving net-zero targets by 2050 (incl. EU, UK, Japan, Korea), 2060 (China) or 2070 (India). Net-zero targets imply mass-scale deployment of zero-carbon energy technologies such as solar and wind power, likely in combination with negative emission technologies 1 . However, the potential for negative emissions to compensate positive emissions remains relatively limited 2 , 3 .

Renewables have historically been considered expensive, their deployment requiring high subsidies or carbon taxes 4 , 5 . However, following a fruitful history of innovation and past climate policy, renewables now increasingly compete with fossil fuels 6 , 7 . Whether renewables become the new normal increasingly hinges upon industry and trade development rather than a pure normative necessity to meet carbon budgets 7 , 8 , 9 . Policy-makers urgently need to know not only whether a renewables future is possible, but whether it is materialising.

Between 2010 and 2020, the cost of solar PV fell by 15% each year, representing a technological learning rate of around 20% per doubling of installed capacity 8 . At the same time, the installed capacity has risen by 25% per year, causing and partly caused by these cost reductions. Meanwhile, onshore wind capacity grew by 12% a year, with a learning rate of 10% per doubling of capacity 8 , 9 . If these rates of rapid co-evolution are maintained, solar PV and wind power appear ready to irreversibly become the dominant electricity technologies within 1-2 decades, as their costs and rate of growth far undercut all alternatives. Were that to be the case, a renewables tipping point in the power sector could be imminent or even already have been passed, and the policy and finance spheres should prepare for a rapid disruptive transition. Despite this evidence, the energy modelling community has not yet identified this possibility with any degree of consensus 8 , suggesting instead that fossil fuel-dominated electricity systems would likely continue as a result from inadequate carbon pricing.

The problem of high cost for renewables has changed into a problem of balancing electricity grids, in which large amounts of intermittent wind and solar generation pose challenges. Batteries play an important role in mitigating that issue and show a similarly high learning rate 10 . This implies that electricity storage costs and diffusion could follow a comparable and coupled trajectory to PV in the 2020s.

Whether solar and wind can dominate electricity grids depends on the ability of the technology to overcome a series of barriers. This includes how to deal with the seasonal variation for which batteries are ill-suited 11 . The cost of managing large amounts of intermittency could offset further cost reductions in solar panels and wind turbines, impeding their rapid diffusion 12 . The unequal availability of finance to support solar and wind investments in various countries 13 may be an issue, too. Supply chains may be poorly prepared for such a rapid technological roll out 14 . Finally, political resistance in areas of declining fossil fuel use or trade could curb the willingness of governments to embrace a solar revolution 15 .

Here, we use a global, data-driven energy-technology-economy simulation model (E3ME-FTT) to conditionally forecast the deployment of energy technologies up to 2060, under current policy regimes. We focus on identifying the existence of a tipping point for solar and wind, assuming that no further policy is adopted to usher in a solar and wind-dominated electricity system. We then explore in detail the various barriers that could impede this renewables revolution, and identify what non-traditional policies could be used to bridge those gaps.

Historical projections of energy generation have consistently underestimated uptake rates of solar energy 16 , 17 . For example, only a year after the publication of the 2020 World Energy Outlook (WEO), the IEA’s “Stated policies scenario” has been revised strongly in favour of solar energy. Nevertheless, the total share of solar in power production only reaches 20% by 2050 in that baseline scenario despite historically low prices 18 . Systematic underestimation of low-carbon technology deployment in energy models could stem from systematic lack of suitable or realistic representation of induced innovation and diffusion processes 19 , 20 , 21 .

Solar energy started its journey in niche markets, like most innovations, supplying electricity to applications where little alternatives existed in space and remote locations 22 . Since then, cumulative investments and sales, driven by past policy, have made its cost come down by almost three orders of magnitude. The introduction of feed-in tariffs in mainly Germany induced a volume of investment and related cost reductions, that brought the technology to mainstream markets following Chinese involvement in supply chains 7 .

Cost reductions and rapid deployment work hand in hand, something observed for many technologies 7 . Deployments typically follow Rogers’ S-curve diffusion 23 , with a bi-directional interaction with cost reductions from Wright’s law 24 . For solar (and wind), rapid deployments, supported by past policies, have pushed down technology costs. This promotes further diffusion in a virtuous cycle 7 . Such nonlinearity in the diffusion process raises the possibility of an irreversible tipping point 25 .

There are many reasons why solar has experienced such high learning rates. Its simplicity, modularity and mass-scale replicability allow for significant learning opportunities, related to those seen across the electronics industry 26 , 27 , 28 . Indeed, numerous spillovers have originated from the computer industry 22 . Innovation and improvements to solar PV are ongoing. For instance, the commercialisation of (hybrid) perovskite cells holds promises for higher efficiencies and lower unit prices 29 , 30 . Due to decreasing technology risks and financial learning, finance is partly cheaper to procure 31 . Progress in recycling helps material supply security and may decrease life-cycle costs 32 . Meanwhile, the chemical diversity of batteries, a storage technology highly supportive of solar PV, makes it likely that further cost declines can be achieved 33 .

The historical failure of the modelling community to anticipate the rapid progress of solar power could stem from an over-reliance outdated data, the lack of use of learning curves, and the imposition of maximum deployment levels and floor costs 16 , 34 . As the primary innovation in this paper, forecasting technology evolution and induced innovation can more effectively be achieved based on evolutionary simulations, using the most recent data available, that focus on the two-way positive feedback between induced innovation and diffusion 24 , 35 .

This work supplements recent research by Way et al. 16 . Way et al. developed a probabilistic empirically validated global model of energy technology costs. The research showed that a scenario of high renewables uptake leads to a significantly lower-cost energy system, and the authors argued that energy models should be updated to reflect the high probability of low-cost renewables. This paper differs in two key ways: 1) we do not impose a scenario, but rather allow investor decisions to dictate the deployment of technologies. 2) we use a globally disaggregated model and look at region-specific alternative sources of electricity.

Towards a new baseline scenario

Following the recent progress of renewables, fossil fuel-dominated projection baselines are not realistic anymore. Here, we focus on the co-evolving dynamics of diffusion and innovation to project the mid to long-term diffusion trajectory of 24 power technologies. We use the historical data-driven E3ME-FTT integrated energy-economy model, in which a system dynamics simulation method, combined with choice modelling (see Methods), tracks the positive feedbacks that emerge between cost reductions and diffusion, something not usually represented in models that have fixed yearly learning 5 . We use IEA data for historical generation, CAPEX and OPEX, BNEF for capacity factors, construction and lifetimes until 2020, IRENA for historical renewables capacity data between 2019 and 2021.

Technological trajectories typically have inertia in their diffusion that depend on their lifecycle turnover, with half-lives ranging between 10 and 15 years for short-lived units (cars), 25–40 years for fossil fuel plants, and 50–100 years for long-lived infrastructure, such as nuclear plants and hydro dams 36 . These long lifetimes prevent technological trajectories from changing direction abruptly. This autocorrelation time in the direction of evolution (or degree of inertia) implies that energy system technological forecasting constrained by observed diffusion and cost trajectories, as done here, can be reliable within at least 15-20 years, subject to an increasing error that cumulates over the simulation time span.

Figure  1 shows the global share of electricity production of 11 key technologies (Supplementary Figure  1 for a regional breakdown). The current mix is highly varied. By mid-century, according to E3ME-FTT, solar PV will have come to dominate the mix, even without any additional policies supporting renewables. This is due to solar costs declining far below the costs of all alternatives, while its parent industrial supply capacity increases rapidly. Its scale expands, because of its current rapid and exponential diffusion trajectory and comparatively high learning rate. Even the market shares of onshore and offshore wind power in the global electricity mix start declining around 2030, outpaced by solar. This is due to a lower learning rate of wind compared to solar and a growing cost gap in the model. However, onshore continues growing in absolute terms until 2040, and offshore to the end of the simulation. Concentrated solar power grows over the entire period, but without targeted policy its overall share in the power mix remains small, despite its advantage as a dispatchable source of electricity.

In 2020, fossil fuels produce 62% of electricity. This percentage reduces to 21% in 2050, with solar responsible for 56% of production.

The trend towards renewables dominance (Fig.  2a ) and notably solar PV (Fig.  2b ) appears imminent in China, and lags in Africa and Russia. Africa lags despite a very high technical potential and low seasonality. The slow uptake can mostly be attributed to nonpecuniary aspects (grid flexibility, trust in new technologies), which requires prices to fall further below alternatives before there is significant uptake. This occurs after uptake by other countries drives down prices further.

a total renewables (hydro + wind + solar + biomass) and ( b ) solar PV. Initially, renewables are dominated by hydropower and to a lesser extent wind. This is soon overtaken by solar, depending on regional factors.

The levelised cost of electricity (LCOE ssc , which includes system storage costs, see Methods) is shown in Fig.  3 . We tentatively assign additional system costs for storage to be borne by renewable energy producers. Even though storage needs increase substantially over time, LCOE for solar energy decreases overall. This is because the learning rate for short-term storage is very high, and the learning rate for long-duration storage (we assume hydrogen is used for seasonal storage) is expected to be relatively high too 8 . Of the major countries shown, solar PV is initially more expensive than coal only in Japan, where cost-parity is reached around 2025.

a EU-27 ( b ) United States ( c ) India ( d ) China ( e ) Japan and ( f ) Brazil. Shaded areas are the 10–90% confidence interval. Solar PV + system storage is already among the cheapest forms of electricity. In some regions, wind and solar remain competitive, whereas solar becomes much cheaper in others. Without carbon taxation, coal is typically cheaper than gas.

In 2020, wind energy has the lowest LCOE in a majority the 70 regions defined in the E3ME-FTT models (Fig.  4 ). Where this is not the case, solar PV, nuclear or coal dominate. By 2030, this has flipped, in favour in solar power across most of the world (see Supplementary Figs.  2 and 3 for worst/best case maps). We assume a uniform declining cost per kW of PV panels worldwide, with differing solar irradiation for each region. This assumption is based on empirical findings 37 . Due to this international spillover effect, most regions of the world are likely going to gain access to low-cost solar energy. As such, a region may reach cost parity between solar and the cheapest alternative through the influence of other countries on the scale of production and costs, even if cumulative investments in that region are modest. This implies that developing countries could become realistic markets for solar energy even when the capacity of their governments to implement climate policies remains limited.

Each map shows the 70 E3ME regions: in 2020 ( a ), 2023 ( b ), 2027 ( c ) and 2030 ( d ). The biggest shift occurs between 2020 and 2027, which sees a range of technologies give way to solar PV as the cheapest source of electricity.

Figure  5 shows the robustness of the result to a set of model assumptions (see Methods). The two most important sources of uncertainty are potential delays in making necessary grid adjustments and the learning rate for wind power. If installing solar power plants takes twice as long due to delays with grid expansions, the median share of solar in 2050 drops by 16 percentage points. Notably, with solar prices far below alternatives, higher learning rates have a small effect on diffusion. Overall, in 72% of the simulations done for robustness testing, solar makes up more than 50% of power generation in 2050. This suggests that solar dominance is not only possible but also likely.

a The overall histogram of the 2050 shares of solar PV. b The shares solar PV depending on who pays for storage costs (variable renewable energy (VRE) sources, or the grid operator). Box plot elements: Centre line: median, box limit: upper and lower quartiles, whiskers: 1.5x interquartile range, points: outliers c , Shares of solar PV depending on the learning rate of onshore and offshore wind energy, d , depending on the learning rate of solar PV and e , depending on the lead time for solar projects.

These projections and sensitivities give us some confidence to suggest that realistic energy model baselines should, from now on, include substantially larger shares of solar energy than what is commonly assumed, as they make coal and gas-dominated baseline scenarios largely unrealistic. The main scenario framework assessed in the IPCC reports, the socialeconomic pathways (SSPs), include scenarios with increasing reliance on coal to the energy mix 38 . This work notably indicates these scenarios are highly improbable.

The above projections appear robust with respect to cost and technical factors included in the model. However, systemic problems not modelled could, nevertheless, develop into barriers hindering achieving climate targets. This suggests that further climate policy action should focus on addressing these barriers.

Overcoming barriers

We highlight four barriers that go beyond considerations of levelized costs and a) may significantly slow down the solar tipping point if unaddressed b) are global and c) are not fully implemented into integrated assessment models. The four identified encompass the technological, policy, market and economic, regulatory, political and social barriers identified by the literature 39 as the most relevant for solar PV deployment in the next three decades.

As a first barrier, we consider grid resilience. In many published energy scenarios with higher shares of solar and wind power, “dark doldrums”, periods of simultaneously low wind speeds and solar irradiation, form the predominant vulnerability 40 . From geophysical constraints, it is possible to compute an optimal mix of wind and solar power, which maximises the match between supply and demand. The typical optimal share of solar when 12 h of battery storage is available lies between 10–70%, depending on geography. Where less storage is available, the optimal mix shifts towards more wind power 11 . When either of the two main technologies is (near)-absent, the grid becomes more vulnerable to weather fluctuations. As such, solar-dominated grids may not be desirable. Importantly, no mechanism guarantees that optimal grids are achieved if left to market forces, especially in contexts of diverging technology costs, and solar dominance could become self-limiting. While E3ME-FTT models grid constraints of a typical year, weather extremes are not considered.

The self-limiting effect of solar PV diffusion due to intermittency can be overcome with a policy mix supporting wind power and other zero-carbon energy sources, as well as improved storage, grid connections and demand-response. Notably, new power market rules can be designed to incentivise investment in generators that complement solar production on a daily to seasonal scale, according to the savings in storage that they generate. Specifically, our model suggests that the allocation of storage costs to the grid and charged directly to consumers incentivises more renewables diffusion than requiring renewables to carry the full burden of storage needs (see Fig.  5 ), leading to lower overall system costs 41 .

Secondly, the availability of finance may act as a barrier. Solar growth trajectories will inevitably depend on the availability of finance. Low-carbon finance is presently highly concentrated in high-income countries 42 . Even international North-South flows largely favour middle-income countries, leaving lower income countries – particularly those in Africa – deficient in solar finance despite the enormous investment potential 42 .

This unequal distribution of finance reflects different investment risk considerations across countries. Differences in local financial environments, such as macroeconomic conditions, business confidence, policy uncertainty and regulatory frameworks impact risk perceptions and the willingness to invest by domestic and international actors 13 . Equity investors and financial lenders apply high-risk premiums in perceived risky regional contexts, thus increasing the cost of capital for renewable projects 13 , 43 .

Developing countries are particularly financially and fiscally constrained. Domestically they are characterised by under-developed capital markets and lack capital stock 44 ; whereas international finance is restricted due to high sovereign risks and local currency risks on account of volatile economic fundamentals (as projects are funded with foreign currency while returns are generated in local currencies 45 , 46 ). This leads to a chronic lack of available finance to support investments in solar energy.

Energy sector deficiencies further exacerbate the negative investment outlook for solar projects. Weak contract enforcement, changing energy regulations, and underdeveloped electricity markets affect project returns and investment viability. Developing countries may also face high import costs due to shortages in foreign currency reserves needed to support an expanding solar sector.

Consequently, a key challenge for global solar deployment lies in the mismatch between high investment needs (see Fig.  6 for modelled investment needs) and finance flows mobilised in developing countries 44 . Latest estimates suggest that climate financial flows would need to increase by a factor 4 to 8 in most vulnerable countries (IPCC 2022) 47 . Strategies to address this finance gap should include mechanisms to absorb currency and investment risk as a bridge to unlock international capital flows while creating domestic financial capacity over time.

a shows power sector investments as a percentage of GDP. The strong peak around 2030 for China and India is explained by a saturation in addition of additional solar capacity, in combination with a growing GDP and declining solar costs. b shows power sector investment with respect to 2019 values. Investment is forecast to see a fast growth worldwide relative to historical trends. Various regions in the Global South, in particular India and Africa, will see an even steeper rise in investment in generating capacity by mid-century, due to projected rapid economic growth.

As a third barrier, we discuss supply chains. A solar-dominated future is likely to be metal and mineral-intensive 48 . Future demand for “critical minerals” will increase on two fronts: electrification and batteries require large-scale raw materials – such as lithium and copper; niche materials, including tellurium, are instrumental for solar panels 49 . As countries accelerate their decarbonisation efforts, renewable technologies are projected to make up 40% of total mineral demand for copper and rare earth elements, between 60 and 70% for nickel and cobalt, and almost 90% for lithium by 2040 14 .

The notion of criticality comes in three forms: physical, economic, and geopolitical. Firstly, there are risk associated with low reserves. Secondly, minerals supply typically reacts slowly to short-term changes in demand in, due to the long times required to establish mineral supply chains. This could lead to price rallies. The construction of new mining facilities (from exploration to mine operations) requires on average 16.5 years 14 and may be stalled due to concerns about socio-environmental impacts 50 .

The geopolitical supply reliability of critical minerals is also weak, since mineral production displays higher geographical concentration, compared to fossil fuels production. China and The Democratic Republic of Congo, for example, own 60% and 70% of current global production of rare earth minerals and cobalt respectively 51 . Domestic shocks, including growing climate risks and political instability, could hamper the extraction and production and generate price shocks that along the value chain, impacting solar technology costs. Electricity networks could suffer similar impacts for nickel and aluminium.

Risk associated with low reserves can be mitigated with (research into) substitutions 52 . Recycling and circular economy processes can further reduce extraction rates, but re-used materials are unlikely to meet future demand as it outgrows existing stocks 53 .

Lastly, resistance from declining industries may impact the transition. The pace of the transition depends not only on (economic) decisions by entrepreneurs, but also on how desirable policy makers consider it. Solar energy aligns with many policy objectives (clean air, poverty alleviation, energy security 54 ). It also has disadvantages for some of the players involved, as it leads to rapid economic and industrial change.

Solar and wind power have a low energy density compared to alternatives. In most countries, they can provide enough energy to meet demand. However, land for renewables may be scarce close to population centres in some parts of the world 55 , 56 . Political tension on the use of land and water (for floating photovoltaics 57 ) may increase as solar shares rise.

A rapid solar transition may also put at risk the livelihood of up to 13 million people worldwide working in fossil fuel industries and dependent industries. These people are frequently concentrated in communities close to mines extraction and industrial sites, where the closure of these activities can have severe repercussion on the well-being of communities decades on 58 . Policy makers could have substantial incentives to slow down the transition to limit these direct impacts. Similarly, many countries currently provide fossil fuel subsidies to increase the purchasing power of low-income households, difficult to phase out and which reinforce opposition to change. New coalitions of actors who benefit from the transition (home and landowners, people with jobs in clean energy), may counterbalance some of the resistance from incumbents 15 , but do not resolve equity issues. Regional economic and industrial development policy can resolve inequity, and can mitigate risks posed by resistance from declining industries 59 .

Without any further energy policy changes, solar energy appears to follow a robust trajectory to become the future dominant power source before mid-century. Due to the reinforcing co-evolution of technology costs and deployment, our analysis establishes quantitative empirical evidence, from current and historical data trends, that a solar energy tipping point is likely to have passed. Once the combined cost of solar and storage crosses cost parity with all alternative technologies in several key markets, its widespread deployment and further costs declines globally could become irreversible. This echoes the results from Way et al. 16 , who showed that such a configuration would be cheaper than alternatives 60 .

A tipping point towards solar dominance however does not solve climate change mitigation or achieve climate targets, as it does not ensure a zero-carbon energy system. Solar-dominated electricity systems could become locked into configurations that are neither resilient nor sustainable with a reliance on fossil fuel for dispatchable power. Issues that could hinder achieving zero-carbon energy systems include grid stability issues, the availability of financial capital and critical minerals, and the willingness of decision-makers to get onboard a rapid transition that could generate substantial distributional issues in their respective regions. The energy crisis resulting from the war in Ukraine suggests that the accelerated move away from fossil fuels is needed even more urgently.

We conclude that achieving zero-carbon power systems likely requires policies of a different kind than have traditionally been discussed by the energy modelling community. The carbon price required to achieve cost break-even between renewables and fossil fuels may soon be zero. Instead, it is policies that address the above barriers—grid resilience, access to finance, management of material supply chains and political opposition—that may enable success in reaching net-zero energy emissions.

E3ME-FTT-GENIE 61 is a model based on path-dependent simulation parameterised by historical data and technology diffusion trajectories. Integrated assessment models are typically based on utility or whole-system cost optimisation. Those models have played an important role in the energy debate by characterising what an optimal composition of the energy system ought to look like. They are less suitable for studying trends in energy system dynamics since, being driven by a centralised social planner construct, they neglect historical relationships, economic causality structures and decision-making processes 35 , 62 . In contrast, path-dependent energy system and economy simulations model system evolution on the basis of known causality structures and decision-making parameterised by timeseries and other data, however they do not identify optimal system configurations or policy. Decision-making by investors does not always line up with an optimal system, as investors use shorter time-scales to evaluate decisions compared to a putative ‘social planner’.

In this paper, we use the energy-economy-environment (E3) simulation model E3ME-FTT-GENIE. It is grounded in empirically derived relationships between economic and technology variables, under the highest sectoral and regional disaggregation available for a global model (43 sectors and 70 regions) and a large number of energy technologies (88 technologies). Evolutionary dynamics form the core of technology evolution where induced innovation plays an important role; those sectors are represented by the various FTT submodels, which portray the typical S-shaped dynamics of technology uptake 63 . The model includes energy markets for nonrenewable and renewable energy. The GENIE climate and carbon cycle model is soft-coupled – emissions from E3ME-FTT drive the GENIE, but the GENIE does not affect the global economy. A complete set of equations for the E3ME-FTT model is given in Mercure et al. 61 , with updates for the Power model found in Simsek et al. 41 .

The Future Technology Transformation (FTT) family of models provide an in-depth representation of four climate-relevant sectors in which technological change plays an important role: power, transport 64 , heating 65 and steel 66 . These are the four energy end-use sectors with the highest greenhouse gas emissions. The models are based on evolutionary dynamics, simulating the S-curve of technology uptake characteristic of innovation 23 . Its core is the replicator dynamics equation (known as the Lotka-Volterra equation), prominent in ecosystem population dynamics modelling 67 .

The direction of diffusion of a technology in FTT is primarily driven by comparing the levelised cost of technology options in chains of binary discrete choice models, where the frequency of choice options availability is weighted by the share of those options in the technology mix. The levelised costs being compared are designed as to be a suitable depiction of decision making in each specific sector. A factor is included in each levelised cost, that captures non-pecuniary aspects otherwise not be captured with available data on costs alone. These are calibrated to match observed diffusion trajectories for each technology. For instance, technologies that are more socially attractive than their market costs suggest will have a negative factor included in the LCOE.

Power represents the diffusion of 24 technologies in the power sector. It includes nuclear, a set of bio-energy technologies, seven technologies based on the combustion of fossil fuels (including CCS options). Onshore and offshore wind, solar PV and CSP, hydro power, tidal, geothermal and wave power are also represented. FTT:Heat depicts the competition between various combustion technologies (oil, coal, wood and gas- burning) in households, as well as electrified heating options (resistive electric heating and heat pump technologies) and finally district and solar heating. FTT:Transport models the competition between petrol, diesel, LPG, EVs and hybrid passenger vehicles, as well as motor vehicles. For each base technology, there is a further disaggregation based on the luxury of the vehicle. Finally, FTT:Steel models 25 different routes of steel production: on the basis of coal, gas, hydrogen and electricity.

FTT Power follows Ueckerdt et al. 68 in its detailed representation of variable renewables in grid stability. Technologies are classified along six load bands, and production is allocated to available technologies based on intermittency and flexibility constraints. This takes into account the hourly demand over time in a set of key regions, and hourly supply potential per technology. For each mix of variable renewables, the optimal curtailment and storage needs are estimated using the parametrizations from Ueckerdt et al. 68 . Compared to earlier treatment in FTT, this implies much improved and less conservative assumptions over limits to renewables in power grids due to intermittency 41 .

The baseline scenario (the only scenario in this paper) includes the EU Emission Trading System explicitly, as well as the ongoing nuclear phase-out in Germany and Belgium. Other policies are included implicitly by adding “gamma values” to the LCOE values used for decision-making by investors. These gamma values are calibrated to produce short-term projection of power capacity shares in each country that is consistent with the recent historical trend, by minimising the difference in rate of growth or decline at the changeover point between history and simulation. As a conservative assumption, we do not include a premature retirement of power plants when their marginal costs rise above the LCOE of newly installed power plants. We also do not include the possibility to extend the lifetimes of power plants.

The CAPEX and OPEX costs are derived from the IEA’s Projected Costs of Generating Electricity 2020 , and medians are used to fill in missing data. For solar, we use utility-scale solar prices. Residential solar power is more expensive, but the attractiveness for consumers is heightened by the fact they avoid various taxes on electricity. Standard deviations of these costs are also derived from this dataset; this means that volatility over time is not captured in our uncertainty.

This paper includes a further set of updates to FTT:Power that collectively favour the diffusion of solar PV into the electricity mix. Based on historical data from BNEF (see Supplementary Figure  4 ), we introduce learning in operational costs, rather than only in CAPEX, which mostly benefits offshore wind and solar PV. Learning rates are updated for key technologies, following Way et al. 8 . Both solar power and wind energy see a higher learning rate than previous model versions. Based on recent estimates of panel lifetime, we assume that a solar panel lasts 30 years on average.

Using BNEF data up to 2020, through a whole-model data upgrade, we update realised capacity factors for onshore, offshore, and solar technologies to the most recent values. The timescale for developing offshore wind projects is found to be longer than onshore wind, which hinders rapid growth.

The technical potential for onshore wind is updated using 69 , which has an improved resolution, threshold wind speed and turbine technical specifications compared to 70 . For solar power (solar PV and CSP), we updated the technical potential as the sum of 71 (utility-scale solar) and 72 (rooftop solar). We did not include a technical potential 57 for application of solar power on water (“floatovoltaics”), as this technology is still in early stages of development.

Regions with offshore potential, but no installed capacity, are attributed a small offshore wind capacity, equal to 1/100 the capacity of onshore wind installed in the region or country. Similar seeding is performed for CSP, which equals 1/100 the capacity of solar in the country. For countries without any onshore capacity, a small capacity, equal to 0.1% of historical generation, is added. This is because technology with zero deployment will never be selected. Historical installed capacity of renewables is inserted using 9 .

We innovate by introducing learning in storage technologies, which were, in the original model, fixed at the estimated 2030 price levels. For short-term storage we take the average of the learning rate for lithium-ion batteries and vanadium flow batteries. The latter are less common currently, but provide more flexibility and have a lower environmental impact 73 . The averaged learning exponent is 0.255 and long-term storage (assumed to be supplied by hydrogen) a more modest learning of 0.194 based on 8 . System storage costs are divided over the variable renewables. Both short-term storage costs and long-term storage costs increase with a poorer ratio between sun and wind. CSP only contributes to long-term storage costs, as it contains short-term storage internally. This is a conservative assumption for variable renewable energy diffusion, as policy may attribute storage costs to all grid participants or directly to customers.

The uncertainty analysis of Fig.  3 , Fig.  5 and Supplementary Figure  5 is performed with a Monte Carlo sampling of a set of input parameters. Input parameters were selected that had the largest expected impact on the diffusion of power generation technologies. In half of cases, costs of power storage were attributed equally among participants in the power market, whereas the costs of storage were allocated to renewables in the other half (the default). Inequality around access to capital between countries was modelled via the discount rate: the costs of finance (WACC/discount rate) was varied between 0.075 and 0.100 for countries in the OECD, and varied between 0.100 and 0.125 for all other countries. The learning rates for solar and wind were varied per the distribution given in Way et al. 8 . The importance of nonpecuniary aspects (gamma values), captured using calibration, was multiplied by a value drawn from the normal distribution N(1, 0.2). Similarly, fuel costs for gas and coal were varied by a factor drawn from the same normal distribution. Possible delays in grid expansion (f.i. to resolve grid congestion) are expressed as increasing the lead time of solar PV development with a Poisson distribution. The lifetime of solar panels was varied uniformly between 25 and 35 years.

The E3ME model is the macro-econometric component of the modelling framework. It is demand-led and features 70 regions and countries, covering the world. Each EU member and the UK has a representation of 70 sectors; other regions are represented to 43 economic sectors. The sectors are linked with input-output tables, and bilateral trade equations link the various regions and countries. The energy system within the E3ME model consists of equations for 23 fuel users (for instance chemical industry or air transport), and 12 fuel types (for instance electricity, or crude oil). Fifteen econometric regressions calibrated on data from 1970 to 2019 form the basis of the model. The model can be extended up to 2070. As a demand-led model, it first computes demand for final goods and services, and the supply of intermediate goods is estimated using input-output tables and bilateral trade relationships, which then drive employment, investment, income, induced productivity change, price levels and other macro variables 63 .

The IO tables are dynamically coupled to the FTT models via the energy balances. In specific, the coefficients for coal, oil and gas, manufactured fuels, electricity and “gas, steam & air conditioning” are adjusted based on the outcome of the FTT models.

The model uses World Bank estimates of historical GDP growth, the UN World Population Prospects for demographic change, and the IEA Energy Balances for energy demand growth, and the World Energy Outlook for baseline future energy demand 74 . The model does not incorporate the SSP framework, but our baseline can be compared most closely to SSP2 (the “middle of the road scenario” 38 . Philosophically, the model and SSP2 have the same narrative: a continuation of current trends.

Population growth in our model is slightly higher than SSP2, but economic growth is lower compared to SSP2 in many major economies (but always above SSP3). Total primary energy demand in 2050 is very similar to SSP2. For more details, see 61 .

Data availability

Historical generation and capacity of renewable energy from IRENA is available at https://irena.org/publications/2022/Apr/Renewable-Capacity-Statistics-2022 . Original data from BNEF and IEA are licensed by these owners, but datasets derived by the authors are available as part of the model code (see code availability). Source data for the figures are provided with this paper at https://doi.org/10.6084/m9.figshare.22659052 .

Code availability

The code for the standalone FTT model can be found at https://github.com/cpmodel/FTT_StandAlone/tree/Is_a_solar_future_inevitable 75 . This version was used for the uncertainty quantification of Figs.  3 and 5 . The computer code for the full E3ME-FTT model needed to replicate the study is licensed and not available publicly, but can be obtained from the authors upon reasonable request.

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Acknowledgements

JFM, FJMMN and PV received funding from the UK Department for Business, Energy and Industrial Strategy (BEIS) from the EEIST project. NA acknowledges support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 802891), a grant which also funded SK., FL and JR. We would like to thank Simon Sharpe for discussion that improved the discussion on policy implications. We would also like to thank Doyne Farmer for his valuable feedback.

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F.J.M.M.N. coordinated and performed the research, with contributions from J.-F.M., and N.A. F.J.M.M.N and J.-F.M. wrote the article with support from N.A., S.K. and F.L. N.A., F.L, S.K., and J.R. collected the BNEF data. F.J.M.M.N. led the model improvements and ran the simulations, with support from P.V., J.-F.M and H.P.

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Nijsse, F.J.M.M., Mercure, JF., Ameli, N. et al. The momentum of the solar energy transition. Nat Commun 14 , 6542 (2023). https://doi.org/10.1038/s41467-023-41971-7

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The Future of Solar Energy

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The Future of Solar Energy considers only the two widely recognized classes of technologies for converting solar energy into electricity — photovoltaics (PV) and concentrated solar power (CSP), sometimes called solar thermal) — in their current and plausible future forms. Because energy supply facilities typically last several decades, technologies in these classes will dominate solar-powered generation between now and 2050, and we do not attempt to look beyond that date. In contrast to some earlier Future of studies, we also present no forecasts — for two reasons. First, expanding the solar industry dramatically from its relatively tiny current scale may produce changes we do not pretend to be able to foresee today. Second, we recognize that future solar deployment will depend heavily on uncertain future market conditions and public policies — including but not limited to policies aimed at mitigating global climate change.

As in other studies in this series, our primary aim is to inform decision-makers in the developed world, particularly the United States. We concentrate on the use of grid-connected solar-powered generators to replace conventional sources of electricity. For the more than one billion people in the developing world who lack access to a reliable electric grid, the cost of small-scale PV generation is often outweighed by the very high value of access to electricity for lighting and charging mobile telephone and radio batteries. In addition, in some developing nations it may be economic to use solar generation to reduce reliance on imported oil, particularly if that oil must be moved by truck to remote generator sites. A companion working paper discusses both these valuable roles for solar energy in the developing world.

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How to write a research paper on solar energy: a graduate-level guide  0.

How many types of paper do you think a college student should know? Apart from writing essays, discussion posts, and replies, a person pursuing an undergraduate and graduate degree should be conversant with a format or outline of scientific papers, research proposals, and dissertations. This know-how assists a student in coherently organizing and structuring his or her ideas.

As such, this article aims to offer insightful tips on how to make a research paper on solar energy meet proficient or distinguished criteria on the rubric. In other words, this graduate-level guide provides a clear distinction between this type of writing and a general essay. 

Solar Energy Research Paper: A Recommended Structure 

When you review several research papers on solar energy, you’ll notice that an abstract appears before other sections. However, it’s important to note that a student should write it after completing the paper. Why should you adhere to this rule? Very simple, it’s because an abstract summarizes the key arguments of a research paper. This section, according to Naval Postgraduate School , differs from an executive summary in terms of length and information included. In particular, an abstract ranges from 100 to 200 words, while an executive summary might be 2 to 5 pages. What does this mean? A student might include citations in an executive summary. 

So, when writing a research paper on solar energy, you should ensure that its abstract contains concise statements about the following:

• The significance of the research 
• The research question
• The scientific method used to answer the research question
• The findings

Introduction

If you pride yourself on the knowledge of how to write a perfect essay, this section shouldn’t be a problem for you. When writing a solar energy research paper, you should present comprehensive theories underlying the problem. Take a close look at this paragraph.

Even though the discovery of fossil fuel to substitute wood charcoal promoted industrialization and economic development, it has presented multiple challenges to the environment and human health. According to Zoghi et al. (2017), as cited by Choifin et al.’s (2021) article, “most of the energy sources that are currently relied on are limited and will run out due to increasing demand” (p. 1). Due to the supply deficit of fossil fuel, many countries opt to purchase cheap fossil fuels. However, such petroleum contains high octane that reduces the lifespan of vehicle engines. As a consequence, nations end up with piles of scrap and heavy metals that pollute the environment. The country can remedy this problem if it implements renewable energy sources such as solar, hydropower, and wind power, among many other options. According to Biçen, Szczutkowski, and Vardar (2018), “solar energy, which is an almost infinite energy source that does not have a negative effect on the environment, is utilized in two ways as “Thermal Systems” and “Electrical Systems”.”

After reading this introduction, you’ll notice that the presented theoretical background of the problem contains scholarly pieces of evidence. Afterwards, it offers the significance of the research by highlighting why countries should adopt renewable sources of energy such as solar. 

Literature review

When writing a solar energy research paper, you should consider reviewing studies on the same subject. In this case, you can explore topics on the latest trends and the future. Take a look at the below literature review.

The expansion of solar energy solutions worldwide is attributable to its high demand. According to Solar Energy Industries Association [SEIA] (n.d.), this sector has experienced approximately 24% yearly growth over the past ten years. About 26 million houses benefit from over 149 gigawatts (GW) because of the federal financial support through the solar Investment Tax credit. Another reason for the expansion of this sector, according to Choifin et al. (2021), a suitable solution for the supply deficit of electricity is renewable energy sources (RE).

Ideally, your literature review should present arguments on different topics. Each paragraph should have at least two citations with ideas that build on a central theme. Depending on the length of your research paper, a literature review should contain several paragraphs. 

Methodology

Unlike a dissertation that a student has several weeks or months to complete, your professor might want you to complete a research paper on solar energy within days. As such, the recommended design would be a systematic review. In this case, you need to select a few journals on the topic of interest. How can you do this? Considering that you require access to articles with the latest information on solar energy, you can consider contacting professional services like CustomWritings to get your write my research paper request processed by expert writers. The reason for opting for a research paper writer on this website to assist you in systematic review concerns their experience of using online databases.  

While most systematic reviews on solar technology tend to be qualitative, you can opt to utilize mixed design. In this case, you can get some figures from the articles and conduct an extensive analysis to reveal some trends or patterns. At this point, you can consider including tables or graphs on the usage of renewable sources over the years.  

Discussions

After presenting the results, you need to support the trends and patterns with scholarly sources. You can find relevant articles by searching solar energy research paper topics on the web. The length of the discussion depends on your knowledge of interpreting results and summarizing evidence-based findings. 

While writing this section, you should ensure that it doesn’t look or structured similar to the abstract. As such, a student should summarize the main points of the study and the research implications. In some papers, you can combine discussion and conclusion. You can add recommendations in this section. 

References 

Regardless of your format, you should place all the materials cited in the paper in this section. 

Write a Research Paper on Solar Energy: Dos and Don’ts

• Use headings and subheadings . Unlike most essays, your research paper should have clear sections. This strategy facilitates the organization of ideas. 
• Define terms. Considering that you are most likely to apply technical writing in research papers, you should consider providing definitions of the vocabulary and figures used. This strategy is important when it comes to the result section.
• Cite all borrowed ideas . The rationale for citing and referencing concerns eliminating intentional plagiarism. 
• Let the research question guide the writing process . This strategy ensures that you stay on the topic.
• Fabricate the results. Since most research papers on solar energy tend to utilize secondary data, some students might provide fake data. 
• Overuse ‘I”. Although personal opinions are necessary when writing a research paper, you should devise a way of presenting them. 
• Introducing new results. When writing a discussion of a research paper, you should stick to your result. In other words, you should not get a source with similar information and just paraphrase. Make sure the information you are looking for either supports or challenges your results. 

Even though this article offers a standard structure for writing a research paper on solar energy, students should understand that any deviation in instruction is unacceptable. What does this mean? Some professors might require students to only look at the impact and consequences of solar energy. Such a research paper might have only two headings. It’s because of this reason you should always consult a research paper service if anything is unclear! 

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Efficacy of solar panels boosted

Solar energy is a crucial asset in the fight against climate change, and researchers at the University of Ottawa have devised a smart approach to optimize its effectiveness. Their innovative method includes incorporating artificial ground reflectors, a simple yet powerful enhancement.

The researchers found that by integrating these reflectors into solar setups, they could improve the system's energy production and efficiency, making such projects more economically viable. This discovery is significant in assessing the costs and benefits of using artificial reflectors in solar energy ventures.

To study how reflective ground covers affect solar energy output, the University of Ottawa's SUNLAB, led by electrical engineering Professor Karin Hinzer, who is also vice-dean, research of the Faculty of Engineering, collaborated with the National Renewable Energy Laboratory (NREL) in Golden, Colorado, a world leader in clean energy research, development, and deployment. The study, which was conducted by electrical engineering doctoral candidate Mandy Lewis in Golden, Colorado, found that placing reflective surfaces under solar panels can increase their energy output by up to 4.5%.

"We found that highly reflective white surfaces can boost solar power output," explains Mandy Lewis, the paper's lead author. "Critically, these reflectors should be placed directly under the solar panels, not between rows, to maximize this benefit."

Unlocking solar potential in Canada and beyond

These findings are particularly significant in Canada, where snow cover persists for three-to four months of the year in major cities like Ottawa and Toronto, and 65% of the country's vast landmass experiences snow cover for over half the year. Bifacial solar systems, paired with high ground reflectivity, offer tremendous potential in these regions. Additionally, given that approximately 4% of the world's land areas are classified as sandy deserts, this finding has global applications.

According to Lewis, "this research is crucial for maximizing solar energy production in geographically diverse locations. Furthermore, by generating more power per unit of land area, reflectors are ideal for densely populated areas, like city centres, where space limitations exist for solar installations."

This study marks the beginning of a new international research collaboration between the University of Ottawa and NREL. The project was funded by the National Sciences and Engineering Research Council of Canada (NSERC), Ontario Graduate Scholarships (OGS), and the US Department of Energy (DoE), underscoring the importance of collaborative efforts in advancing renewable energy technologies.

Global impact in facilitating the transition to clean energy

This research will contribute significantly to the global transition to zero-emission power sources. These findings hold particular value for Canada and other countries that are typically cloudy, since power gains of 6.0% were observed in cloudy Seattle compared to 2.6% in arid Tucson.

• Solar Energy
• Energy Technology
• Energy and Resources
• Energy Policy
• Energy and the Environment
• Renewable Energy
• Environmental Science
• Geomagnetic Storms
• Climate change mitigation
• Climate engineering
• Global climate model
• Global warming controversy
• Kyoto Protocol

Story Source:

Materials provided by University of Ottawa . Original written by Bernard Rizk. Note: Content may be edited for style and length.

Journal Reference :

• Mandy R. Lewis, Silvana Ovaitt, Byron McDanold, Chris Deline, Karin Hinzer. Artificial ground reflector size and position effects on energy yield and economics of single‐axis‐tracked bifacial photovoltaics . Progress in Photovoltaics: Research and Applications , 2024; DOI: 10.1002/pip.3811

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The Evolution Of Solar Energy: How Solar Panels Have Changed Over The Years

T he landscape of solar energy production and use is widespread and comprehensively developed today. Sure, research still hasn't created a consistently efficient means of storing solar power in the long term. But photovoltaic (PV) cells do translate solar power into electrical energy that can be used to charge (and then discharge) lithium-ion batteries, among others, though efficiency loss along the way can make it a challenge for residential users. Even so, solar farms around the country and world have transformed the way humans produce electrical energy, and residential systems are delivering increased energy independence alongside improved environmental security.

The journey from early exploits in harvesting the sun's energy to this present moment and beyond is a fascinating one. Ancient humans harnessed our star's potential in many ways, and modern inhabitants of the Earth have followed suit, albeit with increasingly impressive technological breakthroughs that make the sun increasingly valuable. The contemporary solar panel owes its existence to a long string of advancements that begin far back in history — but really came into their own over the last couple hundred years. This is the evolution of the solar panel.

Read more: 5 Of The Best RV Deep Cycle Battery Brands, Ranked

Harvesting The Sun's Rays In Antiquity

As early as the 7th century B.C., humans were using the sun to start fires with the help of rudimentary magnifying glass technology. These experiments with solar power set the baseline for humanity's partnership with the sky's ancient energy producer, and they stand the test of time — young students still go outside to create heat and tiny burn marks under the supervision of their teachers. Thousands of years after those early harnessers, Chinese and Greek civilizations built cities with the sun's position in mind. 

These communities crafted homes and gathering places directly affected by the sun's position in the sky, changing them throughout the year to accommodate weather patterns and comfort requirements. They used the sun's trajectory and the year's seasonal pattern to harness the star's heat during the winter and create a cooling effect in the summer months. These early efforts to capture the sun's radiant energy colored the way humans thought about the celestial body for centuries to come. It would be thousands of years before humanity found that it could truly capture and manipulate the sun's energy, but that voyage starts here, in antiquity's first steps.

The First Solar Cell Is Developed In 1767

Solar energy was conceptualized in a whole new light after Horace Benedicte de Saussure created the first cell in 1767. The Swiss intellectual began toying with a design for solar capture that might help harness the sun's energy. Saussure is famous for exploring the Alps and performing a range of geological testing and measurements. In 1767, he created the heliothermometer, a device that magnified incoming sunlight to produce an increased heat output. Saussure's heliothermometer was constructed of layered glass in an insulated box. Essentially the device acted like a small greenhouse that would gradually raise the temperature so that the sun's light energy could be transformed into heat. The device amplified the heat enough to reach 108 degrees Celsius, breaching the boiling point of water and allowing users to leverage the sun's energy for cooking and other rudimentary tasks.

At this point, solar capture technology obviously wasn't very efficient, but Saussure's breakthrough laid the foundation for all other solar cell technologies that arrived over the next 250-plus years. It might be hard to believe that this cutting-edge technology got its start such a long time ago, but it really begins here with the understanding of how to reliably convert sunlight into a usable alternative energy format.

Featured image by Jens Juel via Wikimedia Commons | Cropped and scaled | Public domain]

The Photovoltaic Effect Is Discovered In 1839

In 1839, roughly 70 years after the first solar cell was created, Edmond Becquerel observed the photovoltaic effect in action, kick-starting a revolution in human understanding of solar energy — and power production and usage more broadly. At this point, experimentation with electrical power is in full swing, although the first American power grid technology was still a few decades away. The photovoltaic effect is a foundational principle underpinning the very existence of modern solar technology. In a nutshell, Becquerel observed that certain materials produce electric current when they're exposed to sunlight or even radiant heat.

At just 19, Becquerel made this breakthrough while researching in his father's lab. After this inflection point, it became clear that solar capture technology doesn't require an additional translation of energy to utilize the resource after it has been collected as light. Early solar capture revolved around creating heat, but this must be translated again in order to develop an electric charge that might power a machine, light bulb, or automotive vehicle. With each conversion, energy is lost — another foundational principle — meaning the ability to generate electrical current directly from collected sunlight saved incredible space, time, and energy itself.

[Featured image by Nadar via Wikimedia Commons  | Cropped and scaled | Public Domain]

1883: Charles Fritts Builds A Modern Solar Capture Cell

The selenium cell is the next major breakthrough for solar power production. Charles Fritts continued the progress of many other inventors in the arena, settling on selenium after other pioneering research into its photoconductivity. In 1883, Fritts successfully created the first solid material solar cell, requiring no moving parts to capture sunlight and output an electric charge that could be harnessed to support human needs.

Fritts' cell created electricity at an efficiency conversion rate of about 1% or 2%, but it was the breakthrough required for crafting increasingly useful electricity-generating solar cells. As reported by Smithsonian Magazine , Fritts joyfully noted of his selenium creation that it produced an electric current that was "continuous, constant, and of considerable force." The improvement made for a major leap forward in solar power creation. No longer did users have to rely on bulky productions or moving components that made the tool far more complicated. The solar cell was coming into form.

Photoelectric Processes Are Observed And Improved Cells Make Their Appearance

Building on the existing principles of the photovoltaic effect, a similar phenomenon — photoelectric effect — was observed in 1887 by German physicist Heinrich Hertz. This is when electrons are emitted into space rather than entering what is known as the conduction band of the material in question. Hertz noticed that shining UV light on the nodes created sparks between electrodes, eventually uncovering this related phenomenon.

A year later, Aleksandr Stoletov had built a working photoelectric cell, the first of its kind. Perhaps the most important feature of this competing design was found in Hertz's discovery that more electric power is created from exposure to ultraviolet light than in the visible spectrum. Considering the vast, radiant output of UV rays from the sun, this new finding and resulting breakthrough created an exciting new avenue to pursue in the quest for ever-increasing solar power efficiency and functionality.

[Featured image by James Edward Henry Gordon via Wikimedia Commons | Cropped and scaled | Public domain]

Silicon Solar Cells Hit Commercial Production

Steady progress continued after these early breakthroughs, but explosive growth began to take root in the 1950s. Early in the decade, Bell Laboratories developed the silicon solar cell, bringing energy-producing efficiency up to 6%. Still notably lower than modern residential efficiency standards (around 20%), this was a big change from the low numbers that the first wave of solar collection tools were able to muster. Indeed, cells of this era were suddenly capable of powering equipment used in labs, homes, and elsewhere. In 1958, solar collection tools were deployed in space exploration equipment to provide consistent power to devices that would live out in the great beyond alongside their energy progenitor.

The boost in production efficiency was due in large part to the inclusion of silicon in the design rather than the earlier use of selenium. It offered greater efficiency, but at this stage the costs remained prohibitive for all but the most specialized uses. Case in point: In 1958 NASA launched Vanguard 1, a satellite that has now traveled nearly 200,000 times around the Earth on the backs of photoelectric solar panels. Research and specialty uses remained the overwhelming use of solar technology, but changes were stirring behind the scenes.

[Featured image by NASA via Wikimedia Commons | Cropped and scaled | Public domain]

Exxon Corporation Research Pours Money Into The Technology

Throughout its time in contemporary existence, solar power has faced off against two mortal threats. In the technology's modern framework, price and efficiency act as dual barriers to comprehensive adoption and severely challenge any model of environmental and power grid sustainability that relies primarily on solar to supplant environmentally damaging practices. Coal-fired industrial production might be dirty and unsustainable over the long term, but the excessive costs associated with building solar collectors and then running them at an abysmal efficiency rating make it a non-starter in the present.

In the 1970s, things began to shift in both regards, however. Exxon Corporation research began taking off, and the U.S. government got serious about projects designed to create more robust energy independence. The Solar Energy Research, Development, and Demonstration Act of 1974 saw federal dollars poured into solar projects aimed at making solar practical and affordable so the public could easily access the benefits of this new energy option. Meanwhile, Exxon's studies focused on reducing costs, and the company succeeded in reducing the price of solar-created electricity down from $100 per watt to as low as $20. This still wasn't enough to make it directly competitive with its alternatives, but the framework for a viable path forward was certainly beginning to take shape.

[Featured image by Boyd Norton via Wikimedia Commons  | Cropped and scaled | Public domain]

20% Efficiency Is Achieved In 1985

The second barrier to widespread adoption came in the form of efficiency. Wave energy capture technology has recently found ways to deal with this issue, and in 1985, it appeared that solar cells had as well. The University of South Wales broke the 20% barrier in silicon cells in 1985, and solar buildings, parks, and other large-scale construction projects were cropping up all over the country and globe around this time, too. It's also important to note that the 1980s saw another wave of crippling energy crisis years, spurring a global economic recession.

Just a few years earlier, in 1982, the first solar-powered car was driven from Sydney to Perth (around 2,800 miles) in half the time it took the first gasoline-powered car to achieve the feat. Global adoption rose past 21.3 megawatts of production in 1983, as well. In 1992, a decade after these new developments, researchers at the University of South Florida broke the 15% efficiency barrier for the first time with a thin-film photovoltaic solar cell (made of cadmium telluride and clocking in at 15.9% efficiency). A year after that development Pacific Gas & Electric installed the first grid-supported photovoltaic system. It was a 500-kilowatt endeavor in Kerman, California, and the first solar-distributed power system built. Another year later, the National Renewable Energy Laboratory broke the 30% energy conversion threshold with a new solar cell design that utilized gallium indium phosphide and gallium arsenide.

[Featured image by Nikos Kopidakis via Wikimedia Commons  | Cropped and scaled | Public domain] 

By 2010, Solar Power Production Is Booming Across The United States

As Boston University Institute for Global Sustainability  documents, power production through solar technology has exploded in the United States over the last two decades. The introduction of the Solar Investment Tax Credit in 2006 spurred a major shift in the way enterprise and residential power production and usage was considered, and by 2010 solar power production had become a nearly monolithic new opportunity. In North Carolina — and California, specifically — new solar power construction projects jump off the map. Following these early adopters, the Maryland and New Jersey-New York coastline and a smattering of insular communities in Colorado, New Mexico, and across the Midwest began to see massive investment in solar power construction.

These projects have brought gigantic financial investment into communities that may have formerly relied on coal mining, oil drilling, fracking, and other formats of energy harvesting. An evolution of the energy sector's workforce began taking place around 2010, and it hasn't slowed down in the 14 years since. In coordination with the 2006 legislation, 2009 saw the American Recovery and Reinvestment Act signed into law, expanding tax breaks, grants, and other incredible financial incentives for companies to develop solar power infrastructure.

Tax Incentives Today Make Residential Solar Energy A True Option

Today, the efficiency of most  residential solar panels  sits at around the 20% mark, on average. With prices continuing to drop — a 70% reduction in the price of installation over a 10-year period around the time of key legislative victories for the burgeoning solar industry — residential panels are increasingly viable. In fact, the Office of Energy Efficiency & Renewable Energy  reported in 2017 that the solar industry created roughly 1,000 new jobs every week. In addition, tax breaks and other financial incentives extended to residential users have made it an affordable solution in both the here and now, and over the long term as a means to reduce continuing energy usage costs. Current tax incentives offer up to a 30% recovery of installation costs, running between 2017 and 2034, with rollover credits available to installing homeowners (and perhaps even solar-installing renters ) so that they can utilize the full financial value.

Those who have installed solar panels on their homes can also take advantage of banking, net metering, and energy sell backs, as well. With added battery technology in the home, residential users can now bank surplus energy captured through the home system. States have also mandated that users can sell back the surplus energy generated to their power company for an added offset to their electricity bill. Continued technological improvement and government programs have made solar power a truly valuable option both in the commercial and residential space.

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Concepts for gargantuan space-based solar power plants have swung back in vogue. But the engineering to make them a reality still lags far behind.

The accelerating buildout of solar farms on Earth is already hitting speed bumps, including public pushback against the large tracts of land required and a ballooning backlog of requests for new transmission lines and grid connections. Energy experts have been warning that electricity is likely to get more expensive and less reliable unless renewable power that waxes and wanes under inconstant sunlight and wind is backed up by generators that can run whenever needed. To space enthusiasts, that raises an obvious question: Why not stick solar power plants where the sun always shines?

Space-based solar power is an idea so beautiful, so tantalizing that some argue it is a wish worth fulfilling. A constellation of gigantic satellites in geosynchronous orbit (GEO) nearly 36,000 kilometers above the equator could collect sunlight unfiltered by atmosphere and uninterrupted by night (except for up to 70 minutes a day around the spring and fall equinoxes). Each megasat could then convert gigawatts of power into a microwave beam aimed precisely at a big field of receiving antennas on Earth. These rectennas would then convert the signal to usable DC electricity.

The thousands of rocket launches needed to loft and maintain these space power stations would dump lots of soot, carbon dioxide, and other pollutants into the stratosphere, with uncertain climate impacts. But that might be mitigated, in theory, if space solar displaced fossil fuels and helped the world transition to clean electricity.

The glamorous vision has inspired numerous futuristic proposals. Japan’s space agency has presented a road map to deployment. Space authorities in China aim to put a small test satellite in low Earth orbit (LEO) later this decade. Ideas to put megawatt-scale systems in GEO sometime in the 2030s have been floated but not yet funded.

The U.S. Naval Research Laboratory has already beamed more than a kilowatt of power between two ground antennas about a kilometer apart. It also launched in 2023 a satellite that used a laser to transmit about 1.5 watts, although the beam traveled less than 2 meters and the system had just 11 percent efficiency. A team at Caltech earlier this year wrapped up a mission that used a small satellite in LEO to test thin-film solar cells, flexible microwave-power circuitry, and a small collapsible deployment mechanism. The energy sent Earthward by the craft was too meager to power a lightbulb, but it was progress nonetheless.

The European Space Agency (ESA) debuted in 2022 its space-based solar-power program, called Solaris, with an inspiring (but entirely fantastical) video animation . The program’s director, Sanjay Vijendran , told IEEE Spectrum that the goal of the effort is not to develop a power station for space. Instead, the program aims to spend three years and €60 million (US $65 million) to figure out whether solar cells, DC-to-RF converters, assembly robots, beam-steering antennas, and other must-have technologies will improve drastically enough over the next 10 to 20 years to make orbital solar power feasible and competitive. Low-cost, low-mass, and space-hardy versions of these technologies would be required, but engineers trying to draw up detailed plans for such satellites today find no parts that meet the tough requirements.

With the flurry of renewed attention, you might wonder: Has extraterrestrial solar power finally found its moment? As the recently retired head of space power systems at ESA—with more than 30 years of experience working on power generation, energy storage, and electrical systems design for dozens of missions, including evaluation of a power-beaming experiment proposed for the International Space Station—I think the answer is almost certainly no.

Despite mounting buzz around the concept, I and many of my former colleagues at ESA are deeply skeptical that these large and complex power systems could be deployed quickly enough and widely enough to make a meaningful contribution to the global energy transition. Among the many challenges on the long and formidable list of technical and societal obstacles: antennas so big that we cannot even simulate their behavior.

Here I offer a road map of the potential chasms and dead ends that could doom a premature space solar project to failure. Such a misadventure would undermine the credibility of the responsible space agency and waste capital that could be better spent improving less risky ways to shore up renewable energy, such as batteries, hydrogen, and grid improvements. Champions of space solar power could look at this road map as a wish list that must be fulfilled before orbital solar power can become truly appealing to electrical utilities.

Space Solar Power at Peak Hype—Again

For decades, enthusiasm for the possibility of drawing limitless, mostly clean power from the one fusion reactor we know works reliably—the sun—has run hot and cold. A 1974 study that NASA commissioned from the consultancy Arthur D. Little bullishly recommended a 20-year federal R&D program, expected to lead to a commercial station launching in the mid-1990s. After five years of work, the agency delivered a reference architecture for up to 60 orbiting power stations, each delivering 5 to 10 gigawatts of baseload power to major cities. But officials gave up on the idea when they realized that it would cost over $1 trillion (adjusted for inflation) and require hundreds of astronauts working in space for decades, all before the first kilowatt could be sold.

NASA did not seriously reconsider space solar until 1995, when it ordered a “fresh look” at the possibility. That two-year study generated enough interest that the U.S. Congress funded a small R&D program, which published plans to put up a megawatt-scale orbiter in the early 2010s and a full-size power plant in the early 2020s. Funding was cut off a few years later, with no satellites developed.

Then, a decade ago, private-sector startups generated another flurry of media attention. One, Solaren, even signed a power-purchase agreement to deliver 200 megawatts to utility customers in California by 2016 and made bold predictions that space solar plants would enter mass production in the 2020s. But the contract and promises went unfulfilled.

The repeated hype cycles have ended the same way each time, with investors and governments balking at the huge investments that must be risked to build a system that cannot be guaranteed to work. Indeed, in what could presage the end of the current hype cycle, Solaris managers have had trouble drumming up interest among ESA’s 22 member states. So far only the United Kingdom has participated, and just 5 percent of the funds available have been committed to actual research work.

Even space-solar advocates have recognized that success clearly hinges on something that cannot be engineered: sustained political will to invest, and keep investing, in a multidecade R&D program that ultimately could yield machines that can’t put electricity on the grid. In that respect, beamed power from space is like nuclear fusion, except at least 25 years behind.

In the 1990s, the fusion community succeeded in tapping into national defense budgets and cobbled together the 35-nation, $25 billion megaproject ITER, which launched in 2006. The effort set records for delays and cost overruns, and yet a prototype is still years from completion. Nevertheless, dozens of startups are now testing new fusion-reactor concepts . Massive investments in space solar would likely proceed in the same way. Of course, if fusion succeeds, it would eclipse the rationale for solar-energy satellites.

Space Industry Experts Run the Numbers

The U.S. and European space agencies have recently released detailed technical analyses of several space-based solar-power proposals. [See diagrams.] These reports make for sobering reading.

SPS-ALPHA Mark-III

Chris Philpot

Proposed by: John C. Mankins, former NASA physicist

Features: Thin-film reflectors (conical array) track the sun and concentrate sunlight onto an Earth-facing energy-conversion array that has photovoltaic (PV) panels on one side, microwave antennas on the other, and power distribution and control electronics in the middle. Peripheral modules adjust the station’s orbit and orientation.

Proposed by : China Academy of Space Technology

Features : Fifty PV solar arrays, each 200 meters wide and 600 meters long, track the sun and send power through rotating high-power joints and perpendicular trusses to a central microwave-conversion and transmission array that points 128,000 antenna modules at the receiving station on Earth.

Proposed by: Ian Cash, chief architect, Space Solar Group Holdings

Features: Circular thin-film reflectors track the sun and bounce light onto a helical array that includes myriad small PV cells covered by Fresnel-lens concentrators, power-conversion electronics, and microwave dipole antennas. The omnidirectional antennas must operate in sync to steer the beam as the station rotates relative to the Earth.

SPS (Solar power satellite)

Proposed by: Thales Alenia Space

Features: Nearly 8,000 flexible solar arrays, each 10 meters wide and 80 meters long, are unfurled from roll-out modules and linked together to form two wings. The solar array remains pointed at the sun, so the central transmitter must rotate and also operate with great precision as a phased-array antenna to continually steer the beam onto the ground station.

Electricity made this way, NASA reckoned in its 2024 report , would initially cost 12 to 80 times as much as power generated on the ground, and the first power station would require at least $275 billion in capital investment. Ten of the 13 crucial subsystems required to build such a satellite—including gigawatt-scale microwave beam transmission and robotic construction of kilometers-long, high-stiffness structures in space—rank as “high” or “very high” technical difficulty, according to a 2022 report to ESA by Frazer-Nash , a U.K. consultancy. Plus, there is no known way to safely dispose of such enormous structures, which would share an increasingly crowded GEO with crucial defense, navigation, and communications satellites, notes a 2023 ESA study by the French-Italian satellite maker Thales Alenia Space.

An alternative to microwave transmission would be to beam the energy down to Earth as reflected sunlight. Engineers at Arthur D. Little described the concept in a 2023 ESA study in which they proposed encircling the Earth with about 4,000 aimable mirrors in LEO. As each satellite zips overhead, it would shine an 8-km-wide spotlight onto participating solar farms, allowing the farms to operate a few extra hours each day (if skies are clear). In addition to the problems of clouds and light pollution, the report noted the thorny issue of orbital debris, estimating that each reflector would be penetrated about 75 billion times during its 10-year operating life.

My own assessment, presented at the 2023 European Space Power Conference and published by IEEE , pointed out dubious assumptions and inconsistencies in four space-solar designs that have received serious attention from government agencies. Indeed, the concepts detailed so far all seem to stand on shaky technical ground.

Massive Transmitters and Receiving Stations

The high costs and hard engineering problems that prevent us from building orbital solar-power systems today arise mainly from the enormity of these satellites and their distance from Earth, both of which are unavoidable consequences of the physics of this kind of energy transmission. Only in GEO can a satellite stay (almost) continuously connected to a single receiving station on the ground. The systems must beam down their energy at a frequency that passes relatively unimpeded through all kinds of weather and doesn’t interfere with critical radio systems on Earth. Most designs call for 2.45 or 5.8 gigahertz, within the range used for Wi-Fi. Diffraction will cause the beam to spread as it travels, by an amount that depends on the frequency.

Thales Alenia Space estimated that a transmitter in GEO must be at least 750 meters in diameter to train the bright center of a 5.8-GHz microwave beam onto a ground station of reasonable area over that tremendous distance—65 times the altitude of LEO satellites like Starlink. Even using a 750-meter transmitter, a receiver station in France or the northern United States would fill an elliptical field covering more than 34 square kilometers. That’s more than two-thirds the size of Bordeaux, France, where I live.

“Success hinges on something that cannot be engineered: sustained political will to keep investing in a multidecade R&D program that ultimately could yield machines that can’t put electricity on the grid.”

Huge components come with huge masses, which lead to exorbitant launch costs. Thales Alenia Space estimated that the transmitter alone would weigh at least 250 tonnes and cost well over a billion dollars to build, launch, and ferry to GEO. That estimate, based on ideas from the Caltech group that have yet to be tested in space, seems wildly optimistic; previous detailed transmitter designs are about 30 times heavier.

Because the transmitter has to be big and expensive, any orbiting solar project will maximize the power it sends through the beam, within acceptable safety limits. That’s why the systems evaluated by NASA, ESA, China, and Japan are all scaled to deliver 1–2 GW, the maximum output that utilities and grid operators now say they are willing to handle. It would take two or three of these giant satellites to replace one large retiring coal or nuclear power station.

Energy is lost at each step in the conversion from sunlight to DC electricity, then to microwaves, then back to DC electricity and finally to a grid-compatible AC current. It will be hard to improve much on the 11 percent end-to-end efficiency seen in recent field trials. So the solar arrays and electrical gear must be big enough to collect, convert, and distribute around 9 GW of power in space just to deliver 1 GW to the grid. No electronic switches, relays, and transformers have been designed or demonstrated for spacecraft that can handle voltages and currents anywhere near the required magnitude.

Some space solar designs, such as SPS-ALPHA and CASSIOPeiA , would suspend huge reflectors on kilometers-long booms to concentrate sunlight onto high-efficiency solar cells on the back side of the transmitter or intermingled with antennas. Other concepts, such as China’s MR-SPS and the design proposed by Thales Alenia Space, would send the currents through heavy, motorized rotating joints that allow the large solar arrays to face the sun while the transmitter pivots to stay fixed on the receiving station on Earth.

The net result, regardless of approach, is an orbiting power station that spans several kilometers, totals many thousands of tonnes, sends gigawatts of continuous power through onboard electronics, and comprises up to a million modules that must be assembled in space—by robots. That is a gigantic leap from the largest satellite and solar array ever constructed in orbit: the 420-tonne, 109-meter International Space Station (ISS), whose 164 solar panels produce less than 100 kilowatts to power its 43 modules.

The ISS has been built and maintained by astronauts, drawing on 30 years of prior experience with the Salyut, Skylab, and Mir space stations. But there is no comparable incremental path to a robot-assembled power satellite in GEO. Successfully beaming down a few megawatts from LEO would be an impressive achievement, but it wouldn’t prove that a full-scale system is feasible, nor would the intermittent power be particularly interesting to commercial utilities.

T Minus...Decades?

NASA’s 2024 report used sensitivity analysis to look for advances, however implausible, that would enable orbital solar power to be commercially competitive with nuclear fission and other low-emissions power. To start, the price of sending a tonne of cargo to LEO on a large reusable rocket, which has fallen 36 percent over the past 10 years, would have to drop by another two-thirds, to $500,000. This assumes that all the pieces of the station could be dropped off in low orbit and then raised to GEO over a period of months by space tugs propelled by electrical ion thrusters rather than conventional rockets. The approach would slow the pace of construction and add to the overall mass and cost. New tugs would have to be developed that could tow up to 100 times as much cargo as the biggest electric tugs do today. And by my calculations, the world’s annual production of xenon—the go-to propellant for ion engines—is insufficient to carry even a single solar-power satellite to GEO.

Thales Alenia Space looked at a slightly more realistic option: using a fleet of conventional rockets as big as SpaceX’s new Starship—the largest rocket ever built—to ferry loads from LEO to GEO, and then back to LEO for refueling from an orbiting fuel depot. Even if launch prices plummeted to $200,000 a tonne, they calculated, electricity from their system would be six times as expensive as NASA’s projected cost for a terrestrial solar farm outfitted with battery storage—one obvious alternative.

What else would have to go spectacularly right? In NASA’s cost-competitive scenario, the price of new, specialized spaceships that could maintain the satellite for 30 years—and then disassemble and dispose of it—would have to come down by 90 percent. The efficiency of commercially produced, space-qualified solar cells would have to soar from 32 percent today to 40 percent, while falling in cost. Yet over the past 30 years, big gains in the efficiency of research cells have not translated well to the commercial cells available at low cost [see chart, “Not So Fast”].

Is it possible for all these things to go right simultaneously? Perhaps. But wait—there’s more that can go wrong.

The Toll of Operating a Solar Plant in Space

Let’s start with temperature. Gigawatts of power coursing through the system will make heat removal essential because solar cells lose efficiency and microcircuits fry when they get too hot. A couple of dozen times a year, the satellite will pass suddenly into the utter darkness of Earth’s shadow, causing temperatures to swing by around 300 °C, well beyond the usual operating range of electronics. Thermal expansion and contraction may cause large structures on the station to warp or vibrate.

Then there’s the physical toll of operating in space. Vibrations and torques exerted by altitude-control thrusters, plus the pressure of solar radiation on the massive sail-like arrays, will continually bend and twist the station this way and that. The sprawling arrays will suffer unavoidable strikes from man-made debris and micrometeorites, perhaps even a malfunctioning construction robot. As the number of space power stations increases, we could see a rapid rise in the threat of Kessler syndrome , a runaway cascade of collisions that is every space operator’s nightmare.

Probably the toughest technical obstacle blocking space solar power is a basic one: shaping and aiming the beam. The transmitter is not a dish, like a radio telescope in reverse. It’s a phased array, a collection of millions of little antennas that must work in near-perfect synchrony, each contributing its piece to a collective waveform aimed at the ground station.

Like people in a stadium crowd raising their arms on cue to do “the wave,” coordination of a phased array is essential. It will work properly only if every element on the emitter syncs the phase of its transmission to align precisely with the transmission of its neighbors and with an incoming beacon signal sent from the ground station. Phase errors measured in picoseconds can cause the microwave beam to blur or drift off its target. How can the system synchronize elements separated by as much as a kilometer with such incredible accuracy? If you have the answer, please patent and publish it, because this problem currently has engineers stumped.

There is no denying the beauty of the idea of turning to deep space for inexhaustible electricity. But nature gets a vote. As Lao Tzu observed long ago in the Tao Te Ching , “The truth is not always beautiful, nor beautiful words the truth.”

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Henri Barde joined the European Space Agency in 2007 and served as head of the power systems, electromagnetic compatibility, and space environment division until his retirement in 2017. He remains active as an expert consultant to ESA and the European Commission. Prior to ESA, Barde worked in various engineering roles in the space industry for 27 years at MATRA Espace, which became EADS Astrium and is now Airbus Defence and Space. 

I talk with space solar power advocates, saying similar things since 1975. There's 3.84e20 watts of "free" sunlight Out There. Tempting to bring some home. Frightening to ponder sidelobe intermodulation in radar/communication microwave LNAs.

Instead, I suggest KW/MW/GW scientific computation arrays in space; PV-powered, beaming data results to Earth, and dissipating heat into the 2.7 void, . ULSI silicon chips and direct-bandgap PV are gossamer, receive bits can be less than 10kT, many tasks can be small-chip parallelizable and redundant, nanometer FETs are intrinsically rad-hard. Why not?

http://server-sky.com

Not a mention in the article about safety. What about the aiming of the satellite going bad and whole towns being fried like our dinner! Personally, I don't want a GW of energy over my house.

Management Versus Technical Track

Femtosecond lasers solve solar panels' recycling issue, augmented reality slims down with ai and holograms.