Solar energy has become so affordable that, in the sunniest regions, generating one unit of electricity can cost as little as £0.02, making it cheaper than power from coal, gas, or even wind. That’s according to a new study from the University of Surrey.
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Published in Energy and Environment Materials, the research from Surrey’s Advanced Technology Institute (ATI) highlights solar photovoltaic (PV) technology as a leading force in the global shift toward clean, renewable energy. The findings suggest that continued investment in solar could significantly accelerate efforts to reduce carbon emissions and lower energy costs worldwide.
Even here in the UK, a country that sits 50 degrees north of the equator, solar is the cheapest option for large-scale energy generation. Globally, the total amount of solar power installed passed 1.5 terawatts in 2024 – twice as much as in 2020 and enough to power hundreds of millions of homes. Simply put, this technology is no longer a moonshot prospect but a foundational part of the resilient, low-carbon energy future that we all want to bring to reality.
Ravi Silva, Study Co-Author, Professor and Director, Advanced Technology Institute, University of Surrey
The researchers also noted a dramatic drop in the cost of lithium-ion batteries, down 89 % since 2010, which has made solar-plus-storage systems as affordable as gas-fired power plants. These hybrid setups, which pair solar panels with battery storage, are now widely adopted in many regions. By storing excess energy and releasing it when needed, they turn solar into a more reliable, dispatchable power source capable of helping balance supply and demand on the grid.
However, the study also highlights some pressing challenges. Chief among them is integrating large volumes of solar power into existing electricity networks. In areas like California and China, for instance, high levels of solar generation have led to grid congestion and energy being wasted when supply outpaces demand.
Connecting growing levels of solar power to electricity networks is now one of the biggest challenges. Smart grids, artificial intelligence forecasting, and stronger links between regions will be vital to keep power systems stable as renewable energy use rises.
Dr. Ehsan Rezaee, Study Co-Author, University of Surrey
“With the integration of energy storage and smart grid technologies, solar is now capable of delivering reliable, affordable, and clean power at scale. Innovations in materials such as perovskite solar cells could boost energy output by up to 50% without increasing land use,” added Professor Silva.
“However, progress will depend on consistent, long-term policy support. Initiatives such as the Inflation Reduction Act in the US, the EU’s REPowerEU plan, and India’s Production Linked Incentive scheme show how clear direction can drive investment and innovation. Sustained commitment and international collaboration will be essential if we are to accelerate the world’s transition to a clean and reliable energy system,” concluded Professor Silva.
Journal Reference:
Rezaee, E., et al. (2025) Solar Energy in 2025: Global Deployment, Cost Trends, and the Role of Energy Storage in Enabling a Resilient Smart Energy Infrastructure. Energy & Environmental Materials. doi.org/10.22541/au.175647950.09188768/v1