When sunshine became cheaper than coal

In a study published in Energy and Environment Materials, researchers from Surrey's Advanced Technology Institute (ATI) argue that solar photovoltaic (PV) technology is now the key driver of the world's transition to clean, renewable power.

Professor Ravi Silva, co-author of the study and Director of the ATI at the University of Surrey, said:

"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."

The research team also found that the price of lithium-ion batteries has fallen by 89% since 2010, making solar-plus-storage systems as cost-effective as gas power plants. These hybrid setups, which combine solar panels with batteries, are now standard in many regions and allow solar energy to be stored and released when needed, turning it into a more reliable, dispatchable source of power that helps balance grid demand.

Despite many reasons to be optimistic, the ATI research team points to several challenges - particularly connecting large amounts of solar power to existing electricity networks. In some regions, such as California and China, high solar generation has led to grid congestion and wasted energy when supply exceeds demand.

Dr Ehsan Rezaee, co-author of the study from the University of Surrey, comments:

"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."

Professor Silva added:

"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.

"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."