When sunshine became cheaper than coal

Published in Energy and Environment Materials, the study from Surrey's Advanced Technology Institute (ATI) highlights how solar photovoltaic (PV) technology has become the driving force behind the global shift toward clean, renewable energy.

Professor Ravi Silva, the ATI's Director and co-author of the study, explained:

"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 researchers also reported that the price of lithium-ion batteries has dropped by 89% since 2010, making solar systems with built-in storage as economical as gas plants. These solar-plus-storage systems, which combine panels with batteries, are now widely used and allow solar power to be stored for use at any time. This makes solar a more dependable energy source that can help stabilize power grids and meet demand more efficiently.

While the outlook is positive, the team cautioned that integrating large-scale solar energy into existing power grids remains a major challenge. In regions such as California and China, high solar output has sometimes led to grid congestion and wasted energy when generation exceeds demand.

Dr. Ehsan Rezaee, a co-author of the study, said:

"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."