Solar vs Fossil Fuels: The IEA's Global Energy Review 2026

The global energy system underwent a noticeable shift last year.

For the first time ever, a renewable energy source – solar – delivered the largest share of growth in global energy demand.

This landmark finding comes from the International Energy Agency’s Global Energy Review 2026, published earlier this month, which analyses data from 2025. Solar power alone accounted for more than a quarter of the world’s additional energy demand last year, a milestone that would have seemed unlikely just ten years ago.

The broader energy demand picture also evolved.

Global demand rose by 1.3% in 2025, marking a slowdown compared to the 2% growth seen in 2024. This moderation was partly driven by milder weather in key regions, incremental gains in energy efficiency and weaker growth across some energy-intensive industries.

Solar surges but fossil fuels persist

Solar’s headline performance stands out: generation increased by an impressive 600TWh in 2025, the largest annual rise ever recorded for any power source outside of post-crisis rebounds.

That increase alone met around 70% of the global rise in electricity generation.

Yet the wider energy mix tells a more complex story than solar’s success alone suggests. Coal remained the world’s largest source of electricity, responsible for 34% of total generation in 2025. At the same time, global energy-related CO₂ emissions continued to climb, reaching a record high of nearly 38.4 billion tonnes – up 0.4% year-on-year.

Natural gas played a major role in that increase, contributing roughly 85 million tonnes of the 185 million tonne rise in combustion-related CO₂ emissions.

Regional divides widen

The US broke from a decade-long pattern in a way likely to concern climate advocates.
Energy demand rose by more than 2% in 2025 – the second-fastest increase since 2000 outside of post-recession rebounds.

This was driven partly by a severe winter, alongside robust industrial output and rapidly growing electricity demand from data centres, which accounted for around half of total demand growth. Higher gas prices also led to a shift back towards coal, pushing US coal demand up by 10% after years of decline.

In China, coal-fired generation declined for only the second time since the 1970s, as growth in renewables and nuclear capacity outpaced overall demand increases.

Elsewhere, India recorded near-flat CO₂ emissions for the first time since the 1970s. However, the IEA notes that this was largely due to an unusually strong monsoon season, rather than purely structural changes in the energy system.

EV momentum accelerates

Sustainable mobility also saw major developments.
Global electric vehicle sales surpassed 20 million units in 2025, meaning one in every four new cars sold was electric.

In China, EVs made up more than 50% of annual car sales for the first time.

Europe emerged as the fastest-growing major EV market, with sales across the EU increasing by 30%.

By contrast, the US experienced a 2% decline in EV sales, likely linked to President Donald Trump’s decision to remove federal tax credits in the latter half of the year.

Storage expands, nuclear holds steady

In climate technology, battery storage stood out as the fastest-growing power technology.
A total of 108GW of new capacity was added globally, representing a 40% increase compared to 2024.

Nuclear capacity, meanwhile, remained stable at 420GW, as 3GW of new additions were offset by plant retirements.

However, momentum may be building: construction began on more than 12GW of new nuclear capacity during the year, with countries including the UK signalling renewed interest in nuclear power.

A deeper transition?

According to the IEA, the combined deployment of solar, wind, nuclear, electric vehicles and heat pumps since 2019 is now avoiding more than 35 exajoules of fossil fuel demand annually – equivalent to around 7% of global fossil fuel consumption.

That is a meaningful shift.

Still, with emissions continuing to rise and coal retaining a dominant share of electricity generation, the gap between current progress and what is required remains significant.

Looking ahead, the IEA’s findings are also overshadowed by geopolitical uncertainty, particularly the ongoing conflict in the Middle East and its impact on oil and gas supplies.

As Fatih Birol, Executive Director of the IEA, explains: "In a rapidly shifting landscape, countries that prioritise resilience and diversification will be best placed to manage volatility and deliver secure and affordable energy ahead."