Europe’s Solar Expansion Intensifies Price Volatility, Boosting the Case for Battery Storage

Europe’s rapid expansion of solar capacity is increasingly challenging the power market’s ability to absorb renewable generation. High solar output is often coinciding with moderate electricity demand, strong wind generation and limited grid flexibility, resulting in more frequent periods of oversupply.

As a result, low and negative electricity prices are becoming increasingly common during peak solar generation hours. At the same time, sharp price spikes are occurring more frequently during summer evenings, when flexible generation, including gas-fired power plants, must ramp up quickly as solar output declines.

According to S&P Global, negative-price hours across five major European electricity markets, including Great Britain, increased by around 2% in the first half of 2026 compared with the record levels seen during the same period in 2025. Across the whole of 2025, the number of negative-price hours was more than 13 times higher than in 2022.

Market conditions continue to vary significantly across Europe. France recorded the highest number of negative-price hours, partly due to high nuclear generation. In Germany, higher gas prices provided some support for electricity prices during the summer, while Italy recorded no negative-price hours due to its greater reliance on gas-fired generation.

Nevertheless, the broader trend of increasing price volatility is spreading across most European markets.

Batteries Gain Value as Price Spreads Widen

The widening gap between low and high electricity prices is strengthening the economic case for battery energy storage systems (BESS).

Data from Platts, part of S&P Global Energy, show that battery-accessible wholesale price spreads in Germany reached daily peaks of more than €650/MWh in the second quarter of 2026, while the average spread was close to €200/MWh. These levels exceeded those recorded in Spain and Great Britain.

In solar-heavy markets such as Spain, growing price volatility is strengthening the investment case for utility-scale battery storage while also reshaping the revenue outlook for market-exposed solar projects.

Around 10%–15% of Europe’s solar capacity is currently exposed to merchant market risk, while more than 61 GW is contracted through power purchase agreements (PPAs). In Germany, approximately 9% of installed solar capacity is directly exposed to market prices.

According to S&P Global, the challenge facing solar is not its technological or economic competitiveness, but the declining market value of unadjusted solar generation during peak production periods. Solar plants are increasingly generating electricity at times when the power system needs it least and when wholesale prices are at their lowest.

PPAs Evolve Toward More Structured Products

The changing market dynamics are also reshaping Europe’s PPA landscape.

Traditional “pay-as-produced” PPAs, under which buyers purchase electricity as it is generated, were designed for markets where renewable generation generally maintained a relatively high market value and generation-profile risks were easier to manage.

However, as solar penetration increases, this model exposes buyers to greater profile risk. Electricity may be delivered when renewable generation is highest, regardless of whether it matches consumption patterns or favorable market prices.

“The drop in contracting for independent solar projects shows that negative prices are becoming a structural issue in PPA design, rather than just a problem for the merchant market,” said Bruno Brunetti, Head of Renewable Revenue Streams at S&P Global Energy Horizons.

Independent solar PV accounted for more than 55% of PPA deals announced in Europe in 2025. Its share fell to around one-third in the first half of 2026, with less than 3 GW contracted.

According to Brunetti, corporate buyers continue to seek renewable electricity but are increasingly favoring contracts that address delivery timing, captured prices and exposure to negative-price periods.

Solar + Storage Becomes Increasingly Important

As electricity markets become more volatile, combining renewable generation with flexible technologies such as battery storage is becoming increasingly important.

The market is gradually moving away from simply buying or generating a specific volume of renewable electricity toward actively managing when electricity is generated, stored and delivered.

S&P Global expects the market to move toward models that better match electricity generation with demand on an hourly basis. Hourly certificates and other granular tracking mechanisms could become an important next step in corporate clean energy procurement, shifting the focus from annual renewable energy volumes toward matching renewable generation with actual consumption over time.

The development highlights a broader trend across Europe: as solar deployment accelerates, energy storage, flexible generation and more sophisticated PPA structures are becoming increasingly important to maintaining project revenues and grid stability.