European Solar Capture Factors Collapse as April Oversupply Triggers Wave of Negative Prices

Europe’s power markets came under acute pressure during April 2026 as strong solar output collided with weak shoulder-month demand, driving a collapse in capture factors, and setting the stage for record negative pricing episodes seen in early May.

A comparison across five European core markets shows a clear year-on-year deterioration: capture factors declined materially across most markets. Additionally, the proportion of solar production under negative price hours increased, in some cases sharply. The shift reflects a combination of higher solar installed capacity, and consistently weak demand during a shoulder month. Despite broader volatility in commodity markets linked to the Iran conflict during the period, the data suggests solar capture factors remained primarily driven by structural oversupply dynamics within European power markets rather than by fuel or geopolitical price movements.

France – Solar capture collapse accelerates pressure for co-located solar reform

France stands out for the scale and speed of deterioration. Solar capture factors fell to around 0.10 in April 2026, down from roughly 0.42 in April 2025, a 75% drop year-on-year. At the same time, negative price hours rose to 139 hours from 90, while demand remained seasonally weak due to mild temperatures and holiday periods, nuclear availability improved, with generation rising to around 29 TWh in April 2026 from 27 TWh the previous year. This higher level of nuclear generation increased the amount of low-marginal-cost baseload power already present on the system during solar peak hours, reducing the room for additional midday solar output, which had risen to 3.4 TWh during the month, compared with 2.8 TWh in 2025. With neighboring markets also experiencing similar solar surpluses, export opportunities were limited, leading to more frequent domestic oversupply conditions and deeper price collapses during peak solar production hours. In fact, France experienced one of the sharpest deteriorations in the proportion of solar generation produced during negative price events jumping from 29.2% in April 2025 to 45.1% in April 2026.

These market conditions support France’s proposed reform of large-scale solar CfDs. The Energy regulator CRE has proposed shifting support from a solar capture-based reference price to a baseload index while also reducing compensation during negative price periods. Under the current structure, the state effectively absorbs much of the cannibalization risk faced by standalone solar. However, April 2026 illustrates how rapidly that exposure is increasing as capture factors collapse and negative pricing events become both more frequent and more persistent. The proposed redesign transfers a larger share of this risk back to generators while explicitly favoring co-located PV and BESS. By allowing batteries to charge during negative price periods without losing support, and by extending compensation to energy shifted into higher-priced hours, the reform effectively rewards flexibility rather than pure generation volume.

Germany – Longer negative price events expose growing merchant risk for solar

Germany shows a similar but more structurally embedded trend. Capture factors fell from around 0.40 in April 2025 to approximately 0.26 in April 2026, a decline of one third, while negative price hours increased from 75 to 123, a rise of 65%. The country saw the share of solar generation produced during negative price periods rise from 32.6% in April 2025 to 46.8% in April 2026.

A key structural element in Germany is the legacy EEG subsidy framework. Older renewable assets continue to receive support during negative price periods of up to six consecutive hours, reducing incentives to curtail generation during oversupply events. This has historically contributed to longer and deeper negative pricing episodes. While newer EEG rounds impose stricter rules, the legacy fleet still accounts for a significant share of installed capacity.

EEX data shows that negative pricing events are becoming not only more frequent but materially longer in duration, an important trend in the context of the country’s EEG subsidy rules. In April 2025, Germany recorded 13 events of negative prices lasting longer than one hour, of which only two extended beyond the six-hour threshold (after which many older EEG-supported assets lose subsidy eligibility). By April 2026, the number of events lasting more than one hour had risen to 22, with eight lasting longer than six consecutive hours. The longest continuous negative pricing period also increased sharply, from seven hours in April 2025 to 17 hours in April 2026, indicating that oversupply conditions are becoming increasingly persistent.

Combined with continued solar capacity additions and limited short-term demand flexibility, this results in pronounced midday price suppression, particularly during high solar irradiation periods in spring.

Italy – Regional grid constraints push southern markets toward persistent zero prices

Italy presents a distinct case due to its market design, which does not currently allow negative prices in the Day-ahead market due to structural market features, including ancillary service mechanisms that effectively maintain a price floor and reduce incentives for participants to bid below zero. Instead, oversupply manifests through an increasing number of zero-price hours. Capture factors fell from around 0.75 in April 2025 to approximately 0.71 in April 2026, marking the second lowest level on record, with only May 2025 lower. While this decline is less pronounced than in other markets, it is notable given Italy’s still relatively lower solar penetration compared to Spain or Germany. The effect is highly regionalized. April 2026 saw the emergence of zero-price hours across central-southern zones, with Calabria and Sicily also recording repeated occurrences, whereas April 2025 showed almost no such events. Northern Italy remained largely unaffected. This highlights a structural divide: southern regions, with higher solar exposure and weaker interconnection, are increasingly facing local oversupply, while limited north-south transmission capacity constrains system balancing.

Spain – Winter oversupply signals that solar cannibalization is no longer seasonal

Spain’s data highlights that capture risk is no longer confined to spring and summer. Capture factors in Spain continued earlier trends of deterioration by falling slightly in April, from around 0.30 to 0.28 year-on-year, but more striking is the winter dynamic. In February 2026, capture factors dropped sharply to around 0.18, compared to roughly 0.71 in February 2025, driven in large part by exceptionally strong hydro output displacing most other types of generation. At the same time, negative price hours surged to 148 in February 2026 from zero the year before, indicating that oversupply conditions are now emerging even in winter months. In April, negative pricing increased from 117 to 138 hours, with the share of solar production occurring during negative price periods rising from 35.2% to 41.2% year-on-year. Spain’s rapidly expanding solar fleet, combined with limited storage and constrained export capacity during periods of regional oversupply, is increasingly exposing solar assets to both seasonal and structural price pressure.

Poland – Early signs of solar oversupply emerge in a traditionally thermal market

Poland is also showing increasingly visible signs of solar cannibalisation. Capture factors declined from around 0.54 in April 2025 to approximately 0.40 in April 2026, a drop of roughly 25%, while negative price hours increased from 75 to 87. Poland also showed a comparatively smaller increase in the share of solar output generated during negative price periods, rising from 27.1% to 28.5% year-on-year in April. This shows that while oversupply pressures are emerging, they remain less severe than in Western European markets. While these shifts are less extreme than in France or Germany, they indicate that solar-driven price pressure is becoming increasingly material in Poland as renewable penetration rises. Poland’s coal-heavy generation mix and comparatively lower solar buildout have so far helped maintain higher capture factors than in more saturated Western European markets. However, increasing solar deployment and stronger integration with neighbouring markets suggest that similar pressures could intensify over time, particularly during low-demand periods.

Widening solar-driven spreads strengthen the investment case for BESS across Europe

Across all markets, both Day-ahead and intraday Top-Bottom (TB) spreads available to BESS widened materially year-on-year. France and Germany recorded some of the sharpest increases, with April Day-ahead spreads expanding by roughly 20%. Germany in particular saw intraday volatility intensify further, highlighting the growing challenge of balancing large volumes of solar generation in real time. Spain also showed a clear widening trend, though from a lower base, while Poland remained by far the most volatile market overall, with spreads increasing by around 15% year-on-year in April. Italy again displayed strong regional divergence. While spreads increased across the country, southern zones consistently recorded significantly higher volatility than the north, with April day-ahead spreads in southern Italy rising by one third year-on-year, compared to around 20% in the north. The broader trend across all markets is clear: midday oversupply is driving increasingly sharp price swings, increasing the value of flexible BESS assets.

Taken together, the April 2026 data suggests European solar markets may be entering a new phase where periods of severe midday oversupply are no longer isolated events but recurring structural conditions, particularly in shoulder months. Early May has already reinforced this trend, with several markets recording record or near-record negative pricing events and further deterioration in solar capture economics. In Germany and France in particular, prolonged negative-price periods are becoming increasingly common, raising the prospect that 2026 could set new lows for solar capture factors across parts of Europe if current buildout trends continue.

The broader implication is that solar deployment is now advancing faster than system flexibility. While storage pipelines across Europe are expanding rapidly, current BESS penetration remains too limited to materially compress Day-ahead spreads or absorb large-scale midday surpluses at the system level. Until BESS deployment, demand-side flexibility and grid expansion scale more meaningfully, markets are likely to continue experiencing deeper midday price collapses, wider spreads and increasingly volatile capture outcomes during high-generation months.

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