Zero Prices Are Creating a Storage Opportunity in Spain’s Power Market

Spain’s electricity market is entering a decisive transition phase. Rapid renewable deployment, increasingly frequent zero and negative prices, and widening intraday price spreads are fundamentally reshaping power market economics. According to Spain’s power market operator, OMIE, these shifts are no longer theoretical signals—they represent a clear investment window for energy storage.

Speaking at the APPA Renovables Congress, Carmen Becerril Martínez, President of OMIE, outlined how current price dynamics are strengthening the business case for battery energy storage systems (BESS) and other flexibility assets.

Hourly Spreads Are Expanding—And That Matters

One of the most critical indicators for storage economics is the hourly price spread. OMIE data shows that the difference between low-price and high-price hours in Spain has increased by nearly 25% between 2024 and 2025.

This widening spread directly improves arbitrage opportunities for storage, allowing batteries to charge during low or negative price periods and discharge during high-value evening peaks.

“The hourly spread has increased by almost 25% between 2024 and 2025. This is a very encouraging signal for the future development of energy storage,” Becerril said.

For investors and developers, this marks a shift from speculative storage economics to observable, data-backed revenue potential.

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A Steeper Duck Curve Is Redefining Price Formation

Spain’s price structure is no longer following the traditional peak–off-peak model. Massive renewable additions—around 7 GW of new solar PV and 1.3 GW of wind year-on-year—have structurally altered supply patterns.

Midday solar generation is pushing prices sharply downward, while evening demand still relies on dispatchable capacity. According to OMIE:

• Midday prices are now ~40% below the daily average

• Evening peak prices can reach 75% above the daily average

This deepening duck curve creates pressure for merchant solar projects but simultaneously amplifies the value of flexibility, especially short- and mid-duration storage.

Quarter-Hourly Trading Increases Precision for Flexible Assets

Spain has introduced quarter-hourly trading, one of the most significant market design changes in recent years. Since March 2025, quarter-hourly products have been active in the intraday market, and from October they have been extended to the day-ahead market.

This shift increases daily scheduling intervals from 24 to 96, allowing batteries, demand response, and hybrid plants to react more precisely to real-time system conditions.

While traded volumes have not multiplied overnight, OMIE notes a gradual and orderly adoption, with renewables and flexible assets expected to be the primary beneficiaries over time.

Negative Prices Are No Longer Rare Events

Spain recorded its first negative day-ahead price in April 2024. Since then, negative and zero prices have become a recurring feature, particularly during spring and early summer.

Key figures underline the scale of the issue:

• Lowest recorded price in May 2025: –€15/MWh

• Zero or negative prices accounted for nearly 10% of all traded hours in both 2024 and 2025

These price events are no longer anomalies—they are structural outcomes of renewable oversupply during low-demand periods.

Curtailment Is Rising—Without Grid Constraints

Economic curtailment is accelerating, especially for solar and wind assets:

• 21% of solar PV energy offered in May failed to clear the market, even with bids below €5/MWh

• Wind curtailment reached around 20% in the same period

Crucially, these curtailments were not caused by grid bottlenecks, but by insufficient demand during high-generation hours. This further strengthens the case for co-located or standalone storage to absorb excess generation and stabilize revenues.

Capture Prices Are Diverging by Technology

Technology-specific capture prices are now diverging significantly:

• Wind: €62/MWh

• Solar PV: €34/MWh

For unsubsidized and merchant solar projects—especially those without long-term PPAs—this gap exposes revenue volatility and downside risk. Storage, hybridization, and demand-side electrification are increasingly becoming risk-management tools, not just optimization add-ons.

Demand Growth Is Lagging Supply Expansion

Electricity demand remains the missing piece. While Spain saw 3% demand growth in 2024, the rolling 12-month growth rate has slowed to around 2.1%.

Without accelerated electrification—EVs, heat pumps, industrial electrification—generation growth will continue to outpace consumption, reinforcing price compression during solar hours.

Forward markets reflect this reality. Futures for Q2 2026 are priced at €28–29/MWh for April and May, before recovering toward €58/MWh later in the year.

Storage Moves to the Center of Spain’s Energy Strategy

Taken together, these trends position energy storage as a core system asset, not a niche technology. Batteries are increasingly essential for:

• Capturing value from negative prices

• Reducing renewable curtailment

• Stabilizing merchant revenues

• Supporting grid reliability in high-RES systems

As Becerril summarized:

“If you are looking for a place to invest, Spain is probably not a bad option compared with other European markets.”

Spain’s market signals are now aligning—price volatility, policy direction, and technology readiness are converging to create one of Europe’s most compelling storage investment environments.

With events such as Future Energy Summit Iberia – Renewables & Storage 2026 bringing policymakers, utilities, IPPs, and storage developers together, Spain’s role as a flexibility and storage hotspot is becoming increasingly clear.

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