A different kind of volatility: Battery revenues remain strong in May 2026

Few consecutive months have illustrated the changing nature of battery value as clearly as April and May 2026.

April was characterized by strong renewable generation, prolonged negative prices, and widespread solar oversupply. In May, weak wind conditions pushed renewable output lower, fossil generation higher, and average wholesale prices back towards levels last seen during the winter.

At first glance, these conditions would seem less favorable for battery trading. Negative-price events became less frequent, and the solar-driven arbitrage opportunities that dominated April softened. Yet battery revenues remained remarkably stable.

The reason is simple: while volatility changed shape, it did not disappear. For battery operators, this meant, the source of value shifted. The overall opportunity remained.

May in numbers

The resilience of battery revenues becomes evident when looking at the earnings potential of a representative 10 MW/20 MWh stand-alone battery in Germany.

Among wholesale markets, continuous intraday trading once again delivered the strongest performance at €15,400 ($17,560)/MW per month. Day-ahead trading followed at €11,400/MW, while intraday auctions reached €11,000/MW. Compared with April, wholesale revenues softened modestly as average price levels increased but extreme spread opportunities became less frequent.

Ancillary services moved in the opposite direction. FCR rose to €14,000/MW per month, while aFRR Negative increased significantly to €17,100/MW per month, reflecting tighter system conditions and a growing need for downward flexibility. aFRR Positive reached €7,000/MW, while a stacked aFRR strategy averaged €12,000/MW. Activation revenues in the aFRR energy market continued to increase as well, reaching €2,600/MW.

As usual, the strongest results emerged from combining markets. A stacked wholesale strategy combining intraday auctions and continuous intraday trading generated €19,000/MW per month. Meanwhile, suena energy’s Energy Trading Autopilot achieved €24,500/MW per month through dynamic cross-market optimization, surpassing April’s result of €23,600/MW per month despite a markedly different market environment. The Autopilot also continued to outperform every other market strategy by between 28% and more than 240%, underlining the value of coordinated participation across wholesale and balancing markets.

Scarce flexibility

May confirmed once again that German battery energy storage system (BESS) revenues are driven by volatility rather than price levels – only this time, the volatility came from the opposite direction.

The month began with a familiar reminder of seasonal market dynamics. On May 1, strong solar generation coincided with holiday-related low demand, pushing day-ahead prices to the technical minimum of -€499.99/MWh and sending individual intraday auction products below -€850/MWh.

Yet these episodes became far less frequent over the remainder of the month. After recording 123 negative-price hours in April, Germany saw “just” 77 such hours in May 2026 – still among the highest May values on record, but significantly below the 129 hours observed last year.

Instead, market participants increasingly faced pronounced morning and evening ramp periods. As solar generation entered and exited the system, conventional generation struggled to adjust quickly enough, creating steeper price gradients across the day. These increasingly visible “duck curve” dynamics translated directly into arbitrage opportunities for flexible assets.

At the same time, ancillary service markets reflected a system operating with less renewable surplus and fewer flexibility reserves. The strong increase in aFRR Negative prices and activation volumes suggests that batteries were increasingly being called upon to absorb imbalances and support system stability.

Perhaps the most important lesson from May is that battery value is becoming increasingly independent of any single market condition. April rewarded flexibility during periods of renewable abundance. May rewarded flexibility during periods of relative scarcity.

For batteries, both situations create value. Whether the system is managing excess renewable generation or responding to tighter market conditions, flexibility remains the scarce commodity.

Value sources

The coming summer months are likely to bring further periods of elevated volatility across both wholesale and balancing markets. Solar generation will continue to increase, ensuring that periods of midday oversupply remain a structural feature of the market. Yet while negative-price events continue to occur with increasing frequency – 2026 is already on track to become another record year – market opportunities are unlikely to be defined by a single price pattern alone.

What matters is not the specific source of volatility, but the flexibility required to manage it. For battery storage operators, this reinforces the importance of dynamic market participation.

May demonstrated exactly that. The market regime changed almost completely. Battery revenues did not.

And that may be the clearest signal yet that in an increasingly renewable power system, flexibility is becoming less dependent on specific market conditions – and more essential under all of them.