Studies show that negative electricity prices decrease significantly once storage capacity reaches around 25 per cent of installed photovoltaic capacity. Where this figure has already been achieved, such as in the United Kingdom, negative electricity prices are unheard of. “Large-scale storage facilities can remedy the imbalance – and open up new investment opportunities“, comments Patrick Lemcke-Braselmann, Co-CEO of the aream Group.

Negative electricity prices reveal the limits of the energy transition: when the sun and wind supply more electricity than Germany consumes, energy becomes a loss-making business. In 2024, there were 459 hours with negative prices, which corresponds to 5.2 per cent of all hours in the year. In 2022, the share was still 0.8 per cent.

”However, negative prices are not a law of nature”, says Lemcke-Braselmann. The solution to the problem is more storage. ”They are an essential key to making the energy transition efficient, economical and stable”, explains Lemcke-Braselmann. This is because surplus electricity can be stored temporarily and fed back into the grid when needed. But there are huge gaps here: Germany currently has less than three percent large-scale battery storage capacity measured in terms of installed PV capacity – significantly less than other advanced markets, where storage shares of 20 to 30 percent have been achieved. And once storage capacity reaches around 25 per cent of installed photovoltaic capacity, negative electricity prices will largely be a thing of the past. To achieve this goal by 2030, Germany would need to install around 54 gigawatts of battery storage – more than twice as much as currently planned. Without expanding storage capacity, negative prices and a divergence between base load and solar power prices will continue to be a threat.

Conclusion: ”A lack of storage capacity means that surplus energy has to be sold at negative prices on the exchange”, says Lemcke-Braselmann. Grid stability suffers and the costs of interventions in the electricity grid – known as redispatch measures – amounted to around 2.7 billion euros last year. ”For Germany, this means that only with massive storage expansion and digitalisation of the system can green electricity be produced cost-effectively and used flexibly.”