Fraunhofer ISE has launched an online price simulator tool to simulate the impact of battery storage on electricity prices
The simulator uses German actual day-ahead market bids to model different battery deployment scenarios
The analysis highlights the potential of battery storage to influence solar's market value
Using Germany’s 2025 electricity market data, Fraunhofer ISE estimates that adding 20 GW of battery storage capacity with a two-hour duration could have increased solar’s market value by around 35% and reduced daily electricity price spreads by 60%.
It makes these estimates using its newly launched online price simulator that helps assess the impact of battery storage on wholesale electricity prices, based on actual buy and sell bids from the day-ahead electricity market, aggregated by European power exchange EPEX SPOT.
The Fraunhofer ISE price simulator allows users to model how different battery power capacities and storage durations could influence electricity prices.
The simulator adds a selectable battery fleet to the market data and calculates how the additional buying and selling activity would affect electricity prices. Users can adjust battery power capacity from 0 to 20 GW, storage duration from two to six hours, and various market scenarios. In the simulation, the batteries operate at an efficiency of 86%. It factors in their aging costs/MWh stored.
Results are available at 15-minute intervals and include battery charging and discharging patterns, state of charge, solar and wind generation, and electricity consumption. The tool is freely accessible and updated daily with the latest trading results, says the German institute.
In its analysis of 2025 market data, Fraunhofer ISE modeled a scenario with 20 GW of battery storage and a two-hour duration, equivalent to 40 GWh of energy capacity. It found that the average daily price spread between the most expensive and cheapest 15-minute periods fell from €130/MWh to €53/MWh, a reduction of 60%. The number of hours with electricity prices above €200/MWh declined from 169 to 20, while negative-price hours dropped from 575 to 271.
The simulation also showed that battery storage could raise the market value of solar power by 35% from €45.08/MWh to €61.02/MWh. On January 20, 2025, the year’s most expensive day, the modeled battery fleet would have reduced the evening price peak from €583/MWh to €221/MWh. On May 11, 2025, when prices were lowest last year, batteries would have absorbed midday electricity and raised prices from minus €250/MWh to minus €20/MWh.
Fraunhofer ISE said the simulator uses historical market bids to provide a “what-if” analysis rather than a forecast. However, it does not include potential revenues from intraday trading, system services or balancing energy, or the benefits of reducing grid congestion.
Leonhard Gandhi, Project Manager for Energy-Charts at Fraunhofer ISE, said the tool is intended to provide a common data basis for discussions about battery storage and electricity prices. “Storage systems smooth out prices, but they don’t generate electricity. The simulator illustrates both of these points very clearly and thus also shows that we need to consider storage and reliable power generation together,” added Gandhi.
Fraunhofer ISE has made the simulator publicly available on its Energy-Charts.info platform.
Recently, a Fraunhofer IEE study identified 150 GW of additional PV potential in Germany with the addition of BESS across 1,313 substations. This would require around 60 GW/240 GWh of storage (see Germany: Battery Storage Can Unlock Additional 150 GW Solar PV).
