An article at the European Institute for Climate & Energy (EIKE) website here takes a critical look at whether battery parks would be feasible to fully secure Germany’s weather-dependent power generation from wind and solar. 

Storing electric power to last Germany 10 days would require a 60 million-tonne battery. Image generated by Grok AI. 

Germany currently has a battery capacity of approximately 26 gigawatt-hours (GWh), the majority of which (approx. 20 GWh) consists of private home storage systems.

Only large-scale storage systems (approx. 4.3 GWh) are considered truly “grid-serving.” Currently, these could cover only about 5% of summer electricity demand for 1.5 hours.

The “Germany battery”: What would be required?

Energy expert Staffan Reveman presented a plausibility calculation for making Germany self-sufficient (without fossil fuel plants or imports). The results are sobering.

10 hour buffer

To achieve just 10 hours of buffer, a capacity of 600 GWh would be required – 24 times the current inventory and representing a material weight of approx. 3 million tonnes.

10 days of buffer

To bridge a ten-day “Dunkelflaute” (dark doldrums) in winter with a 50 GW load, 12,000 GWh would be needed. This is 470 times the current total capacity and 2,800 times the current large-scale storage. Such a battery would weigh 60 million tons. A modern factory (like CATL in Thuringia) would theoretically need 857 years to produce this amount.

Constant replacement

A central drawback is the limited durability of batteries (approx. 10–15 years). To operate a system of 12,000 GWh permanently, batteries would need to be replaced conbtinuusly. Reveman calculates that approximately 57 mega-factories would need to produce continuously just to maintain this inventory.

Astronomical cost

A simulation for the Traunstein district showed that self-sufficient supply via wind, solar, and batteries would increase wholesale electricity costs from 6 cents to 217 cents per kwh.

Moreover, a 240-hour battery (12,000 GWh) would require an area of approx. 600 square kilometers (roughly two-thirds the size of Berlin).

Conclusion

The EIKE author concludes that batteries alone cannot guarantee a secure power supply. Even under massive expansion scenarios for 2030, gaps remain (especially in winter) that would strictly require a flexible power plant reserve (e.g., gas-fired plants) or imports.

Furthermore, lack of grid stability (missing rotating mass) is cited as a significant technical hurdle.