German home battery owners can save state millions with ‘a maximum of six clicks’

More than 1.8 million home solar energy storage systems, with a cumulative capacity of 15 GWh have been installed in Germany, almost a third of them last year.

Researchers at Berlin University of Applied Sciences (HTW) want to harness that battery fleet to help the grid, and have launched a Your Power Storage Can Do More! campaign.

The researchers say many of those 1.8 million units could operate energy-consumption-forecast-based “intelligent charging” with just a few clicks, with the result that “The battery storage systems last longer, counteract bottlenecks in the power grid on sunny days and, on top of that, relieve the federal budget by tens of millions of euros annually.”

The researchers want to educate home battery owners on how to activate intelligent charging, “with a maximum of six clicks,” according to Johannes Weniger, initiator of the campaign.

In default mode, most batteries charge early in the morning, as soon as surplus solar power is generated by the panels connected to the energy storage unit. On cloudless, sunny days, such batteries will be fully charged by mid morning and will then feed surplus electricity into the grid, causing bottlenecks for electricity network operators.

To integrate more solar arrays into the grid, intelligent battery operation can delay the charging process, based on solar power forecasts, but HTW Berlin says many owners are unaware of the option.

Forecast-based charging also reduces downtime for highly-charged batteries, reducing “calendar-based” aging of the devices. The Berlin researchers said that can extend lithium-ion battery life at least two years.

Intelligent charging would see more solar electricity injected into the grid during morning hours, when demand and electricity prices are higher than at midday.

The researchers analyzed electricity prices in 2024 and found intelligent charging would have raised the average market value of solar electricity fed into the grid 28%, from €0.032 ($0.035)/kWh to €0.041/kWh.

Higher-value solar electricity would mean less pressure on the fund connected to Germany’s Renewable Energy Sources Act (EEG), which pays out “feed-in premiums” to home-solar owners to top up the difference between the value of their exported electricity and a fixed amount set by the government.

“If all home storage systems charge at midday, we could already relieve the federal budget by tens of millions [of euros],” said Volker Quaschning, professor of renewable energy systems at HTW Berlin. “We cannot afford to neglect this easily exploitable potential.”

Manufacturers

Seven manufacturers are already supporting HTW Berlin’s initiative: E3/DC, Fenecon, Kostal, RCT Power, SMA, Sonnen, and Tesvolt. Fenecon and RCT Power have delivered home solar energy storage systems with forecast-based charging options activated by default for years, according to HTW Berlin. The other manufacturers listed above have demonstrated, based on operating data from real systems, they advertise forecast-based charging strategies and offer them to their customers.

From pv magazine Deutschland.