Car batteries and home storage to help balance Germany’s grids

Germany will allow batteries installed in private homes, electric cars or those run by businesses to both take electricity from the grid and feed it back. The country’s grid agency BNetzA adopted a new regulation, dubbed MiSpeL, to better integrate batteries into the electricity market, by simplifying rules for buying electricity when it is plentiful and cheap, and selling it back when generation is low and prices are high. But industry players have said the changes don't go far enough.

“This will allow millions of committed households to become active shapers of the energy transition,” said BNetzA head Klaus Müller. The regulation “offers a pragmatic and digital solution that provides maximum freedom for innovation whilst establishing clear safeguards against misuse,” BNetzA wrote in a press release.

Previously, battery storage systems needed a strict separation of the electricity they stored. Only batteries with green electricity, generated solely through renewables, were eligible for subsidies. Storage systems drawing electricity from the grid, where energy sources also include coal and gas, were not. The BNetzA now changed regulation so that, while renewable electricity storage subsidies remain in place, there are also lower levies and grid fees for batteries storing power from the grid. 

Many electric vehicles (EVs) can already technically feed electricity back into the grid, but taxes and grid fees have so far meant that bidirectional charging does not make financial sense for car owners. Bidirectional charging enables the batteries inside EVs to function as standard storage systems, withdrawing electricity from the grid when there is plenty available, or supplying it back if the car is not in use – bringing flexibility into the power system and earning owners money.

A consortium of major car manufacturers, along with electricity companies said last week that the new rules were still too complicated because they involved significant technical, economic and operational hurdles that jeopardised market rollout. Key points of contention were rules on state support and smart meter requirements.

Flexibility is key in an electricity system that relies on intermittent renewable energy sources. Storage, flexible demand management and flexible back-up power plants will all play an important role in ensuring security of supply as well as optimising the electricity system's operation and costs.