If you want to install a wallbox at home to charge your electric car, you have had to register it with the network operator for several years. For charging capacities of more than 11 kilowatts, a permit is required to prevent overloading of local lines and transformers. In practice, however, it is not so easy for municipal utilities and private network companies to keep track. "Not every driver registers the new wallbox. Some member companies report a dark figure of up to 50 percent that go online without a connection permit," said a spokesman for the Association of Municipal Companies (VKU). The association does not see an immediate security risk as a result, as there is usually still enough free capacity available in the short term.

Helmut Bünder

Business correspondent in Düsseldorf.

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The emphasis, however, is on the short term. Because one thing leads to another. In addition to charging electricity for 15 million electric cars, the lines are expected to be able to cope with six million heat pumps by 2030, mostly combined with photovoltaics on the roof and often an electricity storage system in the basement. At the same time, the distribution grid forms the busbar for green electricity. According to VKU, around 95 percent of all renewable energy plants feed their electricity into the distribution grid, and their output is expected to more than double in the coming years. "The distribution grids are not designed for this development," states the Stadtwerke Association.

According to the grid operators and the Federal Network Agency, large-scale power outages are not expected for the time being. The concern is more that the power supply for individual streets or districts will have to be switched off if the load flow becomes too large at peak times. These are usually the evening hours, when cars are charged after work and household appliances are switched on.

"The risk increases"

"The risk increases if even more heat pumps and wallboxes are now installed on a large scale," warns the VKU. One is relieved that the traffic light no longer relies exclusively on heat pumps. Running gas heating systems with hydrogen or biomethane can help relieve and stabilize the distribution grid," a spokesman said. However, this still had to be designed "practicable" in the law.

For the time being, improvisation is underway to keep the distribution grid stable despite the growing loads. The Federal Network Agency is working on a safety mechanism that will enable grid operators to temporarily reduce the power supply of wallboxes and heat pumps. Electric cars could then only be charged with a minimum output of 3.7 kilowatts. At the beginning of 2024, the highly controversial regulation is to come into force. The car industry, heat pump manufacturers and the Federation of German Consumer Organisations are up in arms against this: The curtailment "is not reasonable," according to a joint position paper.

On the other hand, Eon and many other network operators consider the interventions to be inevitable, because the network expansion – "despite the best possible planning" – does not catch up with demand fast enough. This is why control options are needed to enable all customers to quickly switch to heat pumps and electric cars without endangering local grid stability.

Network Agency: Interventions only in exceptional cases

So far, there is only one key issues paper. By the summer, the network Agency wants to present a formulated draft. "I am confident that the local power grids will soon be able to enable the heat transition everywhere. According to our regulatory proposal, everyone can be sure that their heat pump will be connected," said Network Agency President Klaus Müller of the F.A.Z. The Network Agency assumes that interventions will only be necessary in exceptional cases.