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Charging station of an electric car

Photo: Marijan Murat / dpa

More and more electric cars and heat pumps are being sold in Germany. If both need electricity at the same time – for example, on cold winter evenings when people want to turn up their heating and charge their electric cars – this can become a problem for distribution grids, specifically for the low-voltage lines on the last few kilometres to the houses. How do you deal with it when electricity becomes scarce?

The Federal Network Agency has now drawn up rules for such cases: In future, grid operators will be allowed to temporarily restrict the purchase of electricity from new controllable heat pumps or charging stations if there is a risk of overloading the power grid. However, "a minimum service must always be available," the Federal Network Agency announced.

The Federal Network Agency's approach is primarily to allow grid operators to temporarily restrict the purchase of electricity from new charging stations and heat pumps if this is necessary to avoid overloading the local distribution grid. In this case, therefore, it is not about the major electricity highways from north to south.

50 kilometres instead of a full charge

What does this mean in concrete terms? The distribution system operators are allowed to reduce the consumption of the affected households to up to 4.2 kilowatts for the duration of the overload. "This means that heat pumps can continue to operate and electric cars can generally be recharged for a distance of 50 kilometres in two hours." Regular household electricity would not be affected, the authority said.

The balancing act for the authority: On the one hand, the requirements should make a difference; on the other hand, heat pumps, among other things, should not be switched off for hours. In the run-up to the event, there was talk of a "mandatory exception" or "ultima ratio". Ideally, consumers should hardly notice when their electricity consumption is throttled; a basic service should be secure.

In return, the operators of the controllable devices, such as households, receive a discount. Either as an annual lump sum for the grid fee or as a 60 percent reduction in the electricity energy price for the respective devices. From 2025, those who opt for the flat rate will also be able to opt for a time-varying network fee. Consumers then pay less grid fee when purchasing electricity during periods of low grid utilization. In addition, network operators are no longer allowed to refuse to connect controllable consumption devices with reference to possible bottlenecks.

The Federal Network Agency assumes that interventions by network operators only have to take place in exceptional cases, and the loss of comfort is also limited. "Complete shutdowns," for example, are no longer permissible, it said. Network operators must also publish such control interventions on the Internet. This means that it is also comprehensible to the general public if problems arise in individual network areas and the network operator needs to better equip its network.

Rules from January

The new rules will apply from January. In the case of existing plants for which there is already an agreement on control by the grid operator, there are long-standing transitional arrangements. Existing installations without such an agreement remain permanently exempt, but can participate voluntarily. Night storage heaters are not to be covered by the new rules in the long term.

In the past, the Federal Network Agency has repeatedly warned of bottlenecks: Operators nationwide are investing billions in expanding local networks. Nevertheless, it happens that companies only connect new charging stations after a waiting period when they can no longer keep up with the expansion on site. The majority of low-voltage grids in Germany are not yet equipped for a rapid ramp-up of electric cars and heat pumps, the Federal Network Agency explained.