On Tuesday afternoon it happened again. Electricity cost nothing for a few hours in the Netherlands. Anyone who purchased electricity received money: half a cent per kilowatt hour (kWh). This was because the amount of power that wind farms generated during the first autumn storm caused a surplus. The negative prices on the energy exchanges help to eliminate the surplus on the power grid – you can also temporarily switch off solar parks or wind turbine fields or quickly switch on other heavy consumers.
Most consumers do not notice this balancing act and price fluctuations: more than 95 percent of households pay a fixed or almost fixed rate. But anyone who has a dynamic energy contract and their own battery can participate in the trade themselves. You store a few kWh when electricity is cheap or free and supply it back to the network during the expensive peak hours in the evening. On paper, such a battery seems like a great investment. You can earn money with it, it helps to remove the peaks from the overloaded network and it buffers your own solar energy. But is it also worth it?
A home battery is not a cheap purchase: count on 700 to 1,000 euros per kilowatt hour, including installation. Individual batteries cost less, but often require additional equipment and an experienced technician. An average household needs about 5 kWh of storage – batteries that are too large are not profitable at all. Charged, a home battery supplier from the Betuwe, supplies storage from 5 kWh. At competitor Soley it starts at 3.5 kWh. A battery wears out and lasts five to six thousand charging cycles. After ten years, approximately 80 percent storage capacity remains.
All the solar panels and wind turbines increase the number of hours with negative electricity prices; more than this year 230 hours. That’s not a fat guy. Take last Tuesday. The difference between the negative price and the highest price was 15 cents. With a 5 kWh battery you earned 75 cents. On some days the profit is a few euros, but earning back your battery is difficult, also because there is a loss when storing and returning power.
And how useful is that other scenario, using the battery to temporarily store your own solar power? At the moment, the netting scheme is the best battery: what you, as a private solar panel owner, supply in electricity in the summer, you can deduct from your use in the winter at the same rate. But that rule will be phased out from 2025, in steps until 2031.
The home battery is not yet profitable in the Netherlands, says Sanne de Boer, energy transition analyst at RaboResearch. She uses her own home in Utrecht as an example. A 5 kWh home battery is not large enough to store the yield of six panels – in the summer they supply 10 kWh. Her daily consumption of 2 kWh is again insufficient to drain the full battery. Well, you can partially charge an electric car with the remaining electricity, but not everyone has that option. Another energy guzzler, the heat pump, is not necessary in the summer.
Lucas van Cappellen from research agency CE Delft investigated the efficiency of the home battery. He assumed a combination of trading in electricity himself and buffering solar energy, and arrived at a payback period of fifteen years.
It may be more convenient to use the batteries in electric cars as a buffer: by 2030 there will hopefully be enough cars on the market that can charge smartly and ‘bidirectionally’ and also return electricity.
Batteries without wheels are better suited for large-scale consumption, for example as a buffer at large solar parks. They now have to switch off if they supply too high peaks to the grid. To solve the imbalance in the power grid, you can’t make a dent in a pack of butter with your own home battery. At most, if you bundle different batteries into one virtual power plant, you can make a fist.
Smart meter, stupid use
The smart grid, the smart and interactive energy grid, is getting off to a slow start in the Netherlands. So much is possible, but little is happening. The power grid Crashes and despite the smart meter in almost every meter cupboard, electricity use remains stupid in most Dutch households. This is due to outdated rules and outdated behavior. We generate too much power with solar panels that often face south and thus increase peak loads. We use a lot of electricity at times when it is expensive – because it makes no difference to the bill if you pay a fixed rate.
The sky-high energy prices of 2021 and 2022 proved that consumption patterns change quickly, if necessary. Rules also help: in Belgium, for example, there is no longer any netting and this will be the case in 2022 more than 52,000 home batteries registered thanks to a subsidy scheme (now stopped). Belgian households have an extra incentive to dampen their consumption peak: since the introduction of the capacity rate you pay extra if you use a lot of electricity in a short time. If such a grid tariff also applied in the Netherlands, it would become more attractive to support yourself as much as possible, for example with a home battery. In Germany, the government is helping and from next week homeowners will receive up to ten thousand subsidy on the combination of solar panels, home battery and car charger.
Dynamic prices also help reduce pressure on the network, says Remko ten Barge of energy company NieuweStroom. He looks with awe at Norway, where three-quarters of consumers move with the dynamic energy prices. According to him, this has removed 10 percent of the peak load on the power grid.
In the Netherlands, the home battery is still a toy for early adopters and sustainable nerds. Roeland Nagel from battery supplier Charged sold 2,200 ‘Sessy’s’, of which 1,000 have been installed. His customers do it, he thinks, mainly to feel less dependent. The payback has been quite good over the past two years, but that is no guarantee for the future.
I understand the battery jitters. My father would certainly have bought such a home battery. In the 1990s he was the first in the village to install solar panels on the roof – the neighborhood was concerned whether he had a leak or joke about the mind. Until four years ago, every kWh generated was recorded with a black pen on green graph paper. Solar power was a way for him to be autonomous, less dependent on The System. That’s what happens when you grow up on a farm; you prefer to shell your own beans.
Somewhere up there, he now counts the solar panels on more than two million Dutch roofs and is satisfied that anyone can become an electricity farmer. Perhaps a home battery is of no use at the moment. But as every farmer knows: you must first sow before you can harvest.