Background: Your electric car as a home battery?

Edited by Marijn Ceulemans, Rob Coenraads and Marco Mekenkamp

For those who have solar panels on the roof, it seems like a logical choice: storing and using excess energy when the sun is not shining. A home battery is in fact a large battery that is linked to your solar panels and the electricity grid. The battery stores the excess energy that your solar panels produce on sunny days. That stored electricity can be used later, for example in the evening or on cloudy days when you supply solar panels less or no energy. With a home battery you can therefore immediately use part of your self -generated energy and you have to be less dependent on the electricity grid. Popular brands such as Tesla with their Powerwall, LG Chem and BYD have invested heavily in this technology in recent years. In the Benelux, companies such as Eneco, Ilumen and Battery Supplies offer solutions that range from small -scale systems with a storage capacity of a few kilowatt hours, to large -scale batteries for larger households or companies. The use of home batteries offers a lot of benefits in theory. They make it possible to lower energy costs and give you more autonomy about your energy consumption. In addition, you contribute to a more sustainable electricity grid, because you are less dependent on power plants on fossil fuels.

Yet there must be a reason why the home battery still has a long way to take until it becomes established. It starts with the initial purchase costs, which are still high. A ‘standard’ battery quickly costs between four and ten thousand euros, depending on the capacity. Also because there are no purchase subsidies, the payback time is considerable. It depends on the amount of energy that you generate yourself, your consumption pattern and the legislation, which has undergone many changes in recent years. Moreover, a home battery takes on physical space and must be installed professionally.

The solution: electric car?

The electric car (EV) as a home battery offers an innovative solution that uses the same principles as a traditional home battery, but with a mobile twist. Thanks to bidirectional drawers you can not only store energy in your car, but also return it to your home. This makes it possible to give your car (which often stands still) a dual function: means of transport and mobile battery. And there is another important advantage: unlike most home batteries, electric cars often have a much larger battery capacity. A Tesla Model 3, for example, has a 60 kWh battery, while the Hyundai Ioniq 5 even offers a capacity of 77.4 kWh. For comparison: the Tesla Powerwall, a popular home battery, has a maximum capacity of 13.5 kWh. This means that an electric car is theoretically able to provide an average household with power, depending on the consumption. If you do drive electrically or want to drive, you could therefore save considerably on costs by not purchasing home battery. In addition, the larger storage capacity makes it possible to save more energy and use it flexibly. This can be particularly affordable during peak hours when the electricity prices are higher. The fact that you can also ‘take’ the energy, for example for use at a different location, adds a unique mobility factor that home batteries miss.

Smappee provides charging solutions that the energy consumption of your charging station keep an eye on at home and that of your entire home

Yet it is not all rose scent and moonshine. An important disadvantage is that your car must be available to function as a home battery. If you are on the road, the car can of course not supply energy to your home. In addition, frequent loading and discharging can influence the battery of your car battery, which can eventually entail higher maintenance costs. Bidirectional loading is also not yet standard functionality with all electric cars and requires special charging points and smart software, which makes things more complex (and possibly more expensive).

The practice: who offers what?

Although the technology around the concept of the electric car as a home battery, or Vehicle-to-home (V2H), promising, there are few car brands and energy suppliers that support them widely. Nissan was one of the first brands to introduce this technology with the LEAF, a popular electric car that has been supporting bidirectional loading for years. Hyundai and Kia have also launched models that are suitable for V2H applications. Tesla, market leader in electric cars, currently only offers one -way drawers, but CEO Elon Musk has indicated that bidirectional loading will be possible in the future. In the Benelux, companies such as Enervalis and Smappee are active in the field of smart energy solutions, including V2H. They often work together with car manufacturers, charging station producers and energy suppliers to further develop technology.

For example, Smappee has a smart energy management system that not only monitors the energy consumption of your charging station at home, but also that of your entire house. This keeps the consumption between the two in balance. With them Dynamic Load Balancing Avoid your power outages while at the same time loading your car, cooking, ironing or baking.

However, the range of ready-made systems is generally still limited and the installation often requires customization. Unfortunately, this will be a threshold for consumers who are looking for simple and affordable solutions for a while.

With the home battery Nexus from Zonneplan you can also earn money

EV or home battery?

The choice between a home battery and an electric car as a home battery depends strongly on your personal situation and needs. Do you already have an electric car and do you want to get the most out of your investment? Then V2H can be a logical next step. The extra costs are relatively limited if you already need a charging station and have your solar panels. Moreover, with a larger battery capacity you can build more flexibility in your energy management. On the other hand: if you often drive long distances and you need your car during the day, a fixed home battery may be more reliable. This is always available and depending on the capacity it can be sufficient to continuously provide your home with power.

Energy regulations also play an important role. In the Netherlands we still have the netting scheme. Through this scheme, households can eliminate their annually generated electricity against their annual consumption, but for the return you do pay compensation for many suppliers. However, the netting arrangement will stop in 2027. Settlement is no longer possible, but if you return electricity to the energy supplier you will receive a reimbursement for that. According to the new energy law, the return allowance must be at least fifty percent of the rate that you pay for electricity. In Flanders, the reversing counter, the Flemish version of the netting scheme, has already been abolished in January 2021. There too, a return allowance (the injection rate) is known, where the rate is lower than the current that you take off from the net.

The energy market is therefore in full swing and both home batteries and V2H technologies play a key role in this. The rising energy prices and the need to make the electricity grid more sustainable ensure that consumers are increasingly looking for smart solutions to control their energy costs. Governments and companies invest in subsidies and research, which speeds up the development of new technologies. But such technology does not come from one day to the next. It will take a few years before bidirectional loading for home use becomes established and really works well. So the question is how fast the adoption of V2H will be. The technology is still in its infancy and many consumers are cautious because of the costs and complexity. Nevertheless, experts point out that the combination of electric cars, home batteries and smart energy networks may play a prominent role.

Is the future running on wheels?

After this exercise it may be clear: an electric car as a home battery offers an innovative alternative to traditional home batteries and has a lot of potential. The greater storage capacity, the possibility of mobility and the cost savings make it an attractive option, especially for households that already have an electric car. Yet there are also challenges, such as the availability of the car, the impact on the battery life and the limited availability of bidirectional technology.

That is why it is not a bad idea to wait for that evolution. But if you have the necessary budget and you find the idea attractive, then invest in a home battery. They already seem the safer choice for those looking for certainty. They are easier to integrate into existing systems and offer a stable solution for energy management. However, if the technology and infrastructure around V2H further develop, the electric car can sometimes become the pivot of a smart and sustainable household. Who knows, it will soon be a standard question when purchasing an electric car: “Can he also provide my house with power?”