There is an increasing amount of talk about vehicle to home (v2h) power backup with a bidirectional electric vehicle charger. A bidirectional EV charger allows for power to flow between an electric vehicle, home, and the grid. The marketing angle on this is great, you arrive home to a blackout, plug in your electric vehicle, and all your lights come back on. The batteries in electric vehicles are large and can likely power your home for multiple days in the event of an outage. It is super compelling and rightly so, but does this solve your home’s backup energy needs?

Not alone. It is, however, going to be a great tool to supplement home battery storage. Here is why.

Solar production is highest during the middle of the day when your electric vehicle is most likely away with you at work. Homes, however, use a low amount of energy during this time that solar is cranking out a high amount of power. If homeowners don’t capture this power, they lose a lot of value. This is because in Shade Power’s territory in the San Francisco Bay Area and most other territories, utilities provide credits for energy exported to the grid but only at very low rates. So, our customers are investing in ways to keep their solar energy generation on their side of the electric meter.

The main way to do this is by installing battery storage. The batteries we install charge up with the solar energy the home does not need throughout the day and in the evening, the home runs off the stored energy in the batteries. This allows homeowners to use their generated solar power instead of purchasing from the electric grid when solar production stops. The other strategy to utilize high daytime solar output is shifting when your home uses energy. This is limited mostly to tasks that are on schedules such as pool pumps and EV charging.

So, the optimal setup will be to have solar modules installed with battery backup power and the addition of a EV charger with bidirectional capability when it becomes available. This allows your home to capture excess solar energy that is produced during the day while your electric vehicle is away from your home. Then, in the event of a power outage or if your home battery storage is depleted during the night, the bidirectional charger dramatically extends your storage capacity. Essentially, when there is a power outage your electric vehicle is like a generator you start up and plug into your service panel to run your home until the outage is resolved, but way sleeker and quieter.

Bidirectional chargers with electric vehicles are a very nice power back up option because electric vehicles often have batteries large enough to run an average California home for a few days. If you are also generating solar energy during the day, you could go through a very long power outage without any change in lifestyle. However, another reason you would want this to only complement instead of replace home energy storage is that in an outage, you wouldn’t want your home’s power to shut off just because you had to drive your electric vehicle somewhere.

We specialize in installing Enphase equipment and all projects we install come with the Enphase App to easily monitor and manage your solar and battery storage installation together. Enphase’s EV chargers once installed can also be managed through this app, allowing for intelligent switching between modes based on site conditions and preferences. One thing to keep in mind though is that not all electric vehicles will allow for bidirectional charging. Currently, vehicle manufacturers and energy management manufacturers like Enphase are working together to establish standards for this concept but this is not yet finalized.

Enphase’s bidirectional charger will be out soon. If you would like to learn more, please don’t hesitate to contact us to schedule an appointment.