Electric vehicle owners are getting some new performance options to pick from—not in their vehicle but in their home. Bidirectional charging systems are giving EV owners the option to supply power to their home—making use of that big battery in their vehicle while it’s just sitting in the garage.
Let’s look under the hood, or “frunk” with EVs, at these bidirectional systems.
These bidirectional charging systems, sometimes referred to as “vehicle-to-home” (V2H) currently require a compatible EV charger (EVSE) and some form of transfer switch electrical panel. This equipment gets the DC current out of the EV battery and converted into AC current that your house runs on.
There are several brands of equipment on the market now, and this is sure to keep increasing as EV manufacturers move to enter the growing “home electrification” market. Whole new divisions have been formed by automakers including GM Energy, Tesla Energy, and Ford Energy Solutions.
Tesla has dubbed their system “Powershare.” GM Energy is going with “V2H” and Ford has adopted “home backup power.” You can purchase the first two as of this writing, though the Ford solution seems to be in a “coming soon” status.
Digital automation and energy management giant Schneider Electric just released a new Schneider Pulse electrical panel for your home that will allow whole home backup from storage batteries, generators and EV chargers and is releasing their own EV charger as well that will support bidirectional charging.
EV-Specific Systems
Currently you need to have the system created for the EV you have. Tesla’s system does not work with non-Tesla EVs, though they’ve mentioned that Powershare support of non-Tesla EVs is coming. Hopefully this cross-brand approach to compatibility will be common, or EV owners could have a challenge purchasing an EV from a different automaker that is no longer “compatible with their house” due to their bidirectional system being designed for their previous EV.
Electricity from your EV is not designed to power your entire house.
Depending on the area you live it, you might not even be able to use the energy from your EV on any circuit you wish. This is because the battery in your EV can only provide a limited amount of energy. Currently with Tesla that amount is 48 amps and 40 amps with GM Energy. These amounts are very useful in a blackout and can run your lights and refrigerator for quite a while, just don’t think you can fire up an electric clothes dryer and cooktop without putting a serious dent in your ability to hold out until grid power is restored.
You will need to be selective in what electrical devices you turn on using the backup power from your EV. The bidirectional charging systems have smartphone apps to help you monitor your power usage, and if you’re mindful of the larger energy consumers in your house like the dishwasher, electric clothes dryer, electric cooktop, and air conditioner; you can make wise choices pretty easily.
In some areas, San Francisco for one, the city or county regulations will help you make that choice, whether or not you think you need help. Those areas require that a select number of circuits be given access to the power from your EV. These circuits must be bundled together in what’s called a “critical loads panel” and when grid power cuts out, only that panel receives power from your EV.
Installation and routing of circuits into these critical loads panels can increase the cost of your system.
Frequently, the air conditioners consume too much electricity when starting up and are not able to be powered by the EV either. A certified installer for your bidirectional system can determine this with a look at the labels on your air conditioner units.
If you don’t have many power outages in your area, bidirectional charging may still be worth looking into.
It’s possible to use these systems to reduce your energy bill by powering some circuits in your house from your EV rather than from the grid when energy prices are high for grid power. Or perhaps charge your EV overnight when grid power is less costly, then sell some back to the grid during the peak pricing times.
Not every EV supports bidirectional charging.
As mentioned, support for bidirectional charging looks to be growing among automakers. In fact, they look to be rushing to build it into their new EV models and their EV chargers. So, keep that in mind when shopping for EVs. Both the vehicle and charger must support bidirectional charging.
Additionally, the cost of installation for each system can vary quite a bit. The amount of work and material required from a licensed electrician to install these systems will differ depending on the system and the specific details of your house’s electrical wiring and the locations of your electrical panels and garage.
Bidirectional charging looks to be a promising new option for EV owners. It’s worth thinking about an EV as more than just transportation and start looking into the fast-approaching options for using that big battery to power more than just your ride.
We at Wells Electrical are getting previews of many systems being brought to the market for bidirectional charging and we’re happy to help you take advantage of it when you’re ready.
