I'm wondering what it takes for an EV to be able to be used as a home backup battery. It seems like in principle this could be relatively straight forward, but I suspect that the devil is in the details.

Does an EV have to be designed with this use case in mind -- is additional hardware required to support it? Or, is it possible to use any EV that supports Level 3 (DC high voltage) charging as a backup battery?

As an example, Enphase has announced the IQ EV Charger which seems to do exactly this, but the web page neither says "these cars are supported" or "works with any CCS EV."

  • I'm wondering if this question would be a better fit for DIY.SE? Apr 16 at 10:10
  • Or electronics.se? I agree it's not a good fit here as it's about how to connect an external battery into a house supply, it doesn't matter if that battery has wheels.
    – GdD
    Apr 16 at 10:52
  • 2
    Actually, the question is -- IMHO, at least -- about the evolution of EV features. There is a box in the EV that manages the charging of the battery, and it's not obvious to me that that box would "naturally" allow the battery to be both charged and discharged through the charging port. At the very least, it seems to me, that there must be safety issues involved that mean that the battery voltage is not present at the charge connector until the charging contactors are closed.
    – dlu
    Apr 16 at 15:17
  • In addition to vehicle design issues, there are also backfeed issues. Normally an interlock is used to prevent running a generator when utility power is off without first making sure the utility power is disconnected. That is important because if you rely on "flip the main breaker" and forget to do so and someone is working on the utility lines they get zapped. EV service equipment that handles vehicle-to-home will need to manage that aspect extremely carefully. Apr 17 at 4:40
  • @manassehkatz-Moving2Codidact my solar+battery installation uses a simpler system - it feeds an emergency power socket not the whole house. I chose to have it located near the freezer , being the most likely not-really-portable thing I'd want to power in a power cut (also the control system for the gas central heating is nearby).
    – Chris H
    Apr 19 at 14:17


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