Hello and welcome to Just Answer. My name is ***** ***** I will be happy to assist you with your electrical question.
1) Rather than using an electric car battery to provide supplemental power to the home, why not increase the existing PV system by adding additional panels, a larger inverter and a larger battery bank to support the required loads? In other words, increase your PV kW output?
2) If using 3 separate power systems to the home such as the grid, PV panels and possibly an electric car battery, this application now requires more costly components to isolate all 3 systems from each other. Electric lithium car batteries are also very expensive when it comes time to replace them. Much more cost effective to increase the existing PV battery bank in my opinion.
3) Another option is to install the Tesla Powerwall system. This is still a costly application, but you wouldn't be using the electric car battery. The internal Powerwall battery can be charged directly from the PV panels.
See the Tesla link shown below:
4) I do not recommend using an electric car battery as these cost big bucks $$$$ to replace. Instead, leave the car battery to only serve the car as it was originally designed for.
If you have any additional questions, just let me know and I’ll be glad to answer them for you.
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