Buy a powerwall or equivalent, they are designed for this use case, they tune the battery chemistry, cooling, weight, etc for this use case. Wearing out a expe

Buy a powerwall or equivalent, they are designed for this use case, they tune the battery chemistry, cooling, weight, etc for this use case. Wearing out a expensive electric car, with a high load, while it's not moving (harder to cool), to save a few pennies per Kwh isn't worth it. Keep in mind that there's power losses just charging and discharging, so you need a pretty big swing to make it worth while. A powerwall (11kwh) costs $7500 or so installed and is generally enough to "peak shave" by charging when power is cheapest and discharge when it's most expensive. It does lower electric bills, but generally isn't really a good financial decision unless you put a financial benefit of having power when during outages.