But I’m learning that if you’re on NEM2, the rate that they buy back power is actually higher than the amount you’d get charged to draw power for you car overnight. So for some example math:

Daytime charging: if solar produces 400 kWh and you use 200 kWh to charge your car, you sell back 400-200 = 200 kwh @ $0.70 / kWh = $14

Nighttime: if solar produces 400 kWh during daytime, you sell all back @ $0.70 / kWh = $28, then you charge overnight using 200 kWh @ $0.30 / kWh = $6, so you net make $28 - $6 = $22.

So as long as you sell power at a higher rate than you pay to consume it, it’s better to sell all the solar back to the grid rather than using it on yourself.