I'm on NEM2.0 so I can generate more than I use at peak hours and push into the grid for higher credit value than I consume overnight to charge my car.

Still, I don't see the value proposition for batteries on NEM2.

If I wasn't using _any_ electricity at my house, and I could 100% charge the batteries off-peak and push the power back to the grid at peak, I'd only be arbitraging like 5-10c/kWh * 15kWh per pack.

So, $1.50 per day, per pack. Unless I'm totally thinking about this wrong. The spread between peak and off-peak rates is just too small.

PG&E does net metering, but even at a sub 1:1 rate past your net usage it does not make sense that it costs more to send energy back to the grid

My provider wasn't PG&E, and I don't know if they do the same, but there's a fixed $30/mo service fee for connecting to the grid, regardless of how little power is used, even if its negative.

The worst that happens is you get paid back at the wholesale rate (from your bill, not live market price) instead of discounting kwh-per-kwh.

But is that rate always positive? Where I'm from during peak sun hours, the rate is negative and you end up paying money to deliver money to the grid. They do this to incentivise you to decouple your solar installation during peak sun hours so the net doesn't get flooded with too much energy.

In CA it can be 0 but not negative.

Depending on when you signed up for NEM you may have a guaranteed floor like 4¢/kWh or even much more.

The $30+ minimum on my bill was from a service fee, for connecting to the grid regardless of how little power was used.

Yes, you asked about California. I assume you are not in California.

Is the disconnect automatic? what happens when you're not connected to the grid but battery is full?

This is for solar only installations. People are advised to flip the breaker of their solar installation when energy prices are negative as it would cost them money if they deliver electricity to the grid. This helps to reduce strain on the grid.