I guess that didn't quite answer the question: The $2400/year were around $0.30/kWh on the E1 tiered default plan. We did switch to the E6 and after that to EV-A plan which is a time of use plan with $0.46 peak, (3pm to 7pm), $0.25 mid-peak ($7am to 3pm, 7pm to 11pm) and $0.12 otherwise.
We now charge at night since that is the cheapest. Net-metering makes it so that we get more than what we produce since it is accounted for at $0.25 to $0.46, so we get credited roughly $0.30 since we start producing about 8am and stop producing about 8pm in the summer, peaking around noon. about 60kWh/day in the summer, 20kWh/day in the winter.
Thanks. Since we have residential retail competition among generators with energy around $0.07/kWh, no residential TOU rates, and no state incentives, the pay-back period here computes considerably longer .