Not exactly. Since it was a subsidized system, with 'Net Metering', my utility sets the billing rules. Excluding the finer points, here's the gist of how the billing works:
* My utility (Los Angeles DWP) accumulates a 'dollar banking' credit for the present value of net energy [signed power flow integrated over the two-month interval of my utility's billing period] fed back to the grid when a billing statement period is net-energy-productive (i.e. the PV system made more energy than my home consumed over the statement-period of two months). I pay a $22 'minimum charge' (normalized: $11/mo) for, as I see it, my share of utility equipment amortization and operations I'd otherwise be paying as a consumer. Fair enough: I do draw energy when the sun goes down. It's co-operative.
* In the summer, my 5-ton A/C use exceeds my PV system's production capacity; I become an energy consumer during one or two billing periods. My utility calculates the price for the _net_ energy I use per period, then debits the 'dollar banking' account. If that gets exhausted, then I pay the residual, otherwise my 'dollar banking' balance just goes down.
* My utility (Los Angeles DWP) accumulates a 'dollar banking' credit for the present value of net energy [signed power flow integrated over the two-month interval of my utility's billing period] fed back to the grid when a billing statement period is net-energy-productive (i.e. the PV system made more energy than my home consumed over the statement-period of two months). I pay a $22 'minimum charge' (normalized: $11/mo) for, as I see it, my share of utility equipment amortization and operations I'd otherwise be paying as a consumer. Fair enough: I do draw energy when the sun goes down. It's co-operative.
* In the summer, my 5-ton A/C use exceeds my PV system's production capacity; I become an energy consumer during one or two billing periods. My utility calculates the price for the _net_ energy I use per period, then debits the 'dollar banking' account. If that gets exhausted, then I pay the residual, otherwise my 'dollar banking' balance just goes down.