Consistent with the other provisions of this chapter, the net energy measurement must be calculated in the following manner:
(1) The electric utility shall measure the net electricity produced or consumed during the billing period, in accordance with normal metering practices.
(2) If the electricity supplied by the electric utility exceeds the electricity generated by the customer-generator and fed back to the electric utility during the billing period, the customer-generator shall be billed for the net electricity supplied by the electric utility, in accordance with normal metering practices.
(3) If electricity generated by the customer-generator exceeds the electricity supplied by the electric utility, the customer-generator:
(a) Shall be billed for the appropriate customer charges for that billing period, in accordance with RCW 80.60.020
(b) Shall be credited for the excess kilowatt-hours generated during the billing period, with this kilowatt-hour credit appearing on the bill for the following billing period.
(4) If a customer-generator requests, an electric utility shall provide meter aggregation.
(a) For customer-generators participating in meter aggregation, kilowatt-hours credits earned by a net metering system during the billing period first shall be used to offset electricity supplied by the electric utility.
(b) Not more than a total of one hundred kilowatts shall be aggregated among all customer-generators participating in a generating facility under this subsection.
(c) Excess kilowatt-hours credits earned by the net metering system, during the same billing period, shall be credited equally by the electric utility to remaining meters located on all premises of a customer-generator at the designated rate of each meter.
(d) Meters so aggregated shall not change rate classes due to meter aggregation under this section.
(5) On April 30th of each calendar year, any remaining unused kilowatt-hour credit accumulated during the previous year shall be granted to the electric utility, without any compensation to the customer-generator.