The commission may adopt or amend rules governing net energy billing. Rules adopted or amended under this subsection are routine technical rules as defined in Title 5, chapter 375, subchapter 2-A. "Net energy billing" means a billing and metering practice under which a customer is billed on the basis of net energy over the billing period taking into account accumulated unused kilowatt-hour credits from the previous billing period. [2011, c. 262, §1 (NEW).]