Notwithstanding section 1309 (relating to rates fixed on complaint; investigation of costs of production), the commission, by regulation, shall provide for a utility to remove the costs of capital additions from its rate base and to refund any revenues collected as the result of this subsection, plus interest, which shall be the average rate of interest specified for residential mortgage lending by the Secretary of Banking in accordance with the act of January 30, 1974 (P.L. 13, No. 6), referred to as the Loan Interest and Protection Law, during the period or periods for which the commission orders refunds, if the commission, after notice and hearing, determines that the capital addition has not been completed within a reasonable time.
66 Pa.C.S. § 521