(a) At any time after an initial complaint is filed under Section 36.151, the regulatory authority may issue an interim order establishing temporary rates for the electric utility to be in effect until a final determination is made.
(b) On issuance of a final order, the regulatory authority:
(1) may require the electric utility to refund to customers or to credit against future bills:
(A) money collected under the temporary rates in excess of the rate finally ordered; and
(B) interest on that money, at the current interest rate as determined by the commission; or
(2) shall authorize the electric utility to surcharge bills to recover:
(A) the amount by which the money collected under the temporary rates is less than the money that would have been collected under the rate finally ordered; and
(B) interest on that amount, at the current interest rate as determined by the commission.