Sec. 17. The commission shall review a petition filed under section 16 of this chapter by an electricity supplier and, after notice and a public hearing, shall approve a rate to be credited to participating customers by the electricity supplier for excess distributed generation if the commission finds that the rate requested by the electricity supplier was accurately calculated and equals the product of:
(1) the average marginal price of electricity paid by the electricity supplier during the most recent calendar year; multiplied by
(2) one and twenty-five hundredths (1.25).