(1) A customer shall pay, on the date provided in the solar agreement, the costs of the solar energy system's:
(a) design, not to exceed the greater of $1,500 or 3% of the total cost of the solar agreement;
(b) equipment procurement, not to exceed 25% of the total cost of the solar agreement; and
(c) installation, not to exceed 80% of the total cost of the solar agreement inclusive of payments due in accordance with Subsections (1)(a) and (1)(b).
(d) A solar retailer may not collect the remaining balance of the solar agreement from a customer until the residential solar energy system is producing usable energy.