Ohio Rev. Code Ann. § 156.04
(B) Any installment payment contract under this section shall provide that all payments, except payments for repairs and obligations on termination of the contract prior to its expiration, are to be a stated percentage of calculated energy, water, or wastewater cost savings, operating costs, and avoided capital costs attributable to the one or more measures over a defined period of time and are to be made only to the extent that those calculated amounts actually occur. No such contract shall contain either of the following: