Tex. Local Government Code § 302.004

(a) An energy savings performance contract may be financed:

(1) under a lease-purchase contract that has a term not to exceed 20 years from the final date of installation and that meets federal tax requirements for tax-free municipal leasing or long-term financing;

(2) with the proceeds of bonds; or

(3) under a contract with the provider of the energy or water conservation or usage measures that has a term not to exceed the lesser of 20 years from the final date of installation or the average useful life of the energy or water conservation or usage measures.

(a-1) Notwithstanding other law, the governing body of a local government may use any available money to pay the provider of the energy or water conservation measures under this section, and the governing body is not required to pay for such costs solely out of the savings realized by the local government under an energy savings performance contract. The governing body may contract with the provider to perform work that is related to, connected with, or otherwise ancillary to the measures identified in the scope of an energy savings performance contract.

(b) An energy savings performance contract shall contain provisions requiring the provider of the energy or water conservation or usage measures to provide a guarantee. If the term of the contract exceeds one year, the local government's contractual obligations in any one year during the term of the contract beginning after the final date of installation may not exceed the total energy and water savings, the net operating cost savings, and the stipulated or agreed upon increase in billable revenues resulting from the estimated increase in meter accuracy, divided by the number of years in the contract term.