(1) Except as otherwise provided in this chapter, the rules in this chapter apply to any utility that is subject to the commission's jurisdiction under RCW 80.01.040, 80.04.010, and chapter 80.28 RCW, and qualifying facilities as defined herein. The rules in this chapter do not supersede contracts existing before the effective date of this rule. At the expiration of such an existing contract between a utility and a qualifying facility, the provisions of this chapter shall apply to rates and terms offered under any contract extension or new contract.

(2) Nothing in this chapter prohibits a utility or a qualifying facility from agreeing to voluntary contracts with rates, terms, or conditions that differ from the provisions in this chapter.