Almost all of today's renewable energy projects rely on regulatory financial incentives in order to make investment returns sufficiently attractive. Some incentives, such as rebates and tax credits, have known monetary value and are therefore rather easily incorporated in financial pro formas. Other incentives, namely renewable energy certificates (commonly known as "RECs") used for compliance with renewable portfolio standards (RPS), are inherently variable and therefore require exogenous methods to determine their value. Because RECs can be unbundled from the underlying renewable power and sold to utilities with renewable energy obligations, they are commodities subject to a variety of market forces that impact their value.