Renewable portfolio standards (RPS) programs obligate utility companies to derive a significant portion or target percentage of their total electricity from clean fuels by a given date.

For example, here in Colorado, Amendment 37 mandates that the utilities generate 10% of their electric energy from renewables by the year 2015.

In the United States, 28 states have implemented RPS programs to date.

One of the pitfalls (from the solar energy prespective only) is that much of the percentage of energy generated through RPS programs comes from centrally generated power, such as wind turbines. However, Colorado’s Amendment 37 made an explicit “carve-out” for solar contribution to the RPS target.