One of the most significant drivers of renewable energy growth in the US has been the state renewable portfolio standards (RPS) — also known as renewable electricity standards. An RPS is a regulatory mandate to increase the production of energy from renewable sources, such as wind, solar, biomass and other alternatives, as opposed to fossil and nuclear electric generation. The policies require or encourage electricity producers within a given jurisdiction to supply a certain minimum share of their electricity from these designated resources. For further details, see the detailed explanation from the US Energy Information Administration.

There is now a distinction between RPS policies and Clean Energy Standards (CES). The difference being how the state in question defines what is renewable and what is clean. Some clean sources may not be deemed renewable. In most cases, a CES policy will include RPS as part of the policy. As of 2022, 30 states, the District of Columbia, and two territories have active renewable or clean energy requirements, while an additional three states and one territory have set voluntary renewable energy goals. Interestingly, some states are expanding their RPS goals, while others are moving to eliminate them. For further details, see State Renewable Portfolio Standards and Goals.