Solar Renewable Energy Certificates (SRECs) or Solar Renewable Energy Credits are a form of Renewable Energy Certificate or "Green tag" existing in the United States of America. SRECs exist in states that have Renewable Portfolio Standard (RPS) legislation with specific requirements for solar energy, usually referred to as a "solar carve-out". The additional income received from selling SRECs increases the economic value of a solar investment and assists with the financing of solar technology. In conjunction with state and federal incentives, solar system owners can recover their investment in solar by selling their SRECs through spot market sales or long-term sales, both described below.