Solar Renewable Energy Certficates (SRECs) are a component of state-specific legislative programs (Renewable Portfolio Standards) implemented to incentivize investment in renewable energy production facilities. RPS programs mandate that utilities source a certain percentage of their electricity from renewable resources, increasing over time. State programs can vary widely and some place particular emphasis on specific resources, such as solar PV.
SRECs are essentially the "environmental attribute" associated with qualified solar PV facilities. One SREC is created for every mega-watt hour of electricity by a solar PV facility. SRECs can trade separately from the sale of the actual electricity generated, and be used to satisfy utilities' annual RPS requirements.