This paper examines experience in solar renewable energy certificate (SREC) markets in the United States. It describes how SREC markets function--key policy design provisions, eligible technologies, state and regional eligibility rules, solar alternative compliance payments, measurement and verification methods, long-term contracting provisions, and rate caps. It also examines the trends of SREC markets--trading volumes, sourcing trends, trends in the size of solar photovoltaic (PV) systems driven by these markets, and trends in price and compliance. Throughout, the paper explores key issues and challenges facing SREC markets and attempts by policymakers to address some of these market barriers. Data and information presented in this report are derived from SREC tracking systems, brokers and auctions, published reports, and information gleaned from market participants and interviews with state regulators responsible for SREC market implementation. The last section summarizes key findings.