The document discusses renewable energy sources and capacity in India. It notes that as of May 2013, wind power made up the largest share of renewable energy capacity at 18,552 MW or 69% of the total. It also provides details on India's renewable purchase obligation (RPO) targets set by various states, which require distribution companies and obligated entities to purchase a certain percentage of electricity from renewable sources. The document outlines the regulatory framework and features of India's renewable energy certificates (REC) mechanism, which allows obligated entities to purchase RECs on power exchanges to meet their RPO targets. It identifies challenges with REC compliance and discusses potential alternatives and avenues to strengthen the REC framework and further promote renewable energy in India.