Renewable Energy Certificates (RECs) are a market-based instrument to promote RE power. The REC is a policy instrument which provides evidence that an electricity generator has produced a certain quantum of power from a renewable energy source such has wind, solar, biomass, waste to energy etc.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/rec-mechanism-india
[2] http://admin.indiaenvironmentportal.org.in/category/journal/inwind-chronicle
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/market-based-instruments
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/climate-change
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/renewable-energy
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india