A Renewables Obligation Certificate (ROC) is a green certificate issued to an accredited generator for eligible renewable electricity generated within the United Kingdom. As standard, one ROC is issued for each MWh of eligible renewable output generated but some technologies get more, some less. For instance, microgeneration and offshore wind installations receive 2 ROCS per MWh; onshore wind installations receive 1 ROC per MWh and sewage gas-fired plants receive half a ROC per MWh. One ROC currently trades for about £45.
Most ROCS are issued for large scale generation but some communities will be earning ROCS from small scale technologies installed before 15th July 2009.