The number of Renewable Obligation Certificates (ROCs) issued to generators rose 13% in the 2014/15 financial year.
It increased to more than 71 million, new data from DECC revealed.
The ROCs are designed to encourage generation of electricity from eligible renewable sources in the UK. They are issued by Ofgem.
Overall generation rose to 55,785GWh.
In the fourth quarter of 2015, the number of ROCs rose by 17% to 25.3 million, increasing generation by 16% to 19,426GWh compared to the same period in 2014, it added.
The number of ROCs increased by 49% to above nine million in November 2015 from the same month in 2014.
Overall generation increased by 47% in the same period to 6,885GWh.