Section 4(4)(a) in The Central Electricity Regulatory Commission (Terms And Conditions For Tariff Determination From Renewable Energy Sources) Regulations, 2009
(a)"Useful power output" is the gross electrical output from the generator. There will be an auxiliary consumption in the cogeneration plant itself (e.g., the boiler feed pump and the FD/ID fans). In order to compute the net power output it would be necessary to subtract the auxiliary consumption from the gross output. For simplicity of calculation, the useful power output is defined as the gross electricity (kWh) output from the generator.