Part of the system I am modelling uses micro-CHP. I have looked at the cogeneration sample given within the programme, but am unsure about the inputs for the microturbine 'Fuel' section. I am using natural gas, and have a maximum consumption rate of 2.7m3/hr, when the burner output of 6.5kW is generating 1kW of electricity. Is the 'size' of the turbine the kW electrical or kW thermal please? I.e. is the size of my microturbine 6.5kW or 1kW from HOMER's point of view?

Good question. That is a 1 kW generator as far as HOMER is concerned. If you set the heat recovery ratio correctly it should put out 6.5 kW thermal at full power output.