Microprocessor-based control sub-systems which control the thermal and electrical output of integrated micro-combined heat and power generation (M-CHP) systems used to supply domestic electrical power, domestic space heating (SH) water, and domestic hot water (DHW). The M-CHP system uses a microprocessor controller to control the internal operating conditions, such as pump speeds, gas flow rate, and evaporator outlet temperature. Controlling these parameters enables setting the capacity of the system at any instant in time, thereby permitting load following, using a variable capacity operation. The controller also monitors through sensors a number of additional safety controls and system protection devices, such as relays/contactor of the alternator to grid, and electrical trips to the feed pump, the oil pump, the hydronic pump, the blower, the gas valve, the expander bypass valves, and other electrically powered devices in the system.