Theoretical analysis of a solar-hydrogen system for remote power supply shows that the thermal waste of the fuel cell is almost equal to or more than its electricity production. Utilising this heat for hot water production or space heating could greatly enhance the system’s overall energy efficiency and economic attractiveness. A computer model of a solar-hydrogen system supplying both low-temperature heat and power is presented. The model, based on Visual Pascal (Delphi 7), provides a user-friendly interface. The PV module is represented by a series resistance and diode model. The PEM electrolyser and fuel cell have been modeled using modified Butler-Volmer equations in which saturation behavior of the polarisation curves is considered. Simulation results for the main components of a solar-hydrogen combined heat and power (CHP) system based on a 500W BCS PEM fuel cell are compared to experimental data to ensure the model’s validity. Both manufacturer’s data and theoretical analysis show that the electrical efficiency of the fuel cell varies from just under 30% to just above 55% over the range of operational currents. Theoretical analysis shows that around 50% of the heat generated by the fuel cell is recoverable for use in low-temperature heating applications. The overall energy efficiency of solar-hydrogen CHP system can increase by 50%, which is a considerable gain compared to a power-only application. A small-scale demonstration solar-hydrogen CHP rig based on the BCS 500W fuel cell is now under construction to obtain experimental results on performance to compare with model predictions.