Abstract Fuel cell based micro combined heat and power (micro CHP) has been the subject of numerous simulation studies. We report on actual practical performance of a proton exchange membrane fuel cell (PEMFC) micro CHP in a UK dwelling over the 2017–18 heating season and compare its performance with a Stirling engine micro CHP which it replaced. Results show that the PEMFC micro CHP achieves a much higher annual electricity output over a year, with household self-consumption and operating economics dependent on electric vehicle charging. Empirical models derived from this operating experience show that the value of this technology is less sensitive to building parameters, occupancy, and climate change when compared to engine-based micro CHP. We consider the potential role of this technology in the decarbonisation of heat, and highlight the benefit of reliable electricity generation injected into low voltage distribution to mitigate winter demand peaks from heat pumps. A comparative analysis of the primary energy efficiency of different methods of meeting domestic energy demand using natural gas with carbon capture shows that a mixed solution to decarbonisation of heat, combining heat pumps, PEMFC micro CHP, and hydrogen boilers, should not degrade energy efficiency substantially by comparison with an all-electric solution and could be more acceptable to consumers.