Cogenerating systems based on renewable energy resources get more and more interesting also for small to micro scale applications. In this publication a biomass pellet burner with a nominal heat output of 35 kWth driving a Stirling engine with 5 kWel is presented. The combustion was adapted to the requirements for a totally embedded and efficient Stirling process. First, high flue gas temperatures of about 1,100°C are requested for the aspired electrical efficiency of 15%. Second, particle matters in the flue gas have to be avoided as they deposit on the heat exchanger decreasing the heat transfer and subsequently the efficiency. All the defined measures for adapting the combustion conditions as well as their evaluation by tests with two prototypes are shown.