One possible configuration of a combined solar and wood pellet system is shown in Figure 1, and other common solutions can be found in [10]. The systems can either be integrated, with the pellet burner integrated in the storage tank, as in the figure, or consist of separate sub-systems connected with a joint accumulator tank. Technically, the solar and wood pellet systems complement each other well. The solar collectors can supply all heat during summer using an electrical back-up heater. The pellet boiler, which usually operates with a lower efficiency and many starts and stops during summer, can then be completely turned off all season. Combined systems thereby result in an increased system efficiency. Both heating systems are additionally regarded sustainable and relatively cost-efficient, and for Swedish conditions, where large areas of forest are grown, biomass is a vast domestic energy resource. Biomass is however considered a limited resource, and by introduction of 10 m2 solar collectors in a pellet heating system, the pellet consumption can be reduced by 25 % according to [6].

3. Results

In the following, interview results for four topics are compiled; the present situation and obstacles, means to increase the use, costumers in the purchase phase and how to reach success. All statements in this section are from the informants and quotations have been translated to English by the author.