Warum mit einer Solaranlage die Brennstoffeinsparung weit über den Solarertrag hinaus gehen kann – ein neuer Denkansatz für die Marketingabteilung

In this paper the realistic behaviour and efficiency of heating systems were analysed, based on long term monitoring projects. Based on the measurements a boiler model was evaluated. Comparisons of measured and calculated fuel consumptions showed a good degree of similarity. With the boiler model, various simulations of a one family house with/without a solar domestic hot water heating system (SDHW) were done for different hot water demands (1500 and 3000 kWh/a), a space heating demand of 16000 kWh/a and collector sizes of 2 and 4m2 with a 200 liter tank. The result shows that the potential of fuel reduction can be much higher than the solar gain of the solar heating system. For some conditions the fuel reduction can be up to the double of the solar gain due to a strong increase of the system efficiency. As the monitored boilers were not older than 2 years, it can be assumed that the saving potential with older boilers could be even higher than calculated in this paper. The results show very clearly that the lower the system efficiency of the reference system is, the higher the additional reduction potential of the fuel consumption by improving the system efficiency is when a SDHW-system is added to the system. Further large savings (also based on primary energy) can be achieved by switching off the boiler in summer time and using an electric heater instead.