The Impact of Renewable Power Generation on the Profitability of Solar District Heating - An Economic Point of View

The intermittency of power generation by wind and photovoltaic results in volatile spot prices at the power exchanges. As a consequence amendments in the operational strategies of power plants are required. For combined heat and power (CHP) units in district heating (DH) networks this means that production is particularly profitable in periods with high spot prices. In situations with low spot prices, in turn, it can be more cost-efficient to operate available peak load boilers instead of the CHP to supply the required heat. These circumstances can make solar district heating economically attractive. Additional flexibility in DH systems based on CHP is achieved by integrating electric boilers and heat pumps into the operational strategy. In this paper concepts for technically and economically optimized “smart” DH systems including solar are presented. The interaction of heat producers in different configurations of DH systems is simulated with a dynamic simulation tool (TRNSYS 17). To investigate the profitability of solar district heating, heat costs of different configurations of DH systems with and without solar are computed. The simulations reveal that in smart DH systems solar heat can displace expensive heat from peak load boilers. It is further shown that solar collectors do not only reduce operating costs of DH systems but are even profitable from a full cost perspective. Sensitivity tests point out that increasing prices of fossil fuels as well as higher shares of PV in power generation prove advantageous to solar district heating.