The role of Swedish single-family dwellings in the electricity system - The importance and impacts of solar photovoltaics, demand response, and energy storage

Abstract: This thesis investigates the role Swedish single-family dwellings can play in the electricity system. Both through becoming electricity producers through the use of solar photovoltaic (PV) systems, and the possibilities of demand response (DR) and energy storage in combination with this, and through the DR of electric space heating in the dwellings. The methodology used builds on the use of optimization models, which describe the relevant parts of the dwellings and technical systems, measured household load profiles, and modeled space heating demand. The developed models are linked to an existing model that performs a cost optimal dispatch of the electricity generation system. Thereby, allowing for co-optimization of the dispatch of supply side electricity generation and DR, and the evaluation of impacts on the supply side of the system from actions taken on the demand side and vice versa.

The results indicate that given that there is added value in self-consumption of PV generated electricity, i.e., not paying taxes and variable grid fees on self-consumed PV generated electricity, an expansion of household PV systems in Sweden that is driven by economic incentives appears to be robust with regards to the composition of a future electricity system. The households’ economic potential for battery investments is found to be dependent to a large degree upon the economic value of utilizing them for arbitrage and in the economic value of increased self-consumption of PV generated electricity. Furthermore, a practical limit on the ability of batteries to increase the self-consumption of PV generated electricity in Swedish households is identified. For the DR of household loads the economic value provided to a household’s investment in a PV system is small, except in the case of hydronic heating loads. It is also shown that for future evaluations of large scale investments of household PV-battery systems there is a need to include feedback mechanisms between the supply and demand sides of the electricity system.

A significant DR potential is identified for the electric space heating in the dwellings. The economic value of the DR is found to depend on the future electricity system composition. In a future system that is dominated by variable wind power, DR offers economic value through decreasing the number of start-ups, obviating the need for part-load operation of thermal power plants, and avoiding the operation of peaking gas power plants. In an electricity system less dominated by wind power the value of DR is low. The DR is found be used to a large extent for valley filling, increasing load during low load hours, and peak shaving, decreasing load during high load hours.