Researchers report that 53% of European detached homes could provide all their own energy needs in 2020 using only local solar radiation on the roof, and this technical feasibility could increase to 75% in 2050. Publishing on 2 November in the magazine Joule, the study shows that there is no economic advantage for individual households to be completely self-sufficient under current or future conditions, although in some cases the costs are equal to staying on the grid. The researchers estimate that self-sufficiency will be economically feasible for 5% (two million) of Europe’s 41 million detached single-family homes in 2050, if households are willing to pay up to 50% more in price to remain fully grid-dependent.
“Our results show that even in 2050 going off the grid will not be the most economical choice, but it may make sense to invest in these kinds of self-sufficient buildings if you are willing to pay more for self-sufficiency,” says lead author Max Kleinbram , a researcher in energy economics at the Karlsruhe Institute of Technology in Germany.
Grid energy costs are rising as renewable energy technology becomes more affordable. In their quest for self-sufficiency, more and more households are showing interest in producing their own renewable energy sources. The Kleinebrahm team wanted to find out how feasible it would be for individual residential buildings in different parts of Europe to become completely self-sufficient and whether this would bring any financial benefits. Although the potential for Europe’s transition to 100% renewable energy has been examined at continental, national and regional scales, this study is the first analysis at the level of individual buildings.
To identify regions and building types that are more prone to self-sufficiency, the researchers compiled a database of homes across Europe and identified 4,000 homes that are representative of different regions in terms of architecture, household electricity demand, climate and local economy framework. The researchers then designed optimal energy systems for each representative home that fully cover electrical and thermal energy needs while minimizing costs. These systems include measures such as rooftop solar panels, small wind turbines, various types of storage systems, installation of heat pumps, and retrofitting and insulation measures.
The researchers then scaled up their results to assess the technical and economic feasibility of energy self-sufficiency for Europe’s 41 million detached single-family homes. Overall, they estimate that 53% of homes could technically achieve energy self-sufficiency in 2020, and that this proportion could increase to 75% by 2050 with expected improvements in renewable energy and storage technologies. However, becoming fully self-sufficient was more expensive than remaining fully grid-dependent in both 2020 and 2050.
Homes in sunny European countries such as Cyprus, Malta and Italy have the highest economic potential for self-sufficiency, while northern European countries such as Finland, Norway and Sweden (where there is a large mismatch between high winter energy needs and solar radiation) have the lowest potential. Regions with larger roofs, such as Denmark, Slovenia, the Netherlands and France, also have greater potential for self-sufficiency. The researchers also noted that there is more potential for self-sufficient buildings in countries with high grid electricity costs, such as Germany, because there are fewer financial incentives to stay on the grid.
Although achieving full self-sufficiency may not be economically viable, researchers have shown that partial self-sufficiency — where a building remains connected to the electricity grid but also invests in a photovoltaic system, heat pump and insulation — can reduce household energy costs. The optimal degree of self-sufficiency varies for different buildings and regions, but for a representative building in Germany, the researchers calculated that it would be optimal from a cost perspective to be 73% self-sufficient in 2020 and 78% self-sufficient in 2050.
The researchers note that high operator costs make going off the grid more attractive, and say policymakers and utility companies should encourage even fully self-sufficient households to stay connected to the grid. “On a macroeconomic scale, it would be less efficient to have a large number of households abandoning the grid rather than maintaining it,” says Kleinbram.
As the cost of maintaining the grid is shared between users, there is also the potential for grid costs to rise further as households decide to go off grid. “From a social point of view, you have to consider the possibility of very wealthy households going off the grid, in which case the rest of the operation of the grid will have to be paid for by economically weaker households,” says Kleinbram.
This study is unable to answer questions about how the increasing number of self-sufficient homes will affect electricity demand and electricity markets, but the researchers plan to look into these topics in the future.