Solar success may bring an overlooked side effect

Europe’s energy transition has been built around a simple expectation: more rooftop solar should reduce pressure on the wider power system by replacing grid-supplied electricity with generation produced at home. New research highlighted by

pv magazine

suggests the picture may be more complicated. The study says the “solar rebound effect,” in which households increase total electricity use after installing solar, could materially raise Europe’s long-term power demand.

Researchers from FernUniversität in Hagen modeled different levels of this rebound effect in an open-source optimization model of Europe’s energy system. Their conclusion is that the added demand could range from 63 terawatt-hours to 314 terawatt-hours by 2050. In the study’s worst-case scenario, that would lift Europe’s total electricity demand by up to 5.1%.

The finding matters because Europe is planning not only for cleaner electricity, but also for a more electrified economy. Heat pumps, electric vehicles, storage systems, and industrial electrification are all expected to add load over time. If rooftop solar adoption also changes household behavior in a way that increases consumption, planners may be undercounting a meaningful source of future demand.

Why households might use more power after going solar

The rebound effect is not a claim that solar systems fail to reduce emissions or lower grid demand. Instead, it describes a behavioral shift. Once households generate some of their own electricity, they may feel more comfortable using additional appliances, shifting more activity to electricity, or being less restrained about consumption during sunny periods.

The study frames this as a blind spot in European energy-system planning and abatement scenarios. That is significant because household solar is usually treated as an unambiguous demand reducer. If part of the economic benefit of solar leads consumers to use more electricity overall, the net system effect still may be positive, but it is no longer as straightforward as many planning models assume.

The researchers also estimate that the resulting system costs could reach as much as €23.5 billion per year. Those costs would come from the need to build more renewable generation and more grid flexibility to serve the extra load.