Solar rebound effect could increase need for batteries, raise Europe’s grid demands 5% by 2050

The solar rebound effect, which occurs when rooftop solar adoption increases household electricity consumption, could create additional system costs in Europe of up to €23.5 billion ($27.6 billion) a year, new research has found.

Mensur Delic and Michael Bucksteeg, from FernUniversität in Hagen, Germany, studied the phenomenon’s role within Europe’s energy system by integrating various solar rebound effect intensities into an open-source optimization model of Europe’s energy system. 

The research found the solar rebound effect may increase electricity demand by 63 TWh to 314 TWh by 2050, increasing Europe’s total demand by up to 5.1%, under the worst-case scenario. This additional demand would require additional renewable generation and grid flexibility, which could increase total power system costs by €6.7 billion to €23.5 billion annually between 2030 and 2050.

Delic and Bucksteeg told pv magazine their work highlighted that the solar rebound effect is not currently accounted for in official energy system planning and abatement scenarios, leaving a significant blind spot. The pair added that it is not just the magnitude of the rebound that matters, but critically also its timing. 

“When households consume additional electricity during sunny hours, the system can absorb this demand at relatively low cost,” they explained. “However, when rebound consumption shifts into evenings or winter periods, driven by higher baseline demand or changes in usage patterns, it triggers the need for more wind generation, battery storage, and costly long-duration backup such as hydrogen, substantially raising infrastructure requirements and costs.”

Delic and Bucksteeg also said that the effect brings regressive distributional implications. “The additional system costs are passed through to all electricity consumers via higher prices, disproportionately affecting households that cannot afford to install a PV system,” they explained.

An accompanying policy brief to the research calls on policymakers to incorporate the solar rebound effect into official system planning, in order to ensure energy infrastructure is designed for realistic demand. It also emphasizes that the effect should not be treated as a fixed increase in demand, as it timing varies across hours and seasons and therefore can substantially change infrastructure needs, system costs and planning outcomes.

Delic and Bucksteeg aslo explained that under binding emissions cap and climate targets, additional demand caused by the solar rebound effect must be met by renewable energy sources.

“Whether this implies more solar or wind capacity depends on the timing of the rebound effect,” they said. “The associated increase in flexibility needs requires additional battery storage, although more flexible demand can help limit this requirement. At the same time, higher peak loads, for example due to increased use of air conditioning in summer-peaking systems, may raise the need for backup capacity, provided in the short term by natural gas and in the long term by renewable hydrogen.”

The pair also stressed that meeting additional demand does not simply mean building more generation capacity.

“The least-cost strategy depends critically on when that demand occurs. The first priority should therefore be demand-side policy with incentives that encourage households to shift flexible consumption to sunny hours,” they explained. “If policymakers succeed in steering consumption toward periods of high solar output, for example through dynamic feed-in remuneration schemes or by requiring dynamic electricity tariffs for PV households, the system can absorb much of the additional demand with relatively small infrastructure adjustments.”

Delic and Bucksteeg also suggested that expanding grid infrastructure and enhancing cross-border market integration can help accommodate the additional flexibility requirements induced by the solar rebound effect. “By enabling the spatial balancing of renewable generation and demand, a more interconnected system reduces reliance on local storage and backup capacity, thereby limiting overall system costs,” they said.

Their findings are presented in the research paper “Implications of the solar rebound effect for the European energy transition,” available in the journal Nature Energy.

Previous research on the solar rebound effect from Australia and Vietnam found the phenomenon could happen in any country where the policy supporting solar is not fully and scientifically explained. Last year, researchers from Switzerland’s University of Bern found that the installation of a residential rooftop PV system could increase a household’s power consumption by up to 11%.