Research from the German FernUniversität Hagen shows that the rebound effect of solar energy, caused by households increasing their total electricity consumption after installing a solar system, is currently a blind stop in the planning and reduction scenarios of the European energy system.
The rebound effect of solar energy, which occurs when the adoption of rooftop solar increases household electricity consumption, could cause additional system costs of up to €23.5 billion ($27.6 billion) per year in Europe, new research shows.
Mensur Delic and Michael Bucksteeg, from FernUniversität in Hagen, Germany, studied the role of the phenomenon within the European energy system by integrating different intensities of the sun’s rebound effect into an open-source optimization model of the European energy system.
The research shows that the rebound effect of the sun could increase electricity demand by 63 TWh to 314 TWh in 2050, increasing total demand in Europe by as much as 5.1% in the worst case. This additional demand would require additional renewable energy generation and network flexibility, which could increase the total cost of the energy system by €6.7 billion to €23.5 billion per year between 2030 and 2050.
Delic and Bucksteeg told them pv magazine Their work highlighted that the solar rebound effect is currently not taken into account in official energy system planning and reduction scenarios, leaving a significant blind spot. The pair added that it is not only the size of the recovery that matters, but also its timing.
“If households consume additional electricity during sunny hours, the system can meet this demand at relatively low cost,” they explained. “However, as rebound consumption shifts to evening or winter periods, driven by higher baseline demand or changes in usage patterns, this creates a need for more wind energy, battery storage and costly long-term backup such as hydrogen, significantly increasing infrastructure demands and costs.”
Delic and Bucksteeg also said that the effect carries regressive distributive implications. “The additional system costs are passed on to all electricity consumers through higher prices, disproportionately affecting households that cannot afford to install a PV system,” they explained.
An accompanying policy brief to the study calls on policymakers to include the solar revival effect in official system planning, to ensure energy infrastructure is designed for realistic demand. It also emphasizes that the impact should not be considered as a fixed increase in demand, as the timing varies hourly and seasonally and can therefore substantially change infrastructure needs, system costs and planning outcomes.
Delic and Bucksteeg also explained that under binding emissions caps and climate targets, the additional demand caused by the solar revival 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 need. At the same time, higher peak loads, for example due to the increased use of air conditioning in summer peak systems, may increase the need for backup capacity, provided in the short term by natural gas and in the long term by renewable hydrogen.”
The pair also emphasized that meeting the 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 policies with incentives that encourage households to shift flexible consumption to sunny hours,” they explained. “If policymakers manage to steer consumption towards periods of high solar output, for example through dynamic feed-in reimbursement schemes or by requiring dynamic electricity tariffs for PV households, the system can absorb a large part of the additional demand with relatively minor adjustments to the infrastructure.”
Delic and Bucksteeg also suggested this Expanding grid infrastructure and improving cross-border market integration can help meet the additional flexibility requirements caused 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, reducing overall system costs,” they say.
Their findings are presented in the research paper “Implications of the solar rebound effect for the European energy transition”, available in the magazine nature energy.
Previous research into the rebound effect of the sun in Australia and Vietnam has shown that this phenomenon is possible happen in any country where policies supporting solar energy have not been fully and scientifically explained. Last year rResearchers from Switzerland’s University of Bern found that installing a PV system on the roof of a home could increase a household’s energy consumption by up to 11%.
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