<p>The solar rebound effect (SRE) occurs when rooftop photovoltaic adoption increases household electricity consumption, driven by the perception of solar energy as a free resource. Although empirically observed, the SRE has not yet been accounted for in energy system modelling or abatement scenarios. This study integrates empirically derived SRE intensities into an open-source optimization model of the European energy system, translating behavioural effects into temporally distinct demand profiles. The results show that not only the magnitude but also the timing of the rebound determines its system impact. Additional demand leads to increases in renewable investment needs, flexibility requirements and overall system costs while inducing regressive effects, as households driving the rebound do not bear its full costs. The findings call for explicit inclusion of SRE in abatement scenarios and grid planning and highlight load-shifting incentives and energy efficiency policies as key tools to mitigate rebound effects and align demand with renewable generation.</p>