Electrochemical CO₂ reduction reaction (eCO₂RR) offers a promising pathway toward a circular economy by converting CO₂ into value-added products such as formate, carbon monoxide, and ethanol. Among the products, formate has gained particular attention as a versatile C₁ building block. Pilot-scale demonstrations have reached kilogram-scale CO₂ conversion per day using large-area electrodes. Thus, the sustainability of this highly electricity-intensive process critically depends on its integration into the renewable energy landscape. Foremost battery storage is required to ensure continuous operation of eCO₂RR while utilizing solar power and addressing its variability. In this study, we developed and applied a tailored photovoltaic (PV) system with battery storage to evaluate long-term renewable energy supply for eCO₂RR at different scales (10 cm²–300 cm² Sn–GDE setups), using the UFZ location in Leipzig, Germany, as a reference site. For developing such a stand-alone power supply at the reference site, PV power generation data obtained using the Renewable Spatial–Temporal Electricity Production (ReSTEP) simulation model, which is based on real weather data, were combined with experimentally derived energy demands of the eCO₂RR setups at different scales. As a result, the required number of PV panels and batteries for reliable year-round operation was determined. The results show that the number of solar modules scales proportionally with the electrode size, while sufficient battery storage is essential to buffer up to three consecutive days without sunlight and maintain safe discharge limits. For the 100 cm² setup, additional off-grid simulations demonstrate that increasing the battery capacity improves both system reliability and battery lifespan. Overall, this study demonstrates that tailored PV systems with battery buffering can enable sustainable operation of eCO₂RR from laboratory to pilot scales, highlighting a practical route for integrating this technology into future electrobiorefineries and advancing its readiness toward industrial deployment.