Matching electrochemical CO2 reduction with fluctuating photovoltaic power under natural illumination

Abstract

Photovoltaic (PV)-driven electrocatalytic CO₂ reduction enables solar energy storage and green fuel production, but PV fluctuations cause instability, impacting product selectivity and system stability. To tackle this challenge, we propose a novel control strategy that dynamically adjusts the number of operating electrolytic cells. This approach enables real-time matching of PV output with the electrolysis system, stabilizing voltage and current input. The performance of PV modules and electrolyzers was evaluated individually, with results integrated into a simulation model to predict system behavior. Additionally, an outdoor experimental setup was constructed to validate the design under real-world conditions. The system demonstrated the ability to dynamically adjust the number of operating electrolyzers from zero to four in response to fluctuating PV power. Compared to an uncontrolled system with a current density variability of 150 ± 90 mA cm⁻², the proposed control strategy stabilized the current density to 210 ± 40 mA cm⁻², highlighting its effectiveness in managing fluctuating power inputs.