Experimental analysis of a vanadium redox flow battery stack under real renewable profiles for self-consumption and grid-support studies

This study presents a comprehensive experimental and theoretical analysis of a six-cell Vanadium Redox Flow Battery (VRFB) stack. The system was characterized using linear sweep voltammetry and charge–discharge cycles at different current densities to determine key operational parameters, including the state of charge (SOC), and to establish the correlation between theoretical and experimental SOC values. A current density close to 60–80 mA cm⁻² was identified as optimal, achieving a compromise between current and energy efficiencies (93 % and 75 %, respectively). To evaluate performance under representative operating conditions, the battery was subjected to variable charging and discharging profiles derived from real renewable patterns (solar and wind energy). Under these conditions, the VRFB exhibited improved operation compared to constant current operation, achieving an energy efficiency up to 80 %. Finally, two real consumption scenarios were analyzed: self-consumption with variable discharge and grid-coupled operation for frequency regulation. Based on the results, this work proposes a methodology for dimensioning VRFB systems for representative scenarios, demonstrating the battery’s operational flexibility and effectiveness in renewable energy integration and smart grid support. Moreover, analyzing real profiles in different scenarios provides valuable insight into defining optimized operating strategies for representative applications where managing charging and discharging fluctuations is essential.