Parallel Electrical Integration of Photo Bio Electrochemical Systems (photo‐BESs): Performance Gains and Load Dependency

ABSTRACT Bioelectrochemical systems (BESs), including biophotovoltaics (BPVs) and plant microbial fuel cells (PMFCs), represent an underexplored sustainable source of electricity. However, their power output is generally limited compared to conventional, non‐biological technologies. This study investigates the electrical performance of hybrid systems where a BPV is connected in parallel with a photovoltaic (PV) device, and a PMFC is connected in parallel with a direct current generator (CG). We demonstrate that under specific load conditions, these parallel configurations produce higher power or current outputs than the sum of the individual components operating independently—a phenomenon we define as superadditivity. In the BPV‐PV system, power gains reached up to 50% at a given external load, with statistically significant improvements under low external loads. The PMFC‐CG system also exhibited a superadditive trend, with a 34% increase in peak current output, though not statistically significant. We propose that the superadditive effect arises from reduced internal resistance and perhaps also metabolic stimulation of the biological components when integrated with physicochemical sources in parallel. These findings provide empirical evidence consistent with prior work and supportive of a superadditivity effect in parallel BES–PV/CG systems and offer promising insights for the development of hybrid renewable energy technologies.