By the time this piece reaches you, the notion that heat is the enemy of solar efficiency may be due for reconsideration; specifically when it comes to solar-plus-storage systems based on photoelectrochemical (PEC) flow cells.
But in a recent experimental study led by Olaya Salvado-Recarey and Dowon Bae from Loughborough University, published in The Journal of Chemical Physics, a different story emerges for PEC redox flow cells. Here, heat can accelerate ion mobility and enhance electrolyte conductivity, increasing current density up to a certain temperature. Please see the published paper here:
Salvado-Recarey, O., & Bae, D. (2025). Temperature impact on thermo-electrochemical behavior of silicon-based photoelectrochemical flow cells. The Journal of Chemical Physics, 163(7). https://doi.org/10.1063/5.0283536
Conventional photovoltaic (PV) systems lose efficiency as temperature increases. Research shows that, for standard silicon modules, heat raises current yet reduces voltage, leading to a net performance drop; often around 0.3–0.5 % per °C above the 25 °C standard test condition.
Using a single-junction crystalline silicon (c-Si) photoelectrode in a classic Fe(CN)₆³⁻/⁴⁻ electrolyte, researchers ran voltammetry and impedance tests across a temperature range. With rising temperature, current density increased, driven by enhanced reaction kinetics and improved electrolyte characteristics—but potential output did dip slightly.
Notably, the benefits peaked around 45 °C, beyond which the gains plateaued or even slowed. That suggests there’s an operational sweet spot—warm enough to benefit from faster chemistry but not so hot as to trigger counterproductive effects.
Dr. Dowon Bae, of Loughborough University stated the following:
“Instead of fighting against the sun’s heat, our research shows we can harness it, It flips the conventional wisdom on its head and gives us a new way to design solar storage systems that thrive in hot conditions. So, instead of fighting against the heat, engineers can now use it to their advantage, creating more efficient solar energy storage solutions. By understanding and harnessing this hidden effect, we can ultimately make integrated solar technology a more viable option for powering our world.”
This finding invites a shift in how solar-storage devices are engineered. Rather than cooling these systems aggressively, designers might purposely allow—or even target—operation in warmer conditions to simplify systems and lower costs. Applications in hot climates could be more economical without conventional thermal management.
This isn’t the only instance where integrating heat strategically makes sense. Photovoltaic-thermal (PVT) hybrid collectors, which harness both electricity and usable heat, improve overall conversion by cooling PV cells while capturing thermal energy for secondary use.
In that approach, waste heat boosts system efficiency. The PEC flow cell finding complements this logic: here, heat is not waste but assistance to chemical storage processes.
- Material and electrolyte choice: Can other designs or chemistries push the temperature sweet spot higher, or buffer the saturation point?
- Integrated design: How might storage modules be coupled with PV or thermal collectors to balance temperature and efficiency?
- Field validation: Laboratory setups show promise—but real-world variations (sunlight cycles, ambient conditions, long-term stability) need testing.
Hassan graduated with a Master’s degree in Chemical Engineering from the University of Chester (UK). He currently works as a design engineering consultant for one of the largest engineering firms in the world along with being an associate member of the Institute of Chemical Engineers (IChemE).
