Demonstration of green hydrogen production using solar energy at 28% efficiency and evaluation of its economic viability

Abstract

The solar to hydrogen (STH) efficiency of photovoltaic-electrolysis (PV-E) setups is a key parameter to lower the cost of green hydrogen produced. Commercial c-Si solar cells have neared saturation with respect to their efficiency, which warrants the need to look at alternative technologies. In this work, we report a concentrator photovoltaic-electrolysis (CPV-E) setup with a STH efficiency of 28% at 41 suns (without the use of Fresnel lenses), the highest reported efficiency using an alkaline system to date. Using this as a base case, we carried out a detailed techno-economic (TEA) analysis, which showed that despite the high cost associated with CPV cells, the levelized cost of hydrogen (LCOH) is at $5.9 kg⁻¹, close to that from c-Si solar farms ($4.9 kg⁻¹), primarily due to the high STH efficiency. We also report sensitivity analysis of factors affecting both CPV and alkaline electrolyser systems such as the CPV module efficiency and installed capacity, electrolyser stack lifetime, operating current density, and working hours. Our results indicate that in a scenario where the installed capacity of CPV technology matches that of silicon and with an electrolyser operating current density of ∼0.7 A cm⁻², the LCOH from CPV-electrolysis systems can be <$2 kg⁻¹. These results demonstrate the potential of CPV technology for large-scale green hydrogen production to replace that obtained from fossil fuels.