Hybrid PV systems – Optimizing CPV and SiPV ratio to increase sustainability of hydrogen production

This paper establishes the concept of hybrid PV systems where the ratio of different photovoltaic (PV) technologies is optimized so that their combined output profile best matches user requirements. The method is presented and applied to a case study where a two-axis tracking concentrating photovoltaic (CPV) and a single-axis silicon photovoltaic (SiPV) system installed at a sub-tropical location in Australia, are to power the production of hydrogen by electrolysis. The analysis quantifies the performance of the PV systems from data gathered at the site and reveals the complementarity of these two systems in their output at different timescales. An optimization problem is then defined that seeks the optimal ratio of CPV and SiPV to achieve high annual power output and, importantly, a good match between power supply and demand profiles. The benefits of this approach are illustrated for a green hydrogen power-to-gas-to-power plant under two operating modes. For this case study, the optimal PV ratio of 0.33CPV: 0.67SiPV leads to reduced dependence on the electricity grid, and a maximum guaranteed minimal take-up of hydrogen over all months in a year. Overall, the sustainability of the plant is increased without the need for additional storage, and therefore additional resources.