Optimization strategy for high efficiency 20?kW-class direct coupled photovoltaic-electrolyzer system based on experiment data

摘要： For the first time worldwide, the PEM electrolyzer directly coupled with the up-to-20 kW PV panels to produce hydrogen is reported as a demonstration of a high solar-to-hydrogen (STH) efficiency CO2-free hydrogen-production system. With the direct-coupling configuration, the power loss on an interlink DC/DC converter and its cost are avoided as known. Since the maximum power point (MPP) of PV unit is fluctuated by the fluctuating irradiance, this MPP is tracked by changing the number of the electrolyzer cell controlled by the MPPT algorithm, which allows changing the PV operating voltage. In our system, the averaged PV efficiency is 17.2%, and the electrolysis efficiency is 86.5% in a whole-day test. Thus, the STH efficiency is 14.9%. The hydrogen generation capacity of 18.6 Nm3 (5.01 kg CO2 reduction) is demonstrated in that whole-day test. Besides, the method to make the simulation model of the system from on-site data is shown. As a result, neither the preliminary test nor off-site test is needed. Therefore, this method can be used to check the condition of the entire system and each component in long-term operation which has never been found in the literature. The simulated model can also be used to investigate the PV-electrolyzer system.