Experimental Investigation On A Solar/Hydrogen-Based Microgrid

In this paper an experimental investigation on the performance of an integrated microgrid, installed at the laboratory of the University of Bologna, is presented. The integrated microgrid is made up of two photovoltaic solar panels, two batteries as electricity storage device, a hydrogen generator and an electronic load emulator. The direct current generated by the solar modules charges the batteries by means of a load regulator unit. The power electronics, including an inverter and a DC converter, provide the user with 12 V DC and 230 V AC to feed the electronic load and hydrogen generator, respectively. The aim of this experimental activity is to investigate batteries charging/discharging process and, as a consequence, to quantify batteries roundtrip efficiency value. Experimental trend of voltage, current and power input/output from batteries are observed during charging/discharging operation. Results of the experimental activity show that during the charging process, the voltage from the solar array tapers according to the batteries conditions and recharging needs, thus increasing the charge acceptance of the battery. Once batteries are about to reach full charged condition, the controller starts to hold constant voltage and reduce the charging current to avoid overcharging. Taking advantage of experimental activity results, average value of batteries roundtrip efficiency is determined.