Efficiency evaluation of photovoltaic systems with batteries considering different voltage levels

Abstract

The incorporation of batteries into photovoltaic (PV) self-consumption systems in buildings has a high potential to improve the degree of decarbonization and consumer benefits. However, very few studies have addressed the evaluation and comparison of the energy performance of PV systems with storage for self-consumption in buildings. Furthermore, studies have omitted the influence of energy storage at different voltage levels, which is an important parameter in the development of High Voltage (HV) lithium batteries.

Thus, a load control system was designed and connected to the output of two self-consumption PV systems with batteries operating at different voltages, to compare the energy efficiency under the same energy demand conditions and with identical solar irradiation levels.

The results show the importance of considering the voltage level parameter, as the average energy efficiency of High Voltage Installation (HVI) was higher than that of Low Voltage Installation (LVI) by 3 % to 10 % over the range of load powers analysed. Furthermore, it is shown that the most significant energy losses were influenced by the inverter's energy conversion process. Therefore, to achieve good system optimization, manufacturers should decrease the losses in this process and ensure high energy efficiency in the operating voltage and power ranges.