Assessment of Mixed Energy Storage System Considering High Spatial Resolution Data from a Real PV Installation

This paper focuses on improving instability issues in typical residential PV micro installation operation. Based on the high-resolution long-term recording of the power fluctuation in residential photovoltaic installations located in Tallinn, Estonia, different instability problems are identified and addressed. A mixed energy storage system (ESS) was considered for rapid and effective compensation of the detected fluctuations. A hybrid supercapacitor and battery based system was proposed to mitigate the actual problems in PV generation and balance the system operation. A 32 Wh supercapacitor bank coupled to the DC link of the PV inverter was proposed to mitigate the short-term and long-term power fluctuations on the generation side. Peaks and dips in the consumption and generation were identified using the Z-score-based peak detection method. The experimental results from different ESS sizes were compared and discussed. Moreover, several instances of generation fluctuations were mitigated by utilizing the supercapacitor bank.