A Novel Overall Efficiency Index for a Single Phase Standalone Solar PV Hybrid Inverters

The paper examines the performance of battery charging and power efficiency on 8 Nos. of two-stage standalone solar photovoltaic-based single-phase hybrid (solar-battery) inverters. A novel parameter called the overall efficiency index (OEI) is defined for measuring the overall efficiency of standalone solar PV inverters. This article examines the performance of these inverters in terms of their battery charging efficiency, energy conversion efficiency, and determination of the Overall Efficiency Index (OEI). The Maximum Power Point Tracking (MPPT) efficiencies are over 99%, the battery charging efficiency (BCE) value is highest at 3 kW at 96.56%, and the power conversion efficiency (PCE) value at 2 kW is highest at 90.19%. The OEI value does not depend on the nominal power of the inverter and, at 86.59% or 75.67%, is highest for 2 kW inverters and lowest for 1 kW inverters. Experimental results show that the OEI value shows better judgment of the overall performance of the standalone inverters. Choosing the right solar power system design and inverter is crucial, and MPPT and BCE play an important role in this process. Additionally, understanding the key factors that affect PCE is essential for ensuring optimal inverter performance. Finally, this method offers potential techno-economic benefits to a wide range of users.