Performance Analysis of an Off-Grid Solar Power Plant for Meeting Multi-Building Electricity Demands at Polytechnic State of Padang

Abstract

This study evaluates the operational performance and economic potential of an off-grid solar power plant (SPP) installed at the Polytechnic State of Padang’s AC lecture building. Analysing data from January to May 2025, the research identifies a significant energy surplus, with the system generating between 10.36 kW and 36.84 kW against a maximum weekday demand of 15.54 kW. Technical analysis reveals that peak power reached a maximum of 40,298 W in April, reflecting optimal solar irradiation, while peak production consistently occurred between 09:00 and 10:00. The integrated battery system demonstrated robust performance, with the monthly average State of Charge (SoC) increasing from 57.12% in January to 63.23% in May, indicating progressive energy management optimisation. Charging and discharging efficiencies remained high, peaking at 93.19% in April. Despite a production decline in March due to inconsistent sky conditions, the system maintained a high total energy yield, with February recording the highest output at 2,960.07 kWh. Economic analysis indicates that the surplus energy presents a substantial opportunity for cost reduction. By redistributing excess power to adjacent buildings, the total potential cost savings for the five-month period were calculated at IDR 19,298,045.18. These findings suggest that the current off-grid installation is significantly underutilised and could serve as a primary energy source for a micro-grid network within the campus, enhancing both technical efficiency and financial sustainability.