Development of Solar-Powered System for Off-Grid Application

Many off-grid health facilities have no dependable electricity supply, and extending the national grid to low-density settlements is often too costly. This paper presents the design, sizing, and preliminary field testing of a stand-alone solar-powered system that supplies a small dispensary load through a pure sine wave hybrid inverter. A design load of 2.4 kW for 6 h per day was used to size a 4.32 kWp PV array (fifteen 300 W modules), a 24 V, 660 Ah battery bank (six 12 V, 220 Ah batteries), a 3.5 kVA inverter and a 70 A charge controller built around a PIC16F877A microcontroller. The scaled prototype of two monocrystalline panels, two 220 Ah batteries and the 3.5 kVA inverter was monitored for four days (15–18 December 2024) and compared with a PVsyst simulation of the same configuration. Panel voltage stayed between 33.8 V and 38.2 V, and the peak current was 7.34 A. The measured peak power was about 3 [unit] against 3.35 [unit] simulated, a difference of about 10%. The measured behaviour therefore followed the simulated one, although the four-day record and the scaled prototype limit how far the findings can be generalised. The work contributes a documented sizing procedure and a measured-versus-simulated comparison for a small off-grid load