Off-Grid Solar Systems: An Experimental Work and Systematic Techno-Economic Analysis

This study presents an integrated experimental and techno-economic analysis of off-grid solar photovoltaic (PV) systems. A custom data-logging platform, developed using an ATmega328P microcontroller, was employed to monitor the performance of two 100 W mono-crystalline PV modules under real outdoor conditions in Zhenjiang, China, from April to August 2023. The logger continuously recorded voltage, current, solar radiation, and temperature with 20-second resolution, enabling evaluation of operational behavior. Results revealed a strong positive correlation between solar radiation and power output, while higher cell temperatures led to a notable decrease in efficiency. The maximum peak power of 69.55 W and 74.51 W was achieved on 11 July 2023, with the highest efficiencies of 14.65% and 15.98% observed on 15 June 2023. Economic assessments using net present value (NPV) and levelized cost of energy (LCOE) methods showed that a simple DC configuration remains cost-competitive with the grid (LCOE ≈ ¥0.38/kWh). However, its payback period exceeds 10 years. Conversely, the AC system, which required an inverter, was economically non-viable under current market conditions. These findings highlight the importance of minimalist design and provide a validated dataset for optimizing low-cost off-grid PV applications in similar climate zones.