Design a low-cost solar PV data logger and assess the application and accuracy with off-grid monocrystalline panels

Meteorological parameters significantly influence the photoelectric conversion efficiency of photovoltaic (PV) modules, playing a pivotal role in determining the overall system performance. This research aims to investigate the effects of these parameters on the electrical and thermal performance of off-grid monocrystalline PV panels using an innovative microcontroller-based data logger system. This study conducted an experimental investigation between April and August 2023 to monitor two off-grid PV systems of 100 watts with loads. The record outputs on July 11, 2023, with 69.55 W and 74.51 W for PV-1 and PV-2 modules, respectively, at an irradiance of 982.52 W/m², demonstrate a strong correlation between the PV output power and cell temperature. The best efficiencies reached were 14.65% (PV-1) and 15.98% (PV-2) on June 6, 2023, demonstrating a strong influence of thermal gradients on the performances. The fabricated data logger, based on an ATmega328P microcontroller, incorporates multi-point temperature measurement (5 sensors), triple data export (SD card, USB, and IoT), and real-time monitoring at 95-98% lower cost than commercial alternatives. The results indicated a power loss rise of 6.48-7.58 W/100 W/m² increase in irradiance, corresponding to a temperature sensitivity and efficiency loss of 2.59-2.82%/100 W/m², with a ±1–5% margin. The modularity indicates that the system is well-suited for rural electrification and small-scale off-grid installations. This work extends the capabilities of low-cost PV monitoring by bridging the gap in both spatial thermal resolution and cost, providing a platform for the development of optimized renewable energy interventions in low-resource environments.