Comparative Investigation of the I–V Characteristics of Photovoltaic Modules Under Varying Environmental Conditions

Abstract

The current–voltage (I–V) characteristics and performance of monocrystalline and polycrystalline photovoltaic (PV) modules under varying environmental conditions across selected locations in Nigeria was investigated. The study aimed to evaluate the electrical performance of both PV technologies under different climatic conditions. Experimental measurements were conducted using monocrystalline and polycrystalline solar panels, a solar power meter for irradiance, a thermo-hygrometer for ambient temperature and relative humidity, an anemometer for wind speed, and an MPPT solar meter for voltage, current, and output power measurements. Data were collected under outdoor conditions at regular intervals during daylight hours. Performance was assessed using I–V characteristics for both panels, open-circuit voltage, short-circuit current, and power response were all obtained. The results revealed significant variations in PV performance across the selected locations. Monocrystalline modules consistently outperformed polycrystalline modules, recording higher current outputs of approximately 2.8–3.5 A and voltage values between 17.0 and 18.5 V under peak irradiance, whereas polycrystalline modules produced currents of about 2.3–3.0 A within similar voltage ranges. Locations with higher solar irradiance and moderate atmospheric conditions exhibited improved photovoltaic performance, characterized by smoother and more stable I–V curves. In contrast, lower irradiance and cloud cover reduced output current and overall efficiency. Elevated panel temperatures caused slight reductions in voltage due to the thermal behaviour of semiconductor junctions. Comparative analysis showed that increased irradiance enhanced photocurrent generation, while excessive temperature adversely affected voltage performance. Overall, monocrystalline PV modules demonstrated superior operational stability, efficiency, and electrical response under varying environmental conditions. The study concludes that photovoltaic performance in Nigeria is strongly influenced by local climatic conditions and semiconductor material properties, with monocrystalline modules offering greater suitability for outdoor solar energy applications in tropical environments.