Impact of tilt angle, dust deposition, and humidity on potential induced degradation and electrical performance of crystalline silicon photovoltaic modules: an experimental study

Introduction. Photovoltaic (PV) modules constitute the backbone of renewable energy systems, yet their performance is compromised by degradation mechanisms, particularly potential induced degradation (PID), which causes rapid power losses through ionic migration under high voltage stress, creating parasitic shunts that reduce shunt resistance Rsh and energy output. Problem. Although the influence of moisture and temperature has been widely investigated, the combined contribution of operational and environmental factors such as dust soiling remains insufficiently clarified. Goal. This work assesses dust as a contributor to potential induced degradation focusing on the combined effects of tilt angle, dust exposure and dust-moisture interaction on insulation integrity and degradation susceptibility. Methodology. A comparative experimental study was conducted on 3 identical crystalline-silicon PV modules without bypass diodes, installed at tilt angles of 20°, 30° and 40°. A controlled and uniform layer of sandy dust (maximum particle size about 150 μm) was deposited on the front surface. Insulation resistance between the frame and the front glass was measured at three locations (bottom, middle and top) under dry conditions and then at relative humidity above 80 %. The modules were subsequently subjected to a DC electrical stress of 1 kV, followed by cleaning. Electrical performance was evaluated under identical irradiance and temperature conditions using current-voltage (I-V) and power-voltage (P-V) characterization to extract the fill factor (FF) and Rsh. Results. Lower tilt angles (20°) promoted non-uniform dust accumulation, reducing insulation resistance and increasing leakage currents. High humidity intensified these effects, creating localized PID-prone regions. Post-cleaning, modules at 20° exhibited significantly lower FF and Rsh compared to 40°, indicating persistent degradation and incomplete recovery. Scientific novelty. This work establishes dust as an active PID initiator rather than merely an optical attenuator, uniquely examining coupled effects of tilt angle and dust-moisture interaction on PID susceptibility through moisture-assisted surface conduction pathways. Practical value. Appropriate tilt-angle selection and cleaning strategies are essential to preserve insulation integrity, limit leakage currents, mitigate degradation risk and maintain PV performance in dusty and humid environments. References 38, tables 6, figures 19.