Design of Homemade Soiling Station to Explore Soiling loss effects on PV Module /

Abstract

Solar Photo-Voltaic modules installed outdoor are exposed to different environmental factors like soiling and humidity which affect their performance. Due to soiling on Photovoltaic module, the active area of Module reduces that causes loss in short circuit current (Isc) of Photovoltaic Module due to the loss in light transmittance. Soiling loss studies conducted in outdoor conditions are unreliable as environmental factors are uncontrolled and vary with time. This study reports an indoor soiling station with cost reduction, design improvements, and automation that has been designed to stimulate the soiling effects to study the effects of environmental parameters influencing soiling on Photovoltaic Modules under desired and controlled conditions. The proposed soiling station is capable to explore optimized soiling loss effects on PV modules by varying tilt angle, humidity, wind speed, and temperature. The soiling uniformity in the soiling chamber was found to be uniform throughout with a standard deviation of 0.07%. A homemade soiling station was used to simulate the daily outdoor soil cycle and series of experiments were carried out to investigate the effect of tilt angle, humidity, and wind speed on the soil deposition process and consequently the effect on PV Module performance. The temperature range kept for all the experiments was from 10 ⁰C to 70 ⁰C while the humidity was varied from 50% to 80% with an interval of 15%. Similarly, tilt angle was varied from 0⁰ to 33.6⁰ (latitude of Islamabad) and finally to 65⁰. The effect of wind on soiling was studied in the wind tunnel. Wind speed was varied from 2m/s to 4m/s and then 6m/s. The results of the experiment showed that increasing humidity results in increased soiling loss as at higher humidity soil sticks firmly to the PV module glass surface. Increasing the tilt angle caused the soil to settle on the PV module surface less firmly. Higher tilt angle also produced self-cleaning patterns in the PV module surface. After soil deposition at different relative humidity levels, the PV module was exposed to different wind speeds using a wind tunnel and it was found that at higher wind speeds, power gain due to wind was higher. Contrary, at higher humidities soil settled on the module surface firmly and wind gain at 85% humidity was comparatively very low even at higher wind speeds. This Soiling station can be used to test the performance of different anti-soiling coatings and lab-scale solar cells at different environmental factors. In addition, efficiency, as well as the economics of cleaning processes and feasibility of better solar installation sites, can be investigated.