A Feasibility Study on the Effect of Soiling on the Performance of Solar Pv Water Pumping Systems in Nairobi.

Abstract

Thesoiling effects on solar photovoltaic modules and solar water pumps areof great concern in countries with large generation potential for solar energy.Previous studiesindicate that soiling affects thePV performance. No previous studies on soiling impacts in Kenya as well as their influence on solar water pumping have been conducted. In this project, the cumulative effects of dust accumulation were investigated for a period of90 days. Two sites in Nairobi; Karen and industrial area were selected. The soiling impact affected key performance metrics and this wasused to conduct a comparative analysis between clean and soiled panels as well as modules at different tilt angles and location. The results indicate that cumulative soiling considerably reduced the power output of the soiled panel as compared to the cleaned one(12% reduction). Low tilt angle was also found to promotedust accumulation (11.9% less for module at 10).Soiling was found to reduce the efficiency of the module from 10.5 % to 7.26% (15tilt angle) and 6.3% (10tilt angle) for the first 25 days and this further reduced to 4% (15tilt angle ) and 4.22% (10tilt angle). Soiling losses were found to increase with cumulative dust adherence over the study period and were affected by the tilt angle. The fill factor was also affected by soiling. The cleaned module had a FF = 0.81 while the soiled module had FF= 0.70(13%less) in the first month and 0.52 (34.8%) in the last month. Soiling was also found to cause significant loss in rectangularity of the I-V curves and this increased with more dust accumulation. Dust accumulation was affected by the location. The industrial area site recorded lower power, efficiency and increased soiling losses as compared to the Karen site. The pump performance was found to reduce with increase in soiling over the entire study period. Dust accumulation significantly reduced flow rate and maximum head and altered the shape of performance curves (Q-H curves). It is recommended that a correction factor be introduced when designingand sizing PV panelsin Kenya and regular cleaningto reduce these effects.