Determining the Effect of Soiling and Dirt Particles at Various Tilt Angles of Photovoltaic Modules

Photovoltaic modules (PV) are the future of renewable energy production market. They provide green energy with no carbon signature. However there exists factors which degrades the performance of PV modules. Over time, sand and dirt particles are accumulated on the surface of modules which effects its performance. Similarly little amount of field data exists about the PV plants to predict its behavior. Generally the photovoltaic modules are mounted at a fixed tilt angle which is near to the latitude of the location in order to get maximum output energy. Soiling loss effects the output power of solar modules to a great degree. It has a relationship with the terrain, and the climate behavior of the location, the tilt angle of the modules and the frequency of rain at the installation site. For un-cleaned modules, adjusting the tilt angle would result in increase in the output energy. In this research we have developed a cheap solution for monitoring the soiling losses at different tilt angles. The selection of 33.5o was done because it is the latitude of the experimental area (Peshawar) where the test results were collected, because a general thumb rule is to install the photovoltaic modules according the latitude of the installation location. Furthermore instead of using huge photovoltaic modules small scale mini-modules were used for this study and their respective power ratings and dimensions are also described in detail. These mini modules were highly accurate and sensitive since a small amount of error would result in in-accurate data. The data was collected on regular basis from the mini-modules which were installed at different tilt angles. For each tilt angle two similar mini-modules were mounted, one was cleaned regularly while the other was left out un-cleaned for the entire period of study. In addition the irradiance data was also collected. In the end of the experiment the horizontal mini-module installed showed larger losses as compared to the other mini-modules.