Effect of tilt angle on soiling of photovoltaic modules

Soiling on PV modules is known to reduce PV system performance, mainly in dry arid climatic conditions. Cleaning with water or other means may become an expensive solution to the problem. For the highest annual energy production from a fixed tilt PV system, the modules are typically installed at tilt angle close to latitude angle of the system´s location. Soiling loss is an interplay between terrain of the installation, tilt angle, rain frequency and rain intensity. For un-cleaned arrays in certain dusty locations, it would be better to optimize the tilt angle for maximizing transmitted radiation to the cells by adjusting the tilt angle slightly higher which would in turn minimize the soiling loss. In this work, we have developed an inexpensive soiling station which evaluates soiling loss at different tilt angles (0°, 5°, 10°, 15°, 20°, 23°, 30°, 33°, 40°). For Mesa, Arizona (a hot-dry climate), the 0° tilt angle showed a 2.02% loss whereas 23° and 33° showed soiling loss close to 1% during the first three months of 2011.