Soiling and value of cleaning for low-tilt PV systems in temperate climates: A Swiss case study

Low-tilt PV systems are increasingly common on flat roofs, where they enable a high power density. Yet there little is known about their requirements in terms of operations and maintenance, especially soiling. Here we present a case study on a 410 kWp system in Switzerland with a 5° tilt. Nineteen months of inverter data have been carefully analysed and correlated with consolidated weather data from four weather stations. Unlike systems on sloped roofs, which are deemed self-cleaning in Europe, this system demonstrates a clear and lasting benefit from active cleaning, with a 6% gain in energy yield.