Photovoltaic soiling loss in Europe: Geographical distribution and cleaning recommendations

Despite being one of the major issues that photovoltaic systems face worldwide, estimating the energy and economic magnitude of soiling of solar collectors still represents a challenge. This work presents a first European assessment of the soiling loss and of the cost-effectiveness of soiling mitigation. New soiling maps are generated through the interpolation of reanalysis data, calibrated against ground-measured losses from sensors installed across the continent. The results show that Europe experiences an average annual soiling loss of 0.9 % if rain is considered a perfect cleaning agent. However, if a cleaning effectivity by rain of 10 % is assumed, this annual loss increases up to 5.3 %. In some southern locations, soiling losses are markedly seasonal, while these are more consistent in central Europe. These losses can have repercussions on the economics of photovoltaics, increasing the levelized cost of electricity up to 4 % or 15 % depending on the cleaning effectivity of rain. The losses are also found to vary significantly in some sites from year to year, highlighting the need for continuous monitoring. The study concludes that implementing adequate soiling mitigation measures is strongly recommended in most of the regions due to the high electricity prices and the comparatively low cleaning costs.