Estimation of soiling losses in photovoltaic modules of different technologies through analytical methods

Photovoltaics (PV) has reached high level of maturity in terms of material efficiency and low production costs. For this reason, nowadays, lot of emphasis is put on the reduction of the operation and maintenance costs. Soiling is one of the issues that most affect these costs. So, the understanding of its electrical and economic implications is essential to optimize the cleaning routines and minimize the associated costs. This paper investigates the possibility of estimating soiling directly from PV performance data, without the need of installing specific soiling monitoring equipment, which typically needs careful and regular maintenance. Five analytical methods are evaluated and applied to the data of PV modules of different technologies (m-Si, CdTe and CIS). An experimental campaign is conducted in a location in Southern Spain with low-moderate levels of soiling. The methods show promising accuracies when used to obtain the soiling losses of a module, especially during soiling-intense and long dry periods.