The evaluation of the efficiency depends on several parameters to ensure that the production gain will cover at least the cleaning costs: (i) the modules cleaning costs, (ii) the capacity of the plant, (iii) the production yield, (iv) the Feed-in Tariff and of course, (v) the soiling rate. A recent study [1] presented a formula to express the frequency of cleaning to obtain a financial benefit.
For example, a plant of 100 kWp capacity, a production yield of 1200 kWh/kWp/year, a FiT of 0.11 €/kWh, cleaning costs of 360 € and an annual soiling rate of 1%, the optimal frequency would be to clean it every 2.3 years.
[1] Mohammad Abu-Naser; Electrical Engineering Department, Philadelphia University, Amman, Jordan ; “Solar Panels Cleaning Frequency for Maximum Financial Profit” ; Open Journal of Energy Efficiency, June 2017
By David Roisse, Asset Manager