The dust deposition on top of solar panels blocks the solar insolation, causes erosion of the solar panel surface material, andalso deviates the maximum power point of the solar panels’ power output, which results in reductions of the panels’ poweroutputs and accelerations on the panels’ aging process. In practice, periodically cleaning efforts on the solar panels have to beconducted for dust removal, which intensifies the operational cost of many solar photovoltaic power plants. This study proposesan optimal cleaning plan for the PV plants that are prone to the dust deposition. In order to obtain the optimal cleaning plan,we first investigate the dust deposition process and develop a model to describe how PV power generation varies with thenon-uniform dust deposition patterns. Then we formulate a constrained optimization model to identify the most cost-effectivesolar panel cleaning strategy. In the optimisation, the additional revenue due to cleaning the solar panels is formulated as theobjective function. The decision variables are the number of PV strings to be cleaned at each cleaning interval. A case study ispresented to show how effective the proposed optimal solar panel cleaning strategy is.