In a separate experiment, when a panel was not cleaned for two months in winter, the current output reduced to 30% of the values obtained from the cleaned panel. The reduced effect of dust during summer may be attributed to (a) higher wind speed (8 to 20 km/hr) and (b) the south-west direction of wind which makes larger surface of panel to come in contact with wind. Both the factors help in blowing away the dust from the panel.