The invention relates to a method including spraying steam in the form of multiple jets with a pressure and a temperature depending on the characteristics of the solar panel to be cleaned and of the impurities to be removed and at an angle that can be adjusted relative to the panel. The method can be combined with gentle cleaning using elements contacting the surface of the panels to be cleaned. The device includes a self-propelled vehicle, a water tank feeding a system for treating and purifying the water prior to feeding a steam generator, with a means for regulating the output temperature and pressure of the steam, which enters a system for distribution to the steam diffusers, which are coupled on a support associated with a cantilevered structure of the self-propelled vehicle.