A novel cleaning technique is proposed in this research, which suggests installing the electrodes of the electrostatic cleaning system on the backside of the PV panel in order to avoid the shading caused by the interference with the sun light reaching the panel. The influence of installing the electrodes on the backside of a glass plate on removing the dust from the front side is examined experimentally, as a function of the glass plate thickness and the material of the back cover of the electrodes. The materials used for the back cover of the electrodes are wood, glass and air, such that the electrodes are sandwiched between the glass plate and the cover. The glass plate mimics a PV panel. The experimental setup depends on two techniques to measure the diffusivity of the electric field on a glass plate and a PV panel as a function of the glass plate thickness and the back cover material. The first technique utilizes an ultra-sensitive electric field sensor based on the Whispering Gallery Modes (WGM), while the second technique is based on visual observation of the excitation voltage required to remove the dust from the glass surface. It has been found that the strength of the electric field above the glass plate and the PV panel in case of using wood as a back cover is higher than that for air and glass back covers. It can be concluded that wood resists the diffusivity of the electric field from the backside of the panel more than air and glass. Also, it has been found that the excitation voltage of the electrostatic cleaning system is proportional to the thickness of the glass plate and adding a wooden cover on the electrodes decreases the excitation voltage, in comparison to the cases of no cover or a glass cover.