The present invention relates to a photovoltaic device, a solar panel is the solar power generation portion and arranged to be inclined disposed to be a predetermined height spaced apart on top of the solar panel glass sheet and of the solar panel the height is arranged on the high side, and the water supply unit for supplying water to the surface of the solar panel the height of the solar panel is arranged in the lower other end, on which the solar panel and the salt crystals produced by the contact of the sea water collecting salt collection tube and is provided at a side of the water supply section, it moves from the lower along the spaced space between the solar panel and the glass plate to the top, and a heat exchanger for generating fresh water condenses the air containing the water vapor evaporated from the water included, and the heat exchange unit, deep water to push the deep waters from the deep-sea supply line deep-sea water supply pumps to ensure that the number of deepwater supply of deep water feed pipe deep water not deep the deep supplied from the supply pipe stored in a storage tank deep can the storage tank deep-sea feeding the admission that deepwater number of inputs and the deep-sea feeding Immigration and deep water are placed apart discharge and a plurality of deep linking together the deep-sea feeding the admission and the number of deep discharge water heat pipes and nursing admission the deep and and accommodated inside the can discharge and be the deep-sea deep-sea heat exchange tubes, and an outer case formed the steam inlet which air flows containing the vapor on one side and wherein the water vapor condensed by heat transfer and the deep water heat exchanger tube and the fresh water tank is produced fresh water is stored is coupled to an upper portion of the outer case comprises an air discharge pipe for discharging air condensation is complete, to the outside, comprising: a water supply pump to push the water supply is seawater, the su
