Provided is a device and method of cleaning a solar panel of a solar boat using, as cleaning water, water externally introduced and compressed during operation of the solar boat. The device includes a water inlet port disposed on the front side of the solar boat, a filtration unit removing impurities from water introduced through the water inlet port during operation of the solar boat, a compression unit compressing impurities-removed water, and a spray nozzle spraying the compressed water to the solar panel.