The size of a typical residential solar panel today is about 18 square feet, or a little less than 3-1/2′ x 5-1/2′. They’ll vary in size, depending mostly on the rated wattage and technology of a particular product’s solar cells. Most residential solar panels installed today are in the 185-240 watt range and are usually assembled with either polycrystalline or monocrystalline silicon cells.
For example, the popular Sharp 235w monocrystalline module measures 39.1″ x 64.6″ or about 17.5 square feet. So for a typical system in the 5,000 watt range, you would need approximately 400 s.f. of available space.