Typically solar installations cost approximately $9-10 dollars per watt in a turnkey system. So a 3kW (3,000W) system might cost $27,000-$30,000 before rebates. HOWEVER, federal, state, and local rebates can bring the price down considerably, and in some locations, magnificently. The size of the solar system that you need will depend mostly on how much electricity you use, as well as a long list of other criteria that an installer or sales professional will evaluate. Tilt, orientation, and shading of your roof are examples of some of these. As this technology becomes more available and more solar business companies are opening up around the globe, the price for this technology will become more cheaper and affordable.