Possible renewable energy plan?

If the US is really interested in investing in renewable energy, why are we focused on developing possible energy sources instead of harnessing an already existing energy source…the sun. Wouldn’t it make sense to use all that “development” money to equip all or most buildings (residential and commercial) with the means to be solar powered? Since the sun is free, it would be a one-time investment that would pay off for many years to come. Since the sun is free, would the powers-that-be ever allow such a thing to happen?