Until you would have tremendous penetration of this technology, the solar energy would just be used to lower maximum energy requirements (during the day) of the grid. In AC intensive locations like the south, even cloudy days would not hurt, because the peak energy requirement would be lowered at the same time the solar energy would not be as available. I would think you could have as much as 25% of your energy supplemented by solar on sunny days without the need for storage.
Of course right now this is just a claim, but I don't think there is much doubt that solar energy prices are coming down as fossil fuel prices are going up and some point this alternative energy form will be truly viable on a mass scale (competitive in the real non-subsidized market).