As they get more and more efficient at Solar Thermal technology, any other source of power will be eclipsed by this technology. I can see this move on to the rooftops and displace Natural Gas for solar Hot water, as the water can stay hot enough overnight for morning showers.
http://cleantechnica.com/2012/04/08/halotechnics-molten-glass-thermal-storage-could-mean-6-cent-solar/
