The March 2007 issue of Physics Today has an article on "Solar Energy Conversion" by George Crabtree of Argonne and Nathan Lewis of CalTech  (free: HTML, PDF). Abundant, versitle and clean, solar electricity contributes a miniscule 0.015% of the world’s total electricity production, mostly because solar energy remains too expensive. Wouldn’t it be great if we could figure otu a way (or ways) to make soler energy more available and less expensive? Crabtree and Lewis discuss a range of options to develop solar energy based largely on ideas in a US Department of Energy workshop report.
One scheme would concentrate solar radiation to generate high temperatures which can then be converted to electricity using thermoelectric technology. (Well, strictly speaking the heat is converted to electricity, not the temperatures, but I digress). And, of course, this will require thermoelectric materials and devices much more effiicient and less expesnsive than available today.
A recommended read for anyone interested in thermoelectrics.