New Solar Technology

Gallium Arsenide cells are already decades old a proven technology producing double the efficiency of silicon based cells. Downside is cost. Many spacecraft and satellites use them as cost is no object, but efficiency is paramount.

Seems to me this would be the best place to focus R&D on simply making GaAs multi-junction cells cheaper. These things are hitting close to 50% efficiency under focused light and in the 30's under one sun.