I'm wondering about the possibility of an etalon designed specifically to improve the efficiency of solar panels. According to http://www.oregon.gov/ODOT/HWY/OIPP/docs/solar_glarepotentialwl.pdf, a mono-crystalline silicon solar cell, similar to those used at the Solar Highway Demonstration site, absorbs two-thirds of the sunlight reaching the panel’s surface. That means that one-third of it is reflected back into the atmosphere, and thus, wasted.
If an etalon was designed consisting of two curved solar panels facing each other, set at just the right angle such that all the rays reflected from one of the panels go directly into the other panel (and vice-versa), there would theoretically be no loss. The amount of rays present inside the etalon (speaking very loosely) will decrease by two-thirds upon every subsequent hit on each of the solar panels. It's easy to see that this series would quickly converge to 0, thus making use of virtually all the sunlight that enters the etalon.
All this being said, I'm not quite sure about the costs and benefits of this additional one-third of sunlight as compared to the production/maintenance expenses of a solar panel etalon.
