Does it come from the sun? Is it related to the sunshine? Does it depend on sunny rays of light to function? Then it's probably safe to call it solar.
The ancient Egyptians worshiped the sun god Ra, shaping their lives around the sun's golden rays and even following a solar calendar. Today sun worship is experiencing a renaissance, as more and more people become interested in harnessing the big star's power for "solar energy." Whatever way you decide to partake in solar enjoyment, just remember to wear sunblock.