The advantage that solar planes have is that they have the ability to hover over a location without having to orbit like a satellite or return to base for refueling like another plane. According to Qinetiq, solar airplanes are exciting because they have a variety of uses, including monitoring forrest fires, military communications, and tracking (locating pirates off the coast of Africa maybe?)
Even though this is unrelated to the concept of solar planes, I have to admit that what drew my attention to this article was the fact that the winning airplane was named Zephyr. I love that word, so for those who don't know a Zephyr (noun) is 1 poetic/literary a soft gentle breeze. 2 historical a very light article of clothing. Its origin is late old english zefferus, denoting a personification of the west wind, via Latin from Greek zephuros (god of) the west wind.
It also happens to be in the title of one of my favorite songs. So here's the Zephyr Song, by the Red Hot Chili Peppers.