There have been a few flimsy solar powered aircraft, and it wouldn't hurt to put them on here either if you are flying 45 miles away somehow to no power and can wait a few days for it to recharge, but I don't expect much contribution for the duration of a "normal" flight, unless you slow down to the speed of a bicycle or something and have one not-too-heavy passenger and no payload.
All timeframes above are complete swags.
Here is another one, I forget how fast, maybe 25mph or something on a slight decline...
http://www.wired.com/autopia/2011/05...tional-flight/ Initial scan of the comments seems to be in agreement with what I'm trying to say. 100+ million dollars for 25mph?