Solar-powered desk fans?

With summer right around the corner, I've been looking at solar powered fans, especially after seeing an episode of Ask This Old House where they installed an attic fan.

Unfortunately, it looks it's extremely hard to find non-attic fans, in particular smaller models that might fit in a window.

Since I've had such good luck with posting other items, I'm hoping that someone will come upon this and have some suggestions for where one can either purchase a pre-built, solar-powered, desk fan, or a site that walks through the creation process.

Even if there's no storage, it would still be nice on those warm days to have a fan that isn't pulling an electrical current ...