And this is more than a theoretical risk...

https://www.washingtonpost.com/news/powerpost/wp/2016/04/23/...

¿Por qué no los dos?

It looks like solar-powered zeppelins are a thing, although with the brief googling I did it looks like nothing really exists just yet.

Yea I guess I was more thinking of a kind of blimp, where it still has some solar to allow it to maneuver around, but not to actually stay up.

If the aircraft needs to stay in one place maybe that would be less efficient though, since it would be harder to fight winds.

You're basically describing the JLENS program, though the lighter-than-air craft was tethered, not free-flying.

https://en.wikipedia.org/wiki/JLENS

I thought that you could somewhat control a balloon by using different wind patterns in different elevations.

https://www.youtube.com/watch?v=NvJ2Ei8K2DI