As the garage has no mains power (oh no! here we go again!) I have bought a solar panel and controller to have a play with. It won't power tools or any heavy current stuff, it'll be there mainly for LED lighting.
As the garage is in a shared block, I wanted to make the mounting semi-removable so came up with this arrangement.
Heath-Robinson would be proud!

And here it is mounted on the garage soffits (or whatever you call it)
It is substantial enough to hold it all up but can be taken down (when they clean the moss off the roof?)
It isn't perfectly aligned but gets enough light for a reasonable charge rate.