We have goats, it's a faff everytime there was a (heavy) shower I had to run out, open gate, move electric fence, bring them across behind house, round far side of barn, 5 mins later it would be warm and sunny again.
We got 4 chunky (6ft?)fence posts, 2 x 2mtre sheets of metal profile sheeting (left over from barn) for the roof, OH made a frame so the top would be safe if heavy now piled on it.
Dug holes+knocked the four corner posts in + compacted stone+soil in for stability, fastened the frame on, then the sheets to the frame, so it looks like a huge table, slightly sloping for run-off.
The goats love it, too sunny, showers, no problem there they are laid under the shelter. (it is also near a hedge for shelter from the wind.
(OH said they'd never get the idea to go under, I felt really smug when they'd 'got it' within a week

)