Hundreds of possible solutions!!!

SPOILER: All lightnings go from upper right to lower left. (It remains little ambiguous, however "guessable"...)

I made one attempt. Too difficult to figure out which solution is right.

I spent a lot of time on this, but finally gave up. Too much guessing involved.

Gave up.

You guys are right, far too much guessing. Sometimes it is best to just quit! I always rate logical puzzles with 5 stars, this doesn't get a rate at all from me. Sorry author Fiona, Not my cup of tea :(

The middle bolt is 3 7's gradually getting large as you go down, one on top of the other. There are then 5 small bolts 2 on the left 3 on the right.

Multiple possible solutions. Thank you for the hints!

Even with all the hints, it's still pretty difficult. Bleh.

Thanks to Teesea and Joe Tramp for the hints! On the last part of the puzzle, make sure the top-left mini-lightning doesn't touch the cloud.

Teesa, can you please give some coordinates for the middle bolt? I don't thibk I quite understand your hint, and I've tried 100 different things now.

The 5 small bolts are little "stair" formations made out of 6 boxes each. They all go from the upper right to lower left, as stated by Joe. The bolts start at:
r2/c22 (part of the "3")
r3/c6
r11/c5 and c19
r14/c23

Along with Teesea's hint with the bigger bolt, it should now be possible to solve it.

Thanks for the help on the outside still can't get the middle though... Ging to try again with fresh eyes tomorrow...

Horrible.