I think it cost 10 or $20,000 about 10 years ago to put an all new roof on a barn my mother has now. Plywood, felts, Shingles, ect.. only thing not replaced was structeral members. And that was a lousy job too! I can look at the roof from the ground and see warps, buckles and waves rolling across it, but at least it does not leak and looks good if you don't look close.
Something like that would have paid for itself many times over now with solar panel roofing like I mentioned. Just a moisture barrier and interlocking panels to roof it.
Open drafty barn so heat inside is not a problem.
Her house was using electric hot water heat about 100-200' away too. So winter cooling of the panels (if needed) could have saved a ton in electric hot water heating. Durring the summer still heat the house hot water tank and if needed just waist the rest of the heat, or find some other use for it.
Figuring the cost of the normal style roof she got off the cost of solar and the large area to cover, her normally ridiculous electric bill would have paid the differnce about now I think for the whole setup includng some batteries. Most of the bill is hot water, electric hot water heat.
And the house roof is nearly as big as the barns, and its a new house (about 10yrs).
She doesn't listen to anything I say, so of course it's all electric and propane. No RE at all!
If I inherit the house someday I will either sell it and send the kid to collage or just burn it down and use the barn for storing cars!