Thanks for posting but expensive me thinks,i have a £26 unit doing the same job for solar and a £40 battery charge set up.
I would never put all my eggs in one basket and rather keep things simple and separate.
Great job.
Wheels are best shotblasted then primed with epoxy 2 pack & finished with polyurathane 2 pack.
Taking a cable through the roof is best done using a boat deck gland which can be bought on ebay cheap