Those 4x8 sheets of whatever the hellitis weigh a lot. I've picked them up and moved them. I wouldn't consider it myself but you can do whatever you wish. The question is how long will it take to recover the cost of installing them and how long before you need a new roof and have to pay to take them off and reinstall? Personally if I were to get them I would install them on the yard beside the house and let the roof do it's thing unhampered. Citizens National Bank outside of Corsicana Texas has a couple of banks of them and they take up more room than the building. How much they help with the electric bill , I have no idea. They sure are ugly though.
Good advise
When I move my System up to Arizona permanently I will be building a Carport type structure so that I can park vehicles or do work under the roof in the shade and out of the direct weather.
I already have the rack built. 1/2 at my place in Commyfornia and when I get to Arizona I will have 1/2 of it there to support the panels and get them off the ground
My System will pay for itself faster than people that have the Grid close by.
My place is remote and it will cost me just going back and forth getting Fuels for the Generator.
Like I said earlier.
Everyone's needs are different and you need to figure out what your needs are before you can make a good decision on how to fill your needs.
My Neighbor here in Commyforna just last year had a Solar System installed on the roof of his home.
He had hind sight and seen that he screwed up by not re roofing his home before the install.
The Company that Installed his System did not mention the re roof at all.
Probably so they can come back and be paid for removing the panels and re installing when he does re roof.
I asked my neighbor how many Watts he had installed and what kind of System (Inverters and Controller) he has no battery's
He gives his power to the power company (Edison) during the day and then uses the power company's power during the night.
All my neighbor could tell me about his System is that he only has to pay around $50 a month now in an Electricity Bill every month.
He has no idea of what he even has on his roof and really does not care to know.
