Ground mount may require a different permit even if you don't interconnect. My ground mount system needed a permit to be a legal structure- it is technically a shed; a 'non-dwelling outbuilding feature' or some such. It was a very easy permit to get in my little township, but that'll be different everywhere. This was entirely separate from the customer-generator contract we struck with the utility for electrical interconnection.
My 32 X 100W panels are not mounted at all, simply attached to one another by the brackets they came with. I have 8 arrays of 4 panels each connected in series, each panel propped up on one end by a concrete block with the other end resting on the ground. That's not what I had originally planned. I had 8 of them that I was going to use to power my refrigerator. I thought I could just lay them on the roof of the house, attaching one end to the shingles with silicone sealant. I thought getting a permit wouldn't be that big a deal since I never intended to connect them to the grid. I was wrong, of course. The electrical requirements were not that serious for a low voltage, off-grid system, but the engineering work to prove that the roof could support the weight, as insignificant as it seemed, and the wind resistance certification made the entire project a no-go, but when I tried to withdraw my application for a permit, my request was rejected on the grounds that the panels were "installed", even though by then I had placed them on the ground. All the while, I had another 4 panels on the roof of our shed, which were supplying power for a DVR and security cameras. I now believe that was causing the City to insist that I continue with the permit. When they sent a letter threatening me a with a court appearance and fines, I removed them from the roof of the shed and wrote back asking them what type of permit I would need to leave them all on the ground, making the point that any type of ground mount would be less secure in a hurricane than laying all of them flat on the ground. It's been more than a month and I haven't had any response. I'm guessing they haven't developed requirements for my application. In the meantime, I've bought more panels and an electric car, which so far has been entirely powered by solar for the limited amount of driving that I do. I'm hoping that in the end I won't have to pack everything up, put it away, and see my electric bill skyrocket.
