30 percent on everything that you had to do to get the solar once completed. If new construction you cant claim the construction at all . If you modified existing for the solar it can be claimed for the modification . Many different hoops .
Mine was quite simple for hooking to the grid . Very few here use solar for now . Thankfully i where i live its not ruled by people who have nothing better to do than tell others what they can do on there place no home owners association just good old fashion help the other neighbor when they need help power company just comes out changes a few things checks the stickers(several required ) then off to the races it is.