DIY

Depends on your particular County rules so that's worth looking into but like I said if you do not get a grid tied system a lot of the rules that people worry about generally don't apply.

An off grid inverter is basically like a computer backup UPS but on steroids. It accepts the grid as an input that it can pass through when there's no solar or you don't want it using the batteries but it is not capable of putting energy back into the grid under any circumstances which means the regulations on it go way way way way down.

As soon as you try to grid tie there is a mountain of litigation both at the federal and county/state level, it generally has to be done by a professional and there's a million inspections along that path even with professionals. But with off grid inverters depending on your location there may be very little rules at all. In my area I don't even need to report it to the power company that I'm doing it