7kw? Amazing! How large is the array? (sq ft) How much did that set him back?
Main issue I have seen with the law in FL for them is that they are net metered but the power bill can't go negative. So if they produce more than they use the power company doesn't have to pay them for it, also they always get a service charge no matter what. So their power bill ends up being about $20 a month no matter what which is just the service charge.
Now that 280 watt panels are becoming common, up to 7kw is a "standard" install.
I don't know about three phase.