Our SolarEdge had enough capacity to add an extra 10kwp (we had 6, and now have 10 - so there's still capacity left to grow). We still had to go through all the rigamaroll with permitting, SDG&E, etc. So it was like getting a whole different system in that respect. However, the system itself expanded without issue. We have a battery coming as soon as LG starts cranking them out again. So that will be another "goaround" with permitting and the PoCo. We don't get any state or local rebates in this part of CA anymore (except for the battery via SGIP), but the 30% federal tax credit is still in play (for both the add-ons and the battery - if it ever gets here). YMMV in NY, but as long as your inverter has extra capacity, it should not be a big deal to expand your system. Also, as mentioned above, you may hit a speed bump with net metering if NY is in that arena. Because of all the permitting needed here in CA, the PoCo knows when you are up to something with your system, and they're keen to reset your billing option - particularly as they relate to time of use schedules and NM 2.0. However, within 5 years, even the grandfathers will be on TOUs along with everyone else, and they'll probably be charging us in 15 minute increments - an "instantaneous demand rate" system is where they'd really like to be.