Ok, nothing is free. There has to be a catch. Yes, it isn't technically free but you aren't really paying for it either. Ok, in a way you ARE paying for it by paying for the electricity produced by the solar PV system. So, you don't pay for it to be installed (hence FREE SOLAR) but you pay very cheap electricity rates on the energy that produced by the solar system. In addition, the company who IS paying for the system gets the other benefits, i.e. tax incentives and SRECs (where applicable).
So, let's review, Free Solar is a great deal with no money out of pocket that lowers your electric bill.