NYTimes author Jim Dwyer wrote an article (also there is an entertaining video) about his experience getting solar panels installed on his Washington Heights co-op building. After incentives, low-financing, and a very competitive bid from AltPower, he says they will roughly break even throughout the life of the loan and be in the black for the remainder of the life of the panels, which are guaranteed to last for at minimum 25 years.
But the real juice to his story comes from his retelling of uncooperative incentive policies, complicated regulations, and unnecessary ConEd needs. Solar could be a real boon for NYC because of our huge demand and very restricted supply (all of our blackouts are because of high demand and not enough electrons flowing through the wires). The problem is that obviously (except maybe to Albany) incentives that are appropriate for single-family suburban homes are not for the big city.
This is why we started our I Heart PV program, to get grassroots support for proper solar incentives for NYC. Head over there to read all the great arguements and what you can do to help.