This document discusses the costs and savings of installing photovoltaic (PV) solar arrays on buildings in New York City. For a 5 kW residential system costing $35,000, various incentives including rebates and tax credits can reduce the cost to $8,750. The system would produce 5,750 kWh annually, saving $1,200 per year at $0.21 per kWh, resulting in a 7.3 year payback period. For a larger 25 kW system on a non-profit building costing $150,000, incentives reduce the cost to $112,500, and it would save $6,000 annually over its 30-40 year lifespan.