The cost and benefit of solar PV for your home: some blunt talk

An old friend of mine came up recently from Philadelphia for a visit. He lives in the suburbs outside the city, in a largish and probably old and somewhat leaky colonial home. His utility bills can run into the hundreds of dollars per month in the summer just for air conditioning -- it is definitely hotter and more humid down there than up here in Ithaca. When he saw my roof-mounted solar PV system he became very interested. "Up front it would cost me thousands of dollars, but then those huge air conditioning bills would go away," he reasoned. The reality is not as bountiful, unfortunately. If you front thousands for a 3 KW or 5 kW system, you will get hundreds of dollars PER YEAR in avoided electricity cost (at 10 or 20 cents per kWh, or whatever you are paying), not PER MONTH. This does not mean people should not invest in PV, but we need to be realistic here about what a system can return. In this particular example, improving the performance of the house so it requires less
A/C is definitely important as well.