Homes consume 30-40% of the energy generated in the U.S. If the average three bed room California home (gas heat, no AC) installed a 5 kW PV system, over the 30-40 year system-life the family could save the equivalent of :

170 tons of coal   or   26,400 gallons of oil

and prevent environmental pollution to the tune of:

180371 lbs of CO2 123 lbs of SO2 164 lbs of NOx

Furthermore, energy-efficiency measures may reduce electrical use and PV system costs by as much as 50%, and lower gas costs by up to 45%.

Using photovoltaic and saving energy also preserves life and prevents nuclear waste, oil spills, dam projects, deforestation, soil erosion, ozone depletion, health problems, military spending, and much more.