Earth Day Factoid:

If you have a photovoltaic system, you own a part of the 101 GigaWatts of installed solar power world-wide (as of the end of 2012). Collectively we are producing as much energy as the average delivered output of 62 U.S. coal-fired power plants. This figure is based on 1,980 billion kWh of electricity delivered by 1,436 coal power plants (in 2009), and assumed output of 90 billion kWh delivered by PV.  All this PV prevented the emission of 127 million tons of CO2 (from coal).