"The roughly $100,000 project should pay for itself in about 10 years, followed by decades of big savings as the solar panels keep making power, Trimble said."     I wondered how long is the life of a solar panel?  I looked it up and found this - What Is the Lifespan of a Solar Panel? Photovoltaic (PV) modules typically come with 20 year warranties that guarantee that the panels will produce at least 80% of the rated power after 20 years of use. The general rule of thumb is that panels will degrade by about 1% each year.Apr 20, 2014   Just food for thought - not making any point.