This is the number of years it would take on the average for the system to
pay for your initial investment, assuming energy prices do not increase.
If energy prices do increase, the time will be shorter.
After this time period, the solar system will reduce your monthly electric
bill by the amount of energy it generates. If you are very frugal in
your energy usage, you could even have Austin Energy paying you every month.
This could go on for perhaps 50 years or more depending on how long your system lasts.