I installed 33 PV panels on my roof in July of 2012 and this summarizes the first three years. The panels are Canadian Solar CS6P-240M and were expertly installed by Revision Energy out of Portland, Maine.
This first image shows my production for 3 years. 2012 is shown in the blue background as the graph looked funky without the first 6 months of data. The trend is pretty clear but you can see how much things vary year-over-year.
To make it easier on the eyes, I averaged out my production across the three years, by month, to show a much simpler view. I also averaged my annual consumption (the faded red color) over the most recent 12 months to show my normal monthly usage (which is 917kWh* per month).
(*note: when I bought solar in 2012, I was consuming about 1200 kWh per month. That has since been lowered with mostly LED light bulbs, put almost everywhere in the house, and the elimination of a kWh hungry desktop computer…. see previous posts)
In the end the panels produce 75.3% of all my consumed electricity.
In addition, from April through August, during that three-year period, I produced more than 100% of my electricity (5 months) and the excess or “banked” kilowatt hours filled the gap in September, resulting in 6 months with effectively no bill.
In 2014, my “banked” kilowatt hours also covered the gap in October, yielding me 7 months of no bill. (Caveat: that’s not totally correct because the electric company has a minimum bill of $11 to $12 per month no matter what).
From a $ perspective, I’m producing about $1,200 of electricity per year. As electricity prices rise and panel prices fall, it will get better for new buyers.
Here is a great article on where energy production is headed.