Our system is located in Minnesota, and while we can generate large amounts of energy all year long, the decreased hours of sunlight and snow cover impacts our production in winter months. On the flip side, the summer months are our super star performers. Our 7kW system generates well over 100% of our usage in the May-November months. The utility company “buys back” the excess resulting in a profit of $20-$60/month. Seriously, not only do we not pay for electricity during these months, but the utility company sends us a check each month!
Note that the $20-$60 is in excess of the savings that we are NOT paying utility fees for the month. We averaged $700/year or $60/month in electricity costs before the panels were installed. Therefore, the savings plus excess equal $80-$120/month of system profit.
In the winter months, our bills are defrayed by the system production but not covered entirely as shown in the chart above. The total electricity billing for the year has averaged a surplus of $100. Combined with the savings of $700/year and our system payback is now less than 7.5 years! ($5,775 cost/$800 per year) After that, it’s “free electricity” for the life of the system!
*Note: Our billing with the utility company experienced some kinks the first 6 months or so, so accurate tracking wasn’t available until April 2011.