I have considered solar panels too, but our roof is shaded by some big trees.
From what I have read, orientation (true S, not magnetic) and tilt angle can have a dramatic affect on panel output.
Columbus is in between 3.5 and 4 hours of peak sun per day averaged over the year.
However his 3.2kW unit should still be putting out more than it is if the panels are properly oriented.
http://www.californiasolarcenter.org/solareclips/2003.11/20031111-2.html
From this link we see a 1.5kW system can produce 1275kWh in its first 120 days of use, or an average of 10kWh per day.
I had been looking at something in the 5-7kWh range to make it worthwhile. However that is from 24-36 panels.
With rough dimensions of 40" x 68" that is a lot of roof.
My roof slants in multiple different directions meaning it would be quite a challenge to orient the panels for peak production.
There is a 3.2kW kit on Ebay for a little over $12K. It says it only needs 300sqft for installation.
It does not include the batteries, it is a grid tie system.
They estimate it could produce 4800 kWh/year, or a little more than one moths worth of use in my case.