First, I did not say it was useless, I said "I dont think the average couch potato will ever get it"
Assuming you are an average couch potato, I would suggest that you did not break even. You simply did not understand the math. :P
Doing some rough math I come up with the following.
Checking my local electric I am paying $0.06 per kWh and if I feed electric back to the grid they pay $0.03 per kWh
Checking current prices and using the optimum output from the system a $28,000 system will produce 16,755 kWh a year. (The average American uses 11,280 kWh a year)
If you take the maximum output of the system multiplied by 10 years (The life expectancy of the system) then divided it by the cost to come up with a cost per kWh of $0.16
Then subtracted the kWh above the average American usage as a net gain of 5,475 kWh multiplied by $0.03 per kWh as the electric company pays you for that, then multiplied it by 10 years. (Total $1,642) to be deducted from the overall cost of the system.
This brings the electric cost to $0.15 per kWh on the system (Remember it cost me $0.06 per kWh from the grid)
The sales brochures will often extend the life of the system out to 15 years in order to reduce the TCO and show you making a small net gain.
All of the above is based on the system working at peek efficiency. The truth is you will average 8,000 to 9,000 kWh a year from the system not the 16,755 kWh as the real world never gives peek efficiency. Add to that the chance of the system lasting 10 years with out damage and costly repairs is slim, one hail storm (We have them here ever 5 years or so) will total a system are require replacement of the panels.
Now, the reason I did not say it was useless is because there are a lot of uses for Solar. I have researched it because the cost of solar is well worth it, if and only if you use it in a manner that get the best bang for the buck so to speak. A small hunting cabin in the woods is a great example. It is not used as a daily place to live, you can design the cabin to be extremely electric efficient, and because you are not there all the time the solar can take days/weeks/months to charge the batters while you are not there so that when you are, you have electric on demand. Add to that the cost being far less than paying to have electric lines run miles out to your cabin and you have major net gains using it in that instance.