Findsolar.com has a neat solar calculator that shows how well a solar-powered residential electrical system would work in your area.

According to the calculator, St. Louis has a “good” rating for residential solar energy — 4.859 kWh/sq-m/day, to be exact.

According to the Department of Energy, the average electric bill in Missouri is $79.48 (November 2007), and the average monthly consumption is 1,069 kWh (12,828 kWh/yr).

Using those figures, solar electric power in Missouri (through Ameren utility) would cost 8.8 cents/kWh (currently Missourians pay an average of 6.3 cents/kWh) with an average monthly electric bill of $94.

The calculator estimates the cost of installing a solar energy system on a home at $43,000, after a $2,000 federal tax credit.

Therefore, the estimated savings will look something like this:

(The above is based on an assumed utility inflation rate of 3.78 percent.)

That’s not great, but it’s better than many states — the SmartEnergyViews blog notes that in Tennessee, the payback for a residential PV system would take roughly 95 years. On the other end of the spectrum:

Folks living in Florida…can get a much better deal, because a) they get slightly more solar radiation, but more important b) they have a state rebate incentive that will pay for half the system.

Are those numbers good enough to spark a solar energy revolution in Missouri? Perhaps not quite yet. But with solar technology rapidly improving and energy costs skyrocketing, it might not be long before residential solar power starts looking pretty attractive.