The system was $22,200 US. I can get a Federal tax rebate of $2,000 when I file my taxes this Spring. I am also getting a check for $4,200 from a state agency (Wisconsin). The Federal tax credit was 30 percent of the system cost, but was capped last year at $2,000.
As of Jan 1, 2009 it is still 30 percent , but no cap. So if I bought the same system this year the tax credit would be 20,200 - 4,200 = 16,000 * .30 = $4,800.
However, I got in on a deal with the local Electric utility where they were offering 10 year contacts to buy renewable energy (my electricity) for 22.5 cents a kWh. Sweet. If the price I pay goes above that I can opt out and still get net metering - I would get paid the same price per kWh that I'm charged.
Most but not all states have net metering laws on the books.
DSIRE: DSIRE Home
So anyway, my net cost will be about $14,000. The cost per kwH used to be 5 cents or so, but is up around 10-11 cent now. The panels have a 40+ year lifespan, so I'll not be needing new ones for awhile. Expect it to "pay for itself" in about 14 years, but it's already paid for itself as far as I'm concerned.
PS another useful link:
http://www.homepower.com/home/