But here I'm strictly talking about the economics of it. So walk me through it -- You pay about what, 11 cents/kwh in IL? So $60 buys 545 khw. Here in California you would need 270 watts peak power to get you 540kwh in a typical year, but I have to presume it's more in IL, not even counting snow days. So you can get 270 watts -- or I suspect more like 350 to 400 watts where you are -- installed for $1,000? That's installed -- panels, construction, wiring, inverters, insurance, grid-tie equipment etc. You can't even get the panels for that price, uninstalled, but that's changing.

Now Illinois does have pretty good rebates (50%) thanks to the taxpayer, so maybe you could do it there, or rather the taxpayer could. And I'm not saying that it's necessarily wrong for the taxpayer to subsidize solar over carbon methods, just that we should understand what's going on.

Oh yeah, and $60 was the figure at 6 percent in a very safe investment (safe as houses, in fact :-) with no reduction of the principal. Solar panels are not so safe an investment, since their value will fluctuate with the cost of grid power and the cost of replacement panels.

The real comparison is more complex than this, mind you. But solar installs don't yet pay for themselves compared to grid power. They only barely pay for themselves when you factor in how much you or the taxpayer values you being green.

However, to make things more bleak, what if you buy cheaper grid power and put the savings into carbon credits at $4/tonne?

540kwh of carbon-burnt grid power adds 216kg of CO2. You can offset that for about 87 cents and now you're cleaner than solar.

In fact, at today's carbon credit prices, you are a gross polluter of the atmosphere, because for the same money you spent on your PV system, you could have bought grid power, and put the savings into carbon credits to offset not just your own power use but the use of many other homes. Now many poeple feel the prices should be higher, and they are higher in europe, but that just reduces the number of homes you could offset.