yes, this article of bernhard's was a major wake-up call for me.

Amen for two reasons:

"My brother plastered our parents old house, a bigger business building, with 2,000 square feet of collectors and the electricity he sells will recoup the investment within 8 years. After those the panels will generate safe net income of several thousand Euros per year.

By my calculations, 2,000 square feet = 185.8 m^2, that's 340 of these
http://www.unlimited-power.co.uk/sunpower_high_efficiency_solar_pv_panels.html
@394.08 each = gbp 133,987.20 + VAT and fitting and control gear ... with a payback time (at current rates) of 40-50 years (depending on how much the control gear costs).  < Imagine my puzzled expression here! >  I wonder (again) whether I'm on the same planet ...

Secondly, someone commented that they were installing enough PV to generate 3x their usage.  I ran the calculations for me: two people living (I thought) fairly frugally (compact fluorescent throughout, no TV or tumble-driver, electric oven, fridge, freezer, kettle, but heating and hot water from gas), using on average 100KWh/week -- about 5MWh/year.  To generate this I'd need 30 panels -- nearly gbp 12000 + control gear + taxes -- and more roof-space than I have!

So perhaps 5MWh/year is not frugal!  Did I mention the computers?

http://www.dti.gov.uk/files/file20328.pdf says that in 2003, average domestic electricity consumption was 4600 kWh per household (3918 KWh in the N.East where I am).

So this is a wake up call to me: There I was smugly thinking: I was "doing my bit", "ahead of the pack".  Obviously I'm not.  I'm going to have to think about whether a household of 2 needs an always-on house-server (music, internet, email, ...) but that's "only" using 130W as I write, I'm going to have to look at a lot more than that :-(