On 20/05/2012 16:47, Dave Liquorice wrote:
On Sun, 20 May 2012 07:32:36 -0700 (PDT), Graham Easterling wrote:

I installed my panels initially as a 'green' measure, ...

Do you have figures to show that they will be energy positive over
their lifetime?

Yes. They do actually pay back their energy to create even at our high
latitude but only by about a factor of 4x energy of manufacture. See for
example David MacKays debunking of the myth that it never pays back
which is base on prehistoric inefficient thick film solar cells.

http://www.inference.phy.cam.ac.uk/w.../page_41.shtml

Installed somewhere sensible they would get more like 7-10x.

To put it in context the figure of merit for a wind turbine is about 80x.

... but they are exceeding expectations. I'm set to get my money back in
10years, even allowing for interest in the money (@ 3%gross) if it was
invested for the 10 years.

That is a pure financial expectation, nothing "green". A financial
benefit that would not exist without the huge FiT payments funded by
everyone elses electricity bills.

But if the government are daft enough to subsidise it that way...

Also changing all my 50W downlighters for 5W LEDs ... has made a huge
difference to my power bills.

You could have done that anyway.

And he will surely live to regret doing it.

High power LEDs retrofitted into existing luminaires not designed for
their proper thermal management will die young and horribly. Even some
of the better engineered mains powered LED units suffer from cooked
capacitor fatigue in the same way that computer motherboard PSUs do.

--
Regards,
Martin Brown