Chris Hogg wrote:
On Mon, 19 Aug 2019 19:59:04 +0100, Chris Green wrote:

I know only too well that a (for example) 250 watt solar panel doesn't
produce a continuous 250 watts for 24 hours a day every day of the
year. There's those things call nights, not to mention dull winter
days, and even dull summer days.

I've searched diligently but I can't find a site providing what seem
to be realistic 'ball park' figures for UK regions. I suspect there's
a special word for this percentage which I haven't found.

So, can someone either provide a figure for the average output of
(say) a 250 watt panel over the year in eastern England or point me at
a site that will tell me this. (I seem to remember the figure is
something like 20 to 25 percent, so I'll get an average of 60 watts or
so from a 250 watt panel).

I think Harry gets about 15%, and that's pretty good. He's about 10
miles SW of Worcester. The average for commercial solar farms in the
UK is about 9%, 20-25% in Summer, down to about 4% in Winter, IIRC.
South of England better than the north, obviously, but east versus
west probably makes little difference. Optimum orientation and lack of
shadowing more important. It's questionable whether solar panels in
Northern Europe actually produce more energy in their lifetimes as is
used in their manufacture. South of France, North Africa, California,
yes, fine there, but not in Northern Europe. Without subsidies, or
misleading claims by mfrs and installers, it's doubtful whether anyone
in the UK would install them.

Some links to individual records/comments/experience:
http://www.viridis.net/energy/solar-pv.html
http://tinyurl.com/q2993y9
http://www.jaharrison.me.uk/Misc/Solar/index.html

Thanks, *that's* the sort of stuff I wanted to know. So my 20-25%
figure is a summer figure. The winter figure means I can only run a
10 watt or so pump from a 260 watt panel and even that requires enough
battery storage to keep going for several days I would guess.

--
Chris Green
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