On 19/08/2019 21:47, Chris Green wrote:
Chris Hogg wrote:


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.

When I used to try to charge a leisure battery off a small panel to run
an intermittent stable light in the winter, the actual performance was
in the low single figures percentage, not actually worth doing. (Now I
just use a couple of camping lights with lithium batteries).