How good are modern PV panels in cloudy/shady conditions?

Do you make your own power ? be it Solar or Wind. Then this is a place for all home energy chat.
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Joined: Thu Dec 12, 2013 3:30 pm

Re: How good are modern PV panels in cloudy/shady conditions

Postby jamesingram » Tue Apr 15, 2014 4:17 pm

Interesting re. NW system . I was considering a small one on my NW roof in addition to my current SE one.
what bearing does the NW face seems a good relative output.
cheers James

Posts: 84
Joined: Sun Oct 04, 2015 3:45 pm

Re: How good are modern PV panels in cloudy/shady conditions?

Postby willfromsussex » Mon Nov 23, 2015 3:51 am

I have a home brew off-grid system comprising 9 panels (3 x 3 strings) running to a Outback FM80 charge controller which runs into a load of T125 6 volt lead acid batteries. The panels total 2250W peak . They are currently lying flat on a flat roof and in summer I was getting over 2000W peak and maybe 12 or 13 Kwh . Even with my rather wasteful UPS that i am using to make mains (APC 3000 which wastes 90 watts just powering itself) the system kept up and I could even run a washing machine during the day.

Now in winter I'm lucky to get 200 watts peak, I sometimes get only 1 unit of electric a day. I really need to angle the panels but when its overcast, like it seems to be most days, I doubt that makes a huge difference. Bound to on sunny days although the sun is so much weaker when it is at that low angle in the sky.

So this time of the year it takes several days to charge the batteries, with no load being drawn off, so I can only fire up the UPS and start using the power for around 1 day in 4. Rest of the time I'm on mains, although for that time I am buying power from Ecotricity, which are 100% from renewables apparently. (they are also the easiest power company to talk to, ask about stuff etc, can't fault their customer service)

The whole system only cost about £2000, and it doubles as back up power for power cuts, which living on a fairly remote farm, we do get maybe once or twice a year.

I wanted to be able to charge my EV with the solar but I can't do it on the current setup. Something for the future, maybe a larger UPS (5000VA) would do it , and some more panels.

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