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Over efficient panels?

Posted: Tue Aug 01, 2017 12:42 pm
by Chris19
Hello

I have just finished a self-build with a two by two array of 245w panels feeding a FM80 at 12v but promptly turned off the array when the mate read 2093w. Not only is this over spec for the panels, but the sun was at least 30 degrees beyond them.

Is this likely to be a panel problem or a setup/configuration issue?

Thanks

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 5:24 pm
by Mike Curran
There's no way you could miswire these 4×245W panels to get 2093 watts. If you've configured your FM80 for something other than 12 volts, not sure what effect that would have, but seems doubtful that could cause this. If everything's wired right I'd suspect the FM80. More details on your overall system might help forum readers diagnose the problem.

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 9:07 pm
by petertearai
4 panels in series could have gone over 150 volts?

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 10:02 pm
by Chris19
Thanks for the replies, but in reading them I see I have made a significant typo - should read 1093w - 12% over spec, sorry :oops:

The panels are in two pairs, so open voltage about 102, battery temp was 19C.

Chris

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 10:09 pm
by petertearai
brand new panels . cold . I would think not out of the question . was this sustained or over a short period ?. cloud edge effect .my system shows a maximum watts in excess if rated panels .. but don't know when or for how long .

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 10:20 pm
by blackswan555
Sub 25c panels and possibly "edge of cloud effect" But in North Yorkshire !!!!!! Wow :grin:

Tim

https://solarhomenews.wordpress.com/200 ... ink-it-is/

Re: Over efficient panels?

Posted: Tue Aug 01, 2017 10:28 pm
by Chris19
It was a break in the cloud and I disconnected the panels very quickly but the system has yet to be subjected to the full path of the sun and a clear sky. Thanks.

Re: Over efficient panels?

Posted: Wed Aug 02, 2017 8:19 am
by Mike Curran
Relax, you're fine, I've seen my first 1,440 watt (rated) array produce over 1,800 watts! Loved seeing it, too.

Re: Over efficient panels?

Posted: Wed Aug 02, 2017 7:43 pm
by larrywa
Chris19 wrote:It was a break in the cloud and I disconnected the panels very quickly but the system has yet to be subjected to the full path of the sun and a clear sky. Thanks.
Just wait until you get one of those cold crisp fall or spring mornings. The colder the better.
When we get those -25C winter days in Canada my panels put out 140% when they aren't covered in snow you guys send over here! :grin:

Re: Over efficient panels?

Posted: Wed Aug 02, 2017 9:15 pm
by blackswan555
It was a break in the cloud and I disconnected the panels very quickly but the system has yet to be subjected to the full path of the sun and a clear sky
No need to disconnect panels (& possibly a bad idea under load) The FM will limit itself to 80A anyway, Theoretically you could put any wattage of panels on it and still only get 80A "out the other side"

Tim

Re: Over efficient panels?

Posted: Wed Aug 02, 2017 10:03 pm
by Chris19
Thank you everyone for your comments on this thread and others I have found/read since, very helpful and reassuring. Winter will be interesting as the house is an old railway cottage in the bottom of a valley and will be in shadow for over a month, but then we are not there all the time. :grin: