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Old 31-03-2011, 14:05   #1
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Low Voltage on Solar Panels

Hello,

I was wondering if anyone might have some advice regarding the Seimens SM110 Solar panels I have on board.

I tested the voltage the other day at high noon down here in Panama and was only getting 13 - 14 volts. I have only tested at the wires coming into the charge controller.

I am wondering if the panels are shot or if there maybe other areas to test or clean?? The two panels are connected in series and there are for module boxes under the panels. Can this be a source of voltage loss?

Visually the panels don't look new that's for sure, they are 9 or 10 years old, there is some browning and some of the filaments look a bit distorted.

Are these panels ready for retirement or can I do some restoration to get the voltage back?

Thanks for any advice
Meck
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Old 31-03-2011, 14:10   #2
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Re: Low Voltage on Solar Panels

Check voltage at panels, might need larger guage wiring to charge controller if a long run or could be fault in wiring
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Old 31-03-2011, 14:17   #3
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Re: Low Voltage on Solar Panels

Quote:
Originally Posted by Meck View Post
Hello,


I tested the voltage the other day at high noon down here in Panama and was only getting 13 - 14 volts. I have only tested at the wires coming into the charge controller.

The two panels are connected in series and there are for module boxes under the panels. Can this be a source of voltage loss?
Did you disconnect the wires coming from the charge controller or measure the voltage with the wires attached?
Are you sure its series not parallel?
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Old 31-03-2011, 14:26   #4
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Re: Low Voltage on Solar Panels

Disconnect each panel.
Check voltage at each panel.

By wiring in series, if one panel is bad they both will look bad, so you have to disconnect each one and test to find the culpret.
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Old 31-03-2011, 14:41   #5
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Re: Low Voltage on Solar Panels

Do the panel wires come out of boxes under the panels?You have to open those boxes and look for corrosion.You need to measure voltage right there at the boxes.Any connectors/plugs between those boxes and the controller?You need to eyeball everything for corrosion.
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Old 31-03-2011, 14:42   #6
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Re: Low Voltage on Solar Panels

You have received good advice: disconnect the panels and measure the "open circuit" voltage.

Depending on the type of charge controller you have, and the state of your batteries, your 13-14 volt measurement could be indicating that the panels are perfectly good. This is the voltage range you will see when your batteries are in the second half of the charging cycle, and you are using a non-MPPT charger.

It would be useful if you had some way to measure the current coming out of the panels. I carry a clamp-on DC Ammeter that has proven quite helpful over the years.
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Old 31-03-2011, 14:51   #7
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Re: Low Voltage on Solar Panels

Tons of great information. Looks like I have another project...

Meck
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Old 31-03-2011, 18:03   #8
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Re: Low Voltage on Solar Panels

This may sound like an impertinent question but are the panels clean? A fellow we know went through all kinds of effort to cure a similar problem only to have the technician he finally hired to get things corrected stand there and wash off his panels--ipso facto--problem solved.

FWIW...
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