KM... 836 Posted January 23, 2019 Report Share Posted January 23, 2019 I have a 100W panel, do you want me to check something for you? Quote Link to post Share on other sites
Marshy 14 Posted January 23, 2019 Author Report Share Posted January 23, 2019 Cheers KM - i have two identical panels, and one is working mint so got a pretty good test bed. I hate throwing stuff away that i cant explain how they are broken! So curiousity will probably have me buy a new one for the boat, then play with this one at home to learn some more. Quote Link to post Share on other sites
KM... 836 Posted January 23, 2019 Report Share Posted January 23, 2019 No worries, they are there if you need them. Let us know how you go. I've never really had any pushing need to trouble shoot things like that but now I'll need to lift my game so keen to follow real life things like this. Quote Link to post Share on other sites
Crazyhorse 47 Posted January 23, 2019 Report Share Posted January 23, 2019 The way I read it was the panel under test was able to produce a potential under load of over 5 amps at 21v. That tells me the panel is producing over 100w! Did I read wrong? Quote Link to post Share on other sites
straycat 1 Posted January 23, 2019 Report Share Posted January 23, 2019 How old were the panels? I know Monocrystal ones tend to have working warrantee of upto 25 years. I did not think there was any electronics inside the panel, diodes will be in your controller. Quote Link to post Share on other sites
ex TL systems 57 Posted January 23, 2019 Report Share Posted January 23, 2019 I had a panel that had been underwater and the copper ribbon behind the connector had turned to green dust. I dug it out with a knife to get to intact ribbon and soldered 2 new wires on then sealed with silicone. Working fine. Seems they are pretty hard to kill. jim s 1 Quote Link to post Share on other sites
Dtwo 106 Posted January 23, 2019 Report Share Posted January 23, 2019 Trying putting them in the sun? Never forget the obvious answer... Quote Link to post Share on other sites
Marshy 14 Posted January 23, 2019 Author Report Share Posted January 23, 2019 Haha they were in the sun - hence one of them works one doesnt. @CrazyHorse - not really in that when you measure the Open Circuit voltage the current isnt at 5amps. Likewise when you measure the short circuit current the voltage drops a little. you cant measure the two together and get that. @StrayCat - Panels are probably 5 years old but they were bought by previous owner of boat so not sure where from etc. there is diodes in the connector box on the back of the panel itself. Quote Link to post Share on other sites
Island Time 780 Posted January 23, 2019 Report Share Posted January 23, 2019 often the cells have a good warranty, but the panel itself does not. Worth reading the fine print on any new panel. The diodes can of course fail on a panel like that. If they can be accessed they can be tested and replaced if required, but on many panels this is impossible - destroys the panel. Quote Link to post Share on other sites
Beccara 25 Posted January 23, 2019 Report Share Posted January 23, 2019 Sounds like a diode or a join in a string of the cells has gone, 9v at Short isn't bad for a 100w panel but it is a touch low. For example here is a different 100w panels volts/amps curve: Can you get us a picture of the black box on the panel with it's lid off if it comes off? Under the glass on the panel can you see any black/soot like marks between cells? Quote Link to post Share on other sites
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