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Hello guys i'm new to this forum. Pls, i recently bought suntech 10watt solar panel. I failed to test it upon buying. When i tested it later on, the open circuit voltage was ok, but the short circuit current was far below normal. Instead of 650mA, It was reading at noon, 201mA. Now i cant return the panel. But i was wondering if u guys can proffer solution for this problem. Is it possible that i can correct this problem. I tried opening the panel, but the glue is so hard. I dont know, but i was thinking that a kind of high series resistance has been developed inside. How i dont know. Possibly from poor electrode contacts. Guys what do you think?
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Was the panel in full sunlight facing directly at the sun when you tested it?
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You may have a blown / bad / missing bypass diode inside the rear junction box, leading to only a half-current capability.
Amazingly, even at this low power level, the Suntech divides the 36 cells into 18-cell halves, and uses bypass diodes to protect shaded cells from reverse-bias long-term damage. I don't own one, but check to see if the bypass diodes are ok.
If this is a return item, a previous owner may have attached the panel to a large battery in reverse polarity, and blown one of the diodes. The reason I know is that I did this to a Sharp 80w panel accidentally and had to replace the diodes myself.Comment
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Tnk you guys for your comments. Well, it was arnd noon that i tested it when the sun was very much overhead. You can see how shocked i was. As for the bypass diode, i doubt if the panel has any. Bcos, i didnt see any. I think all 36 cells are in series. But has anyone had similar problems or complaints b4?Comment
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ok. Guess i just have to use it like that for the time being. But something tells me that if i can figure the bad cell and remove it, i might reverse the problem. I am tempted to examine the cells however because of the panel's simplicity of connecion. But until i figure out a way to carefully do this, i think i am stuck with it for a while. Thanks.Comment
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That Suntech panel *should* have the diodes, but they may be hidden from view. Perhaps you should contact them to find out exactly where they are as their own documentation / sales material points out this feature. But if you have to bust open the panel to get to them, then just replace the panel under warantee.
As for testing, we know that if you cover a cell in a mono/polycrystalline panel, you should see a noticeable drop in current. Use a piece of carboard, or even just a small strip of blue painters tape, and place it over the glass of one individual cell and take your current measurement again.
If you see a drop in current, that is normal. Move the tape or cardboard to cover the next cell and repeat. When you cover a cell and there is no detectable drop in current, that cell is suspect.
I use this technique often with cheap "boutique" folding panels that I suspect are not putting out rated current. You can also use this technique with cheaper folding camping panels that use a lot of very small monocrystalline floor trimmings.
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ok. I'll see. I just tought that since all cells are in series, they neednt any diode. Its only10w. I'll try test them. And one more thing. Do u think that the glass covering of the panel concentrates sunlight? Would any normal glass pane do?That Suntech panel *should* have the diodes, but they may be hidden from view. Perhaps you should contact them to find out exactly where they are as their own documentation / sales material points out this feature. But if you have to bust open the panel to get to them, then just replace the panel under warantee.
As for testing, we know that if you cover a cell in a mono/polycrystalline panel, you should see a noticeable drop in current. Use a piece of carboard, or even just a small strip of blue painters tape, and place it over the glass of one individual cell and take your current measurement again.
If you see a drop in current, that is normal. Move the tape or cardboard to cover the next cell and repeat. When you cover a cell and there is no detectable drop in current, that cell is suspect.
I use this technique often with cheap "boutique" folding panels that I suspect are not putting out rated current. You can also use this technique with cheaper folding camping panels that use a lot of very small monocrystalline floor trimmings.Comment
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If you are thinking about breaking open the panel - don't. You'll break the moisture-barrier, and the panel will only survive a short time. This is something the DIY guys deal with in regards to encapsulation.
The glass on a good panel is usually tempered, and may also have anti-reflective properties. Concentrating light on a panel is ok if it diffused like coming from a snow-bank, but don't even think of using mirrors etc - you'll overheat the panel just like a good solar cooker does to meat.
I'd return the panel. Are you sure your metering is good? It isn't switched to something like AC current giving you errant readings is it?Comment
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ok. I see. Points noted. Thanks. I appreciate.If you are thinking about breaking open the panel - don't. You'll break the moisture-barrier, and the panel will only survive a short time. This is something the DIY guys deal with in regards to encapsulation.
The glass on a good panel is usually tempered, and may also have anti-reflective properties. Concentrating light on a panel is ok if it diffused like coming from a snow-bank, but don't even think of using mirrors etc - you'll overheat the panel just like a good solar cooker does to meat.
I'd return the panel. Are you sure your metering is good? It isn't switched to something like AC current giving you errant readings is it?Comment
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The only meaningful differences between the best glass and normal window glass are:
1. anti-reflection coatings which can potentially increase the light reaching the panels by maybe 4%
2. Low absorption glass that lets more of the light through, for at most another few percent
3. As mentioned, tempered or heat resistant glass for better mechanical properties when you drop it or the panel gets hit by hail.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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