Broken photovoltaic panel

[Kabi]

Hi, I bought two panels, see the link below. I measured the panels before buying and they had label values. When I measured them not mounted on the roof, so did I. After mounting and connecting the panel in parallel, the panels give 0V even after disconnecting and measuring the panel separately, the voltage is still 0V. I'm already clueless. Thank you for every answer.

Multisol® 200 M5 220/230 - Scheuten

Multisol® 200 M5 220/230 - Scheuten

www.yumpu.com

 

[Chriskruger]

Are you using a DC volt meter?

 

[Kabi]

Yes I use a DC multimeter. There is no problem with the multimeter, I tried it first.

 

[JWLV]

I've had panels that looked like it went bad but it was due to a connection issue and crappy soldering/cable. The small box under the panel where the MC4 cables come out of is usually the weakest point. If you can pop open the box, you'll see the connection from the solar cells to the pair of MC4 cables. You can check that to make sure the connection is still good. Another possibility is the MC4 connectors went bad as you were installing the panel. With the box open, you can check for continuity between the box and the end of the MC4 cable.

I had one panel with a similar issue that I couldn't figure out. In the sunlight, voltage would measure 0. When I brought it inside, I got 16 volts under normal inside lighting (light bulbs). As soon as it gets sunlight, it goes to 0. I suspect there's some kind of short as the panel generated more wattage. I never did figure it out and I ended up throwing the panel away. It was a cheapo no-name 50W panel.

 

[Kabi]

I measured directly in the box, still 0V. I have exactly the same problem you are writing about. In low light, under a cloud, in the evening, the panels give 12 to 15V. In direct sunlight, the voltage is 0V. It also seems short-circuited to me. The only difference is that these are quite good quality though older panels. But before assembly, they worked normally.

 

[sunshine]

In low light, under a cloud, in the evening, the panels give 12 to 15V.

This seems a bit low for open circuit.
If you take a panel down, open the box at the back and take a reading across each diode You may have to dig out the gunk for a good contact.
Should get the same reading across each diode. 18v in bright sun/across any one diode, 36v across any 2, 54v across all 3.
Less in dull conditions but they must be even..... not 12-15v across 3....unless very dull! To me it seems a diode (or 2) is in bypass

 

[Kabi]

It's a bit problematic to measure there, because the diodes are on the printed circuit board and when I put it on the bus, the diodes are towards the panel, so I can't get to the contacts so I can measure them. But do you think there will be bad diodes? So I'll try to replace them. Just for info there are 4 diodes.

 

[BiduleOhm]

I measured directly in the box, still 0V. I have exactly the same problem you are writing about. In low light, under a cloud, in the evening, the panels give 12 to 15V. In direct sunlight, the voltage is 0V. It also seems short-circuited to me. The only difference is that these are quite good quality though older panels. But before assembly, they worked normally.

Is the meter reading "0" or "0L"? because it's not the same.

 

[Kabi]

I know the range is right. It shows 0V.

 

[sunshine]

. But do you think there will be bad diodes?

No. Very unlikely. Still a possibility but most likely cell/busbar damage.
The diodes are used to go around faulty sections of panels.
Because the voltage reading is 12-15v it does look like sections of the panel isn't working. If the voltage was above 40v then most likely the panel is ok because that is greater than 2/3 Voc.

Edit: Looking closer at the photo there are 8 rows of cells...possibly 4 diodes.
12 rows of 8 cells = 96 cells. Each cell puts out about 0.6v...96 x 0.6 = 57.6....close to the stated Voc of 58v
If you look from behind the panel you can see the pattern of how they connect all the rows and where the diodes come into play.....this may give you some understanding .

 

[Kabi]

12 to 15V is low light voltage, full voltage is 0V. As if in a short circuit.

 

[sunshine]

12 to 15V is low light voltage, full voltage is 0V. As if in a short circuit.

I would not have gone past the 12 to 15v in low light before rejecting the panel.
The nil reading in full sunlight is a bit hard to explain...unless those rows, the only good ones, break down under full sunlight?
You really need to explore a bit more. Find a good row of cells and then you can compare that to the possible faulty rows.

 

[sunshine]

Hi, I bought two panels, see the link below. I measured the panels before buying and they had label values.

Maybe start from the beginning.
Take one panel off the roof and see if those stated values are still there.

 

[Kabi]

Thank you for all the answers. I'll try to measure and write what I found out. It's just a little problematic to measure each board separately, they have a special patented system for connecting to connectors, but maybe it will work out somehow.

 

[Kabi]

So the diodes are not bad. I tried to take out the printed circuit board with the diodes and the friend who has the same panels swapped the printed circuit boards and the panels also worked with my diodes. So please, does anyone know what the problem may be? So the panels are about to be ejected?