100W solar panel not working

[Gsailor]

I had to remove a solar panel.

I thought I was careful.

But I measured the voltage the other day and it was about 10Volts (open circuit) whereas another panel I removed was over 21V open circuit.

Anyone know what I should be looking at first of all?

It is a glass covered panel with aluminium trim (that I had to remove and refit in order to remove the panel)

Could I have damaged a joint under the glass? Or should I be looking at the back where diodes reside?

Is it possible I damaged some solar wafer? That would be beyond my repair skills as far as I know. It is a polycrystalline panel in case that makes a difference.

Thanks

 

[B27]

You could check the connections at the back of the panel.
Measure the short circuit current as well as the OC volts, it's better indicator of whether a panel is any good.

 

[Bergamot]

I had exactly the same issue with a similar panel. Dampness had affected the relatively flimsy embedded connections in the back of the panel. Trying to dig back to find a sound connection rendered it totally useless. However, it had lasted 10 years and cost very little so it did quite well. I have replaced with a similar wattage (25w) for under £20 and just had to cut down my back plate for the smaller size. The new one seems much more efficient - progress?

 

[noelex]

It is probably unfixable, but it’s worth checking the bypass diodes to see if one has failed. The diodes are cheap to replace if one tests faulty.

On rigid panels the bypass diodes are normally in a plastic box glued to underside of the panel.

 

[Gsailor]

I think I may have twisted the panel or distorted it a bit when removing it.

If the diodes work out as OK am I right in thinking the whole panel is made of small solar cells soldered together?

Could I have broken a link?

If I remove the glass, can I check each small panel? What voltage should each small panel give (although it should be easy to find a duff one ... he says...)

I could then possibly bridge the duff small panel?

I have time in my hands, so don’t mind fettling.

The whole solar panel only gave 10V OC when the other working panel gave 21V OC.

I am hoping I broke a soldered joint.

Any views?
Thanks

 

[noelex]

Each cell should be about 0.6v.

If it is not the bypass diodes then unfortunately your chances of accomplishing an effective repair are slim, but you have nothing to lose.

Good luck.

 

[William_H]

Each cell should be about 0.6v.

If it is not the bypass diodes then unfortunately your chances of accomplishing an effective repair are slim, but you have nothing to lose.

Good luck.

More like .4 v per cell I thought. Not clear if OP removed the panel because of doubts about it's working oK. If it was working OK then he removed it yes he could have damaged a connection. I don't think you can remove the glass. Bonded on I suspect. If he can then he may find failure point but probably a throw away . ol'will