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Thread: : PV panel surgery
face picon face BY : RussellMc email (remove spam text)

Summary: Comments and ideas  welcome. re performing surgery on
Silicon/glass laminated PV panels

I have access to a useful number of new Silicon / glass (standard
construction) 300W PV panels which have "low output".
"The price was right" even with their issues.
And even better if restorable.
I'm surprised that these have reached here in this condition as other than
utterly nominal testing would have shown the fault.
(Factories I have been involved with have used Xenon flash illumination to
plot full load lines for every panel).

There are 72 cells per panel in 6 strings of 12 panels.
These should produce about 46V oc but do not produce much above 30V.

It appears that the problem is caused by shorting of top and bottom of
wafers where they are solder tabbed between wafers in some only cases. It
is possible to identify locations where this appears to have happened but
not possiblt (AFAICS) to visually identify such locations with certainty.

I have yet to try several possible methods but think it may be possible to
identify cells that are shorted using
- hall cell current sensors or
- capacitive signal coupling through glass or
- selective illumination of cells.
- Other ...

Repair is the issue.
It seems likely that I need tp access solder joints where top and bottom
cell tabs are joined top to bottom by solder bridging.

I can try:

- Induction heating - seems unlikely to work.

- Drill small hole though front glass with eg Dremel and diamond ball
cutter - possibly add a wall around hole area (blue tack? :-) ) and water
Seems likely to allow very precise bad-joint targeting IF glass shattering
can be avoided.

- Drill through rear sheet (TEDLAR/EVA or similar). Slightly harder to be
absolutely accurate. Need to drill between cells so minimal width. Harder
to resolder.

- ...?

Comments and ideas re "drilling" welcome.

Holes can be filled with a suitable sealer made for PV panel frontsheet

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