Accidentally drilled the bottom of my panel.

yrtrnc · May 2018

Hi

I accidentally got the drill bit caught on the underside of my solar panel. The white plastic on the back was damaged and there was some metal pcs also. Very little damage to to the metal pcs.

Checked the panel voltage and all seemed fine. No heating up around the damaged area as far as I can tell.

So will the panel die? Is it going to cause a fire?

Thank you

DanS26 · May 2018

yrtrnc said:

Hi

I accidentally got the drill bit caught on the underside of my solar panel. The white plastic on the back was damaged and there was some metal pcs also. Very little damage to to the metal pcs.

Checked the panel voltage and all seemed fine. No heating up around the damaged area as far as I can tell.

So will the panel die? Is it going to cause a fire?

Thank you

Moisture now has a way into your panel. IMO seal the hole as soon as possible. Use a good quality sealant.

If you have nicked a cell, that is not good. Keep checking the output of that panel especially under full sun conditions.

Photowhit · May 2018

I've ripped the backing pplastic in the past. I used liqid electrical tape / plastic tool dip and it has done a nice job of sealing it up.

Estragon · May 2018

A pic of the damage may be helpful also.

yrtrnc · May 2018

> @DanS26 said:
> yrtrnc said:
>
>
> Hi
>
>
>
> I accidentally got the drill bit caught on the underside of my solar panel. The white plastic on the back was damaged and there was some metal pcs also. Very little damage to to the metal pcs.
>
>
>
> Checked the panel voltage and all seemed fine. No heating up around the damaged area as far as I can tell.
>
>
>
> So will the panel die? Is it going to cause a fire?
>
>
>
> Thank you
>
>
>
>
> Moisture now has a way into your panel. IMO seal the hole as soon as possible. Use a good quality sealant.
>
> If you have nicked a cell, that is not good. Keep checking the output of that panel especially under full sun conditions.

Hey

I sealed it over with electrical tape but will use silicone to do it properly.

If I nicked the cell would it be shorted? Can it cause a fire? How would I know if I nicked the cell. It was mostly white pcs that were damaged and there were a couple of silver pcs.

If it's just one dead cell I can live with that. Just afraid of fire and the whole panel dying eventually.

mike95490 · May 2018

the silver pieces, sounds like the tinned tabbing conductors. Do you see any missing chunks from the front side, where the drill grabbed bits of the tabbing ? If some tabbing wire is damaged, there will be trouble eventually, there seldom is any reduancy in the panels.

littleharbor2 · May 2018

yrtrnc said:

>
Hey

I sealed it over with electrical tape but will use silicone to do it properly.

Apparently silicone isn't impervious to moisture and can be corrosive. You should use something like a 3M 5200 sealant. Clean the area to be sealed very well to get a good bond with the sealant.

mcgivor · May 2018

littleharbor2 said:

yrtrnc said:

>
Hey

I sealed it over with electrical tape but will use silicone to do it properly.

Apparently silicone isn't impervious to moisture and can be corrosive. You should use something like a 3M 5200 sealant. Clean the area to be sealed very well to get a good bond with the sealant.

Agreed, polyurethane sealant is far superior to silicone.

Estragon · May 2018

Epoxy would be another alternative. It's less viscous than 5200 so can be better at getting into small crevaces etc. for a waterproof seal.

yrtrnc · May 2018

> @mike95490 said:
> the silver pieces, sounds like the tinned tabbing conductors. Do you see any missing chunks from the front side, where the drill grabbed bits of the tabbing ? If some tabbing wire is damaged, there will be trouble eventually, there seldom is any reduancy in the panels.

I will check the front side of the panels.

Trouble meaning fire?

BB. · May 2018

Just to be clear, if the cell is damaged--There is no way for the panel to still work to 95% of specifications. All current flows through all cells (or 1/3 or 1/2 of cells, if there are bypass diodes--And if the current does bypass an open/broken cell, then the Vmp of the panel will be cut to 1/2 or 1/3 of rated value).

Also, "standard" silicon seal has a "vinegar based" curing process (acetic acid) and would not be good for sealing solar panels.

-Bill

Photowhit · May 2018

BB. said:

... Vmp of the panel will be cut to 1/2 or 1/3 ...

Wouldn't that be the current/IMP?

BB. · May 2018

Generally, (modern) solar panels are all a single series string of cells (36, 60, 72 for Vmp=18/30/36 volts). All current (Imp) goes through all cells (in series).

There are (or where) some configurable panels such as Evergreen panels that had jumpers for 18 or 36 volt panel (and Imp would be 2x or 1x).

The "bypass" diodes are there to allow current to go around shaded (or open) cells (you don't want 300 VDC across an open or shaded cell--Typically ~12 VDC is considered the safe "reverse diode junction" voltage for solar cells).

-Bill

Estragon · May 2018

So the bypass diode is sort of like an electrical valve taking a 12v tap off a 24v bank if one of a pair of series connected 12v batteries went bad?

You still get 'X' amps depending on light, but at lower voltage.

BB. · May 2018

Yep.

Bill

yrtrnc · May 2018

So if the voltage coming from the panel is OK then I probably didn't damage the cells then?

littleharbor2 · May 2018

If you have damaged a cell you might find lower amperage coming from the panel. Current produced by the cells is directly related to the size of the cell. You could split that cell in half and still see normal (approx. 0.5 volts) from it, but half the current of a full cell. A better way to test the panel would be to put a load on it and find out if the voltage and amperage are within spec. If you have, or can get, a DC clamp meter you could connect the panel to a 12 volt battery, (not fully charged) and check the current flowing into the battery. I don't recall the nominal voltage of your panel, if it was mentioned, but that shouldn't matter if testing the current this way. Make sure you have the polarity correct when connecting to the battery

mcgivor · May 2018

One thing not mentioned, is there any visible damage oi the reverse side, looking at the cell itself where the drill bit pierced the backing, or by careful measurement establish where exactly the penetration is, you may have been lucky.......or not, if the interconnect is damaged to the point of being a weak link. The cell strings could be checked individually in the junction box by removing diodes, but short of that, monitoring the voltage and current by isolating the panels and applying a suitable load to establish if any initial damage has occurred. The word initial is used because over time things may change, hopefully it is minor damage and replacement isn't required, good luck!

Dave Angelini · May 2018

A really well made solar panel, like Sunpower, Panasonic or LG monos have 25 year product warranties.
One of the many ways that they can do this is each cell has 3 or more redundant connections.

Even with "some" cell damage they are able to meet their warranty power specifications.

They do other things also! They would not be happy with drill holes so use a piece of wood next time to protect it.

As mcgivor said load test or use an ammeter and short circuit test the panel against a good one for an hour at noon.
Leave them out in the sun all morning and get the panels nice and hot.

solorone · May 2018

As others have said they sealed the damage, and I did the same thing, but I used J B Weld and HVAC aluminum tape. piled it on the tape and pressed and sealed, been there 5 years .

Estragon · May 2018

I personally wouldn't use a potentially conductive foil tape for the repair, but if it worked, that's great.

kc8adu · May 2018

i have repaired backing damaged panels.
i used electronic grade silicone.
it is alcohol based rather than acetic acid.
you can get it at walmart as permatex ultra black.
its what i use to reseal automotive modules i have repaired.

cow_rancher · May 2018

Permatex ultra black also works great for repairing cracked lawnmower gas tanks, which happens often in AZ

yrtrnc · May 2018

Here's what the cell looks like from the front. Opinions?

BB. · May 2018

If it is easy to get at and monitor--I guess just watch and see what happens. If the area is "open circuit", probably nothing bad will happen.

If the area is "short circuited", much of the current will flow through the point and cause over heating.

The underlying problem is that we really do not know what to expect in future. One of the best ways to test a part/system's reliability is to thermal cycle/thermal shock it--Accelerated Life Testing (sun rise, sun set, hot panel with cold water sprayed on it). More than likely, the cracks will spread and and possibly change the open/short condition of the location.

-Bill

Estragon · May 2018

Looks pretty nasty to me. From what I can tell, there appears to be cracking penetrating the front of the panel, which can allow water to penetrate. Aside from potential electrical problems, water in the cracks could freeze and cause further cracking and/or delamination.

Assuming the panel is working at close to normal now, I'd take it out of the array, tape a square of plastic over the front of the damage, flip it over so it's horizontal back side up. Fill the back damage with a bit of 2 part epoxy (readily available in small tubes at hardware stores) or "creeping crack cure" (available at some marine outlets). Cover the back repair with another square of plastic. When the epoxy is set but not fully cured (time varies with ambient temp and hardener type), flip the panel over, remove the plastic square from the front and repeat on the front damage area. Wait a day or so for full cure and retest before reinstalling.

Accidentally drilled the bottom of my panel.

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