PV Panel repairs

[Steven Fahey]

A friend of mine has been repairing PV panels. Not as a business or with any intention of re-selling them, but simply as a means of preventing them from going to the trash heap. A perfectly serviceable PV panel, scrapped because of a faulty diode or solder blob in the connection box? What a waste of hundreds of dollars of material, when only a 2$ repair is wanting. To him, this seems to be a common problem. I fully support what he's doing, and offered him some help.

When we identify a defective panel, we can usually narrow down the problem by measuring the output current in the sun, shading parts of the panel in turn until we find parts that don't respond to the shading. Taking the connection box apart, we find diodes that are shorted and connection tabs that are separated. Replacing diodes and re-soldering tabs is usually sufficient to restore the panel to full power.

We haven't gotten far with the repairs before discussing the implications. These panels were CE and CSA and UL labeled, but these certifications become void when the panels are modified. There are some provisions in these codes that allow repair, but only when the repairs comply with "manufacturer's procedures".

Well I've never seen a repair manual for a PV panel. I've probed the websites of many PV panel manufacturers, and found no such thing. While I do have a technical background that informs me on what's inside these boxes, what the specs are, and how I would go about doing a proper repair, I also admit that I do not have the specific knowledge that the panel's manufacturer has. I do not know the exact specification of silicone that the manufacturer used, or the rating of the schottky diode, or grade of solder, etc., although by observation and research I can make an educated guess that I think is reasonable.

My first question is, "do such "Manufacturer's Repair Procedures" actually exist, and can mere mortals like me see them?" If there actually is a way to repair them that complies with the manufacturer's procedures, then I definitely want to know!

I would also like to get a better handle on the scale of the problem of bad PV panels. If any PV installers happen to be reading this, question #2 would be "at what rate do you have to deal with dead panels, either upon installation/commissioning, or after being in service?"

[Rob Beckers]

Steven, I've fixed one of my own roof panels as well...
In my case arcing in the junction box left a mess (part of it melted away). Clearly a bad connection from the factory.

In general though, I don't see a lot of broken/failing panels. We once had lots from one specific manufacturer (materials defect I suspect), generally they tend to be pretty reliable though. I suspect that the failure rate is very much brand-specific, with the better brands doing much better than the so-so brands.

Personally I couldn't care less about voiding CE/UL/CSA certification if fixing a panel can put it back in service. Electrical code certainly has its place, but also its limits.

I have 420 panels on the roof of the Solacity building. So far they are working very well! Judging by the slight differences in Voltages and output there may be the odd failed/shorted diode in one or two of the strings, but it's not enough to go up there, tear strings apart, and measure each panel.

Great that you're fixing panels though! I suspect this could be a booming business!

-RoB-

[Steven Fahey]

Hi Rob,
Thanks for sharing your experience. If you rarely see this problem, aside from some bad product lines, that contributes to a growing suspicion of mine. On each the panels I repair, the label on the back has a name I've never seen before. On the other end of the spectrum from Kyocera and Sharp, so to speak.

I was also interested to read your opinion about the certification label. I have heard the opposite from a different installer, who had chapter and verse to quote in his response.

[Steven Fahey]

Another question.
Ventures a little farther into business territory... forgive me if it's too far.

Do you have a period of ownership of the panels before you install them? I'm trying to think through the business model, because it could be set up where the PV installer stocks some panels but has not paid for the units from the wholesaler/importer. And may not stock many but actually order what they need when the install job is signed. Instead, the PV installer sells the installation job, and from those funds pays the wholesaler. In that case, the PV installer never owns the panels, therefore the PV installation company never gains the right to dispose of defective panels. Am I on track here?

I have built this idea based on a discussion with a PV installer here in AB (not the same one who went on about certifications). They told me that they needed permission from the wholesaler if they were to dispose of a defective PV panel in any way other than destroying it or returning it to the wholesaler. And they had never authorized repairs, either.

[Rob Beckers]

Never heard of needing permission from the manufacturer to dispose of a solar panel Steven. Can't see how or why they would care, once the panel is sold.

Regarding ownership and payments: Very few solar panel manufacturers will extend credit these days. Distributors have to pay for the lot before they get it.

-RoB-

[Steven Fahey]

Thanks again!
That's very valuable info.