Serial Defects in Photovoltaic (PV) Modules

Have you experienced repeated faults in solar modules in your PV systems that kept recurring regardless of how many modules you replaced? The team at NAES Renewables has seen how financially devastating and physically destructive PV module serial defects can be. In this discussion, Vice President of Renewables Anne McBroom and Project Engineering Manager Frances Plourde discuss how serial defects form, what distinguishes serial defect claims from module warranty claims, and how to mitigate damage caused by damaged modules.

Have a question? Want to suggest a podcast topic? Want to work with us? Send us an email at powerbank@naes.com. We look forward to hearing from you!

Transcript

0:04

Welcome to Power Bank, sponsored by NACE Renewables, where big ideas, bold conversations, and unstoppable energy collide. We're your hosts, Ann mc Broome and Francis ppl, and we're diving headfirst into everything you need to know, want to hear, and can't stop talking about in renewable energy. Let's get into it.

Anne.mcbroom: 0:28

Thanks for joining Power Bank, the podcast that delves into renewable energy Topics that you need to know and wanna hear today is Ann McBroom and Francis ppl to discuss serial defects. It's a topic that is hot right now. Companies are sitting back wondering what to do, how to prosecute them, and really what they are. Francis, what are your thoughts on serial defects?

Frances.plourde: 0:55

Absolutely. Serial defects are gonna be one of the most important topics to understand in the photovoltaic energy industry, especially as older systems that were installed 10, 15, or 20 years ago start aging and issues in those modules start appearing more and more. Serial defects are considered separate from other aspects of. Photovoltaic module degradation. We know that modules, lose efficiency and degrade physically and electrically over time. That's not what we're talking about when we talk about serial defects. Serial defects refer to specific issues defect or infections in the modules themselves. That. Occur widespread over modules at a specific site or within, a binding group of particular modules that are manufactured and these defects aren't caused by this normal use. Environmental conditions and things like that. These are defects that occur with the modules themselves. So we'll talk about some of the specifics on how the, these can arise, but they have to do with how the modules themselves were constructed or assembled in. Inadequate or less than quality ways that can then lead to significant issues down the line with both with production as well as site safety becomes a huge issue with a lot of these sites that that have serial defects occurring on site. And they can't be prosecuted under regular module warranty They have to be pursued separately, which we'll talk about a little bit later. And do you wanna talk a little bit about how some of these serial defects arise and how we notice them?

Anne.mcbroom: 2:43

Sure, absolutely. We've had a lot of experience dealing with serial defects. On numerous facilities within our portfolio. As we start to service a facility, we start noticing anomalies and some of the anomalies are just aging modules that need to be swapped out with a new module. But many times we notice anomalies that are consistent throughout the facility. And when we start reaching a 10% anomaly rate, we realize, you know, we might have a serious problem here and we need to look a little further into it. 20 to 20 10% to 20% is usually the industry standard to assert a serial defect claim. So as we start noticing these anomalies and we're over the 10% mark, we start documenting, we'll do thermographic imaging to determine just how serious the problem is. Oftentimes we'll see hotspots that appear irregularly. Within a group of modules or throughout an entire Benning Group. And a Benning group is a group that is marked by the company indicating this is a group that was manufactured during the same manufacturing process time. These bin groups indicate that this process was used to encapsulate the modules throughout the entire. Group of modules and the encapsulation process is normally where serial defects lie. Not always, but normally. And in the encapsulation process, the glass has EVA layers and these EVA levels their films that help seal the module and protected from the elements. When EVA is compromised. And it is defective. The encapsulation becomes defective, but there's also the process itself that can be defective and that includes. Heat regulation. If the process is exposed to heat lower than 110 degrees C, this can cause the peroxide to fail to decompose and the module does not seal. There are other issues that can occur as well, such as solder paste defects. When there is copious amounts of solder paste, this can create water intrusion as well as the failure for the encapsulation process to create an adhesion that protects the bus bars from. Exposure to the elements. It's kind of similar to if you have a bathtub at home and silicone is applied to the corners of the tub, sometimes water will get behind the silicone and we start to see events that result from that, such as, you know, fungus and things like this. It's the same concept. The water, ingres in between the layers of the module, and it affects the busbar. It causes delamination. And these events result in arc flash,, ground fault arc fault events. This can be significant. It causes thermal events in the harnesses. It blows the fuses. It can result in environmental. Issues and thermal events in the community. Forest fires especially if there's dry brush underneath the facility, as is most common in the southwestern region where these facilities are installed. These thermal events jeopardize not only the integrity of the system, but the safety of the community. This is a very serious problem and when we start to recognize these anomalies are consistent. Even if we turn a module and the orientation of the J box is up or down it doesn't seem to affect the fact that there's an anomaly in a certain spot of the module. So all of these indicators tell us that there's a serial defect. So in prosecuting the serial defect, we refer to engineers like Francis who will evaluate this data. And do you wanna talk a little bit about your evaluation process when we start providing you with the data? Francis

Frances.plourde: 7:21

One of the main indicators of serial defects that we find in the

Anne.mcbroom: 7:25

I.

Frances.plourde: 7:25

is that of hotspots. So these are areas of the module that are than the rest of the module itself. And one of the main ways that we use to visualize this is thermography or infrared imaging. So this is where we use heat signatures to identify areas of the module that are abnormally hot. And this can be done through aerial thermography. So drone flyovers that capture the entire area at once, or it can be accomplished using handheld infrared imaging that can be used to capture these images. So when we're looking at those images, a lot of our analysis is qualitative rather than quantitative. We're looking for repeated images that show similar patterns on these modules. As Anne was saying, if you have modules that seem to have corrosion or. Evidence of arc fault in one corner or one area of the module, you're going to see hotspots probably in that same region. And if you start seeing that across modules installed at the same site or from the same bidding group, that indicates that there may be a serial defect leading to that We also look at the history of. Electrical or thermal events at that site. So if you're having repeated arc faults that are impacting the inverter of the system, that might indicate that the modules themselves are creating ground fault issues. If you have repeated instances of fires or other thermal events. On the site that may indicate a serial defect is present if that behavior continues even after those modules are replaced. something to note in this case is that since these issues are by definition serial, they are prone to repeat even if those modules that are immediately responsible for or thermal events are replaced because the other modules on site, even though they may not have. Degraded or developed to the point of seriously impacting the site. Those other modules have the tendency and have the ability to behave in a similar way. And so just because you've removed and replaced the modules that are the most obvious cases of a serial defect, doesn't mean the other modules won't follow suit at some point. Serial defects rarely show up in all modules on a site failing all at once. It's usually a cascading effect based on some other factors. But you u but you do end up seeing a sort of domino effect where once you start seeing the defect physically and electrically impacting the site, you're going to start noticing it more and more repeatedly as time proceeds. Ann, would you like to talk a bit about the process of prosecuting a serial defect claim and how these differ from other module warranty claims?

Anne.mcbroom: 10:34

That's a process that definitely needs to be discussed. It's arduous at best. The manufacturers, they issue a warranty with every product they make, but over time, they've become savvy about the exclusivity of certain information, and they will oftentimes issue a warranty. On a solar module that excludes any serial defect claim, the warranty will state that as each module begins to fail they will replace the module with a new one. This creates a conundrum for the site owner or the offtaker. In that they have to de-energize every time a module needs to be replaced. They have to lock out, tag out. The string has to be examined to make sure there was no defects. It's a lengthy process and an investigation needs to occur to determine whether or not the defect in the module caused damage to any other components of the system. So it's very important to look at the warranty to understand what's included. Oftentimes, the manufacturer will agree to replace the modules that are defective in a facility. However, they will not agree to recycle the defective modules. And oftentimes these modules are aging. They're 170 watts, 270 watts, and in those instances, the replacement module that the customer would be receiving at no cost, we'll wind up costing them just as much as if they had purchased new modules that are higher wattage because the cost of recycling the modules in some regions is expensive, especially places like Hawaii or Puerto Rico, Alaska it's expensive to recycle the modules, even to transport them in some states requires a permit. It's just an expensive process, so having a good understanding, having the legal department review a warranty is essential to. Using any material on any site, it doesn't matter whether it's modules or inverters or any type of, harness, fs, whatever, make sure that the warranty is written in a way that's favorable to failure outcomes that we see often in the field, especially with aging assets prosecuting the claim is. It's somewhat different than a warranty claim. A warranty claim, they have a form. The manufacturer has a form on their website with information about prosecuting an individual warranty claim. So you know you'll have 10 or 12 modules on the form. The form will go in, they'll replace the 10 or 12 modules. A serial defect requires data. It requires investigation. It requires testing, and those results have to be coupled with a lengthy form, a spreadsheet, serial numbers, photos, instances of thermal events. And then records of every anomaly on the facility with a requirement of 10 to 20% depending on the manufacturer. This can get expensive because when there are 10 to 20% of anomalies occurring in a facility, the facility is not safe to energize and many fire marshals will require derg. Of a facility until it can be remediated to correct these anomalies, especially if there's been a thermal event and the fire marshal is aware of that event. So preparing this information can require a flyover, energize flyover de-energize. And then testing, IR testing as Francis spoke about the Ivy Curve testing, the IR testing. These are all important aspects of the presentation of a serial defect. The more data you have to support your claim, the better chances you have of the manufacturer even entertaining the claim. And in addition, the more data you have. The shorter the duration for settlement on your claim. Many manufacturers will take a year, two years, three years to settle a serial defect claim. This can have serious implications to the power purchase agreement. The PPA has requirements for the offtaker to provide a certain amount of output to the grid, and when these facilities are de-energized for long periods of time. Due to these issues, it can be a financial disaster for an Offtaker and Francis. I wanted to know what your opinion was on cannibalizing to help keep the site energized with the modules that aren't defective or showing any signs of defect at this time, what your thoughts are on cannibalizing, and then de-energized certain strings of the failing modules.

Frances.plourde: 15:54

Absolutely. All define cannibalization. For those who may not know, that involves moving modules. From the rack in which they're installed to another area to fill in gaps in the array to allow for entire racks or entire strings to be fully replaced with other modules. Basically you're consolidating the existing modules on site and then replacing full arrays or full strings all at once. This makes the replacement process a lot easier and a lot more efficient. Since we know that these issues are. Going to recur with serial defects. It's not a question of if the other modules on site will fail, it's a question of when we don't recommend cannibalization for long-term solutions for serial defect issues, they may be able to provide a stop gap, but especially in cases where the serial defects are leading to fires continued energization and utilization of that site to generate energy is really a safety issue, and it can become an issue even within the local community. The fire department may become involved, the city government may become involved if it's known. These modules have the tendency to create thermal events and fire related issues. And so because of that we don't really recommend cannibalization and. Consolidation of the modules with the known serial defects on site. Because it doesn't solve the problem. It just removes the worst offenders the worst offenders of serial defects, with those modules. But it allows the other modules that are. Still on site to continue to pose safety risks and to continue to move closer and closer to catastrophic failure as a solution to this issue. So if you've established that you have a serial defect in the modules on your site, once you've hit that 10 to 20% number that we've talked about, we really recommend full module replacement. This is where it can be tricky. In the process of prosecuting a serial defect claim, there may be different results from that claim. As Anne said, these take a really long time to pursue. And so you may not be able to perform a full module replacement in a timely manner, but that's what we really highly recommend. So especially in the case where a module manufacturer has resolved a serial defect claim by either perform, either providing. Replacement modules or providing the money to purchase replacement modules. we do believe that at that point, full module modular replacement is necessary to make sure that the system is not just going to be able to recoup the energy production. It should be hitting based on the PPA, but continues to remain safe to use and to operate. we'll be discussing in a future podcast how these module replacements are performed. It's a. Very specialized process but to answer the question, we really believe that full modular replacement is a significantly better and safer solution to serial defects than just cannibalizing the array. We understand it's a significant expense, and especially if you've been facing losses of production and equipment because of the serial defects, you may not be willing to incur that much more of an expense, but we really recommend that for long-term safety and longevity of this site. Do you have any final thoughts on this issue, Anne, before we wrap up?

Anne.mcbroom: 19:40

Well, my main thought is that I'm excited to know that there's an additional podcast coming up regarding the study for replacing these modules. I know it, it's a time consuming process, and from the reports I've read, Francis does it better than anyone I know. So I think discussing the topic with. Would be very intriguing, especially coming from France. So excited to listen to that. Knowing that it's coming up is, is a great segue into what really happens with the modules and how we determine what's necessary for them to be replaced. My final thought is that, you know, be smart about your purchases. I know that the initial. CapEx costs for modules are a significant factor in determining the budget for a project. But in the long run, these modules, they have warranty implications that can last decades, and it's not something that should be taken lightly, especially for the integrity of the facility. The. The community safety and the mutual agreement in the PPAs, I think that looking at them, having legal review them understanding which companies offer the best warranties, because if you're saving on your upfront cost, you're going to pay much more down the line. Just take the time, do your due diligence, and make sure that you're selecting a module that's going to provide you the output that you need for the longevity of your PPA.

21:19

Absolutely. Thank you so much, Ann. Thank you so much for joining us on today's episode of The Power Bank, sponsored by NACE Renewables. If you have any questions regarding the topic of our discussion today, or you would like to reach out to us about special projects for photovoltaic sites, we would absolutely love to talk with you. You can send us an email at Power bank@nace.com. Thank you and keep powering on.