Status Update

Apr 24, 2020

Hello and welcome to the webinar, Innovative Approach to Assess Solar Plant Health and the Role of technology in protecting assets. I'm Luc Brett from Reuters Events. This is one of several pieces of work we're doing on optimizing the operational phase of the solar lifecycle. Do get in touch if you're interested in participating in any of our digital content over the coming months. My email is lukeleuenergyupdate.com. There are over 1,000 of you signed up today, so thanks very much for the great response and thank you in advance to our panelists for their time. Just a brief bit of housekeeping before we begin. This webinar will last an hour and is being recorded and we will send you all the audio recordings and presentations within a week. You have the facility to ask questions through me as an organizer, so make sure you have access to your computer. The purpose of today's session is really to take a closer look at the barriers when operating and maintaining SODIPARKS and to discuss which technologies are being used to optimize this. Joining me today to address some of the issues, Jacqueline from Allianz Global Investors, Andrea from JinkoSolar and Lucy from DuPont Photovoltaic Solutions. If at any point you want to ask analysts a question, simply enter this into a text box and we will try to get to it during the Q and A. So without further ado, Jacqueline, who will be moderating the session, do fire away. Well, thank you, Luc. I'm very happy to be here today. I would like to introduce this session with a quote from our CEO, Andreas Zuteman, who once said, people go where they feel welcome, but they stay where they feel included. And this is my motto today. There is no cluster silo. We are all part of the value chain and each of us has a role to play. So bear with us, contribute and let's start a constructive discussion on how we can all together as an integrated and deliver quality and performance. So welcome, everybody, and let's start with presentation from Andrea from JinkoSolar. Thank you very much, Jacqueline, and look for the very nice introduction. Also very happy to participate to this webinar today. So Going to start with our presentation. As Jacqueline mentioned, I think the topic it's really related to how to make sure that PV plants operate and perform in the best possible conditions. And of course, to reach that the journey starts from a junk of silicon material probably to produce some technology that's then put in the ground can really perform at best of the condition and put in the condition to perform in a very reliable and durable way for a very long time. That modules are really supposed to stay in the field for long, long time. So from the manufacturing point of view, it's really challenging to make sure that of course the modules will perform according to expectations and not only because of the warranty says that because but because of course we need to have technologies reliable and able to sustain the business plans and the development of competitive cost of electricity and energy generation in general. From the manufacturing point of view, of course, Jinko is since ever focused on keeping high quality components, high quality technology, reliable of course and mature. So historically, Jinko of course had a very strong evolution on technology starting since the beginning from R and D. And historically, of course, we remember Ginkgo was producing, of course, cost effective polycrystalline technology. But modules, thanks also to our R and D investments and efforts even at large scale production. We are talking about the production volume of Ginkgo plant for this year of almost 20 gigawatts, focused on mono PERC high efficiency cells with, for instance, one of the world records last achieved already above 24.5% cell efficiency. Of course, this is a target of course to increase performance of modules starting from clearly the efficiency and the nominal power class of the modules. And that's again just the tip of the iceberg when talking about quality and reliability and performance of a PV plant. The journey starts much far away as I was telling, because especially in a production vertically integrated production like the one from Genco, we start focusing on technology and quality since when we cast ingots for production, then cutting them into wafers, producing cells and modules finally as a fish product. These vertical integration of course give us the possibility to control not only the price of the cost of the production, but also the quality of production. And this is where the quality value chain starts, because again having a module that let me stress out again have to perform for 25, 30 years in the field. Of course, these fulfillment is achieved since when the modules are produced with high quality components and when production is really controlled from A to Z to make sure that the modules do not degrade for instance further than what it's normally expected. And again, not because only the warranty says that. In terms of technology then, just for instance and technology and innovations, we saw in the industry and in the market not only driven by Jinko, but in general driven by the fact that the size of the PD cells is really increasing right now and the target is to go towards even larger PD cells. Clearly, this sets a challenge in terms of reliability and not only in terms of performance, which is for instance the fact that a larger cell produces more current. This is of course very good from the performance point of view. The module power class can really increase because the losses at module level are really significantly decreased. Just to compare, the same module made with the same cell efficiency in the format of a full cell or a half cut cell can really have a gap of 2 power classes even. So we are talking about between 8 10 watts per model difference again using the same cell efficiency. But of course, in terms of reliability, this can be a challenge if the for instance, the current or the energy dissipated on a module or on a cell because of a hotspot, for instance, happens. And in a full cell format, we have the potential risk of overheating the cell to a critical limit, which could be somehow dangerous for not the cell itself necessarily, but for instance, encapsulating material, the polymers used for the backsheet or the encapsulating of course in general of the encapsulation in general of the module. So talking about numbers for instance and hotspots, a module with a full site configuration can really develop easily hotspots, but not easily unfortunately, but in some situation, in some scenario can really have developed hotspots far beyond 100 degrees Celsius. This is really, really dangerous because of course you can imagine the stress the thermal stress that is induced on the polymers, on the plastic materials and this is potentially a threat, if we have this situation. In a half cut cell configuration, the modules, of course have a the cell have a different shape, different format, different interconnection and a different area. So the energy dissipation that happens on a half cut cell model is significantly lower and enough to protect the model even in this of course unwanted or dangerous scenario that unfortunately happen actually often and more than what we would like to see. But we will see later also in which cases and that's also related to the operation and maintenance side, which is of course the topic of today, how the hotspots can really develop from really unexpected or underestimated situations and why is it important to have for instance, as in this case, hot cut modules configuration to really significantly mitigate the risk that we have on not only in performance, but more importantly on the reliability of the models. One more innovation that was introduced in the last years, of course, apart from half cut cell is in the increased number of busbars to not only increase the power class of the modules and the low light performance for instance, but also to mitigate in terms of reliability the potential impact of micro cracks. On a half cut cell module is very straightforward, understandable by the fact that the geometry of the cell changes and the potential developments or path of a crack is reduced by 50%. This potentially decreases the disconnected portion of the cell surface by 50% accordingly. So potentially the impact on performance reduction that we have on a half cut set, it's also reduced thanks to this configuration and to this different cell interconnection. And in terms of multi bus spur, for instance, technology or multi wire as the technology is going towards like in our Tiger series, newly developed and launched very recently, is the fact that by moving from 5 busbars for instance up to 9 busbars or 9 multi wire interconnection, This also significantly reduces the potential impact of micro cracks. And again, this is not only for power class of modules and the efficiency of power class of modules in terms of nominal values, but in terms of operation of the modules in the field, because the majority of micro cracks as we know are unfortunately not produced or fortunately for us not produced in production or doing transportation even, but many, many cases during the operation and because of the vibrations or mechanical stress or thermal stress that the modules have to go through during the operation in lifetime. Talking again about our new Tiger series and the developments not only in terms of technology, but also in terms of reliability. The special shape of the wire, which is not a normal round shape, clearly is focused to increase the reliability of the modules and to decrease the potential damages that could happen on cracks. Clearly, the cracks that could happen on the sets, sorry. Clearly, the fact that there is a metal connected to a silicon material created creates some mechanical stress, for instance, caused by the different thermal expansions or thermal behavior of the 2 materials into the laminate, which could for instance very simply generate possible cracks on the cells, which are all fragile or very thin materials, thin slices of silicon, which are can be significantly impacted by thermal stress induced by metal wire or a metal busbar, metal ribbon. In fact, that's the ribbon in this case is much thinner in terms of mechanical stress, of course, helps to reduce this potential impact on the cell. So the technology development is not of course only focused on the increase of power class of modules or efficiency of the modules, but especially also on the reliability of the interconnection and ultimately of the module overall. And for instance, even the fact that at the overlap of the Tiger modules, the overlap cell area where the cells are slightly almost touching each other, there is a cushion or a buffer where the EVA is playing this role of protecting not only the cell in terms of encapsulation, but also in terms of mechanical resistance or protection against stress against cracks or possible damages. And of course, if we talk about reliability and long term durability of modules, we know all how important is the role of the encapsulation and especially of the backsheet. And of course, the fact that using the possibility there is a possibility to use many different components and many different materials for the backsheet, of course, opens a very wide range of scenario and behavior of the modules in the field. We will see that later during Lucy's presentation and analysis that DuPont did in the field of the modules behavior. And this is just summarizing here in this slide how the fact that Tethro based budget actually do have really the lowest possible failure rates measured in the field, which is of course the reason why we use that material in particular for the production of PV modules. And all of course it aims to increase the profitability of the PV plants. As I said, the fact that the modules have a high power class or high efficiency is just the tip of the iceberg. Downstream, the modules have to operate reliably and durably for a very long time. And again, in terms of value chain or quality value chain, we try of course to cover as long as possible the chain, but of course there is a limitation as manufacturing as a manufacturer that there is steps that are not in our control. But of course, we always try to cooperate with the downstream markets to guide EPCs or investors or in stores in a way to make sure that the modules really are put in the condition and even stored or handled or installed, operated, maintained in the best possible way and the appropriate way to reduce possible damages that might occur. Even a very simple aspect in terms of storage, we saw unfortunately in many cases even distributors still stuck in 3 boxes of modules for instance, 1 on top of the other. This is a possible damage for of course the box that sits at the bottom. And of course, despite the even the manuals or any guidelines clearly states that there is still, of course, unfortunately distributors or somehow part is not really probably underestimating the potential impact that this generates on the modules. And even in terms of handling or care of the modules during the operation, for instance, we all know that we don't have to step on modules. We saw later a couple of pictures showing that actually not everyone is really doing that. But again, this is not to blame or not to point the finger against someone that is probably not doing things right, but it's just to state how important is also to keep the manufacturer involved even during the operation of the sites to make sure that the modules really perform according to expectations and to follow the guidance and the suggestions that the manufacturers of the modules like in our case can give to the operators to make sure that the modules really perform in a reliable and durable way. I was talking about cracks before and how important is to mitigate cracks on the modules. I mentioned that cracks happen during operation on the modules. We know that of course even the wind pressure, the vibrations on modules generate cracks because of the mechanical stress that it's induced on the silicon wafers on the silicon cell. But clearly, if we step on the modules and I mean in this picture is I think it's clear that someone clearly didn't follow the rules that I will show you in the view slide, but this directly induced cracks on modules and it's even visually possible to spot these kind of damages even with a simple infrared inspection and not really necessary even in some cases to go for airbrush reminiscence when the problem is so high that the interconnections of the cells are really damaged for instance and the cells are so cracked that can be redeveloping hotspots. And even during operation and maintenance, we will see later also in terms of cleaning how important is to pay attention on the way and the systems and the processes that we apply for the cleaning of the modules to make sure that the modules are not damaged. In terms of installations, we all know there is a standard that an IEC standard that sets that for instance, the connectors of the modules should not be plugged with different type or different shapes or different brands of connectors. This is a regulation that is clearly not probably mandatory from the manufacturing point of view, but of course it is required to have an IC certification for the installation. And it's not rare to see in the past installations made with even MC3 and MC4 connectors together, which is clearly not working well. And we see at the center of the pictures here what happens if that is done clearly because the connectors, if they're not plugged properly or plugged with different type of connectors can really melt. And this is a very simple thing to do and very easy actually rule to follow during installation of the PV sites, but really can create potential losses on the PV operation and operation of the sites and can really increase losses on the sites if it's not full. Talking about hotspots, clearly, we know that modules have to be cleaned. Now the question is how often? Many times we also have questions from customers, UPCs or operational maintenance companies, how often the modules have to be cleaned and how can we clean the modules with a dry system, with a water system and so on and so forth. So of course, every case, every site, every installation is different. So it's there is not a general rule, but it's clear that when an installation is put in condition to develop hotspots like shown in this chart above 100 degrees, we are not only reducing the performance of the installation, but we are significantly hampering the reliability. These modules were of course on a very dusty area, where workloads were done very beside the peak installation. The modules were completely covered by dust and the modules as you see here were really developing hotspots above 110 degree Celsius. This is really dangerous and the modules were already bubbling. The EVA was already bubbling and creating some kind of start delaminating the modules. And again, the problem is that it's not only losing power and energy and yield of the plants, but really potentially damaging the performance of the reliability of the module. I was making jokes about the fact that we don't have to step on modules and in my experience it happened also that for instance, of course, we suggested to clean the modules to the customers because they were dirty because of some dust accumulation and of course, clearly cleaning them carefully, so we say. I think the operators probably took our words a little more a little too strict way, because they were so careful that they were really the operator were really jumping on the modules to clean them centimeter by centimeter. But clearly, the problem is that, yes, the modules were spotless, really brilliantly clean, but we didn't do any electro emission test, but for sure, the cells were most likely damaged because of this operation period in this way. Also in terms of cleaning, it's interesting many times and it happens also in our experience to see how modules can be looking perfectly clean. The surface maybe it's really looking clean and homogeneous. But in reality, the thin layer of dust that it's accumulated, it's potentially not visible by eye or not so obvious that it's like shown here in top right picture, visible by eye. But if we go for an extra sorry, for an infrared inspection, for instance, in this case, and the customer was, if I remember well as in this case probably thinking of potential damages of the modules or unperformance or problems with the modules. We with an infrared inspection, we clearly identified the fact that and they of course, they confirm that they clean the modules with water jet. And the water jet traces were really clearly visible on the infrared images here. And this is clearly not a good way of cleaning modules for instance, because the water jet high pressure can really generate strong vibrations on the modules, which can really potentially damage the sensor. So clearly, again, it's important also when cleaning or operating the sites or doing any modification to the installation or operation activity, maintenance activity. It's really important to keep the suppliers of the components involved or to ask for confirmation if any doubts to make sure that the operations is really carried out in the proper way, if there is no indications in the manuals or guidance that the manuals are giving or the component suppliers are giving. So to summarize clearly, we all talk about the RCOE, IRR and how important is of course to make sure that the energy production is high and the modules and the BOS costs are reduced as much as possible and the module efficiency is high. But of course, we always have to keep in mind that the quality value chain is much longer than what the manufacturers can do in the factory and how much efficiency we can put into model. And of course, we also have to keep in mind how important is the operation and maintenance activities and to follow the guidelines and to ask for support to manufacturers as well when needed to make sure that the modules really perform in a durable and reliable way for a long time to make sure that the system performance is the highest possible. Thank you very much and I give back to the board to Giulia. Well, thank you, Andrea. Personally, I find it very bold, I mean, that a motor manufacturer comes on stage and not only acknowledge the defects coming from motors, but they do address them and how they do address them. And I think it's exactly what I like about the presentation from Andrea that it highlights the complexity in the PIV industry. There is this common belief that if the sun shines, the power plant is producing, but it's not that easy. There are so many factors and components which have to come together in order for those motors to properly function and deliver their promised output. And when it does not happen, every technical interface can be a source of underperformance. And I can tell you everything that Andrea showed in his presentation, I have seen it. So I think it's something maybe we should reflect on. I think now it's the perfect transition to Lucy's presentation on sharing DuPont's experience and expertise. So I'll leave it to you now, Lucy. I'm trying to do things in the right order, unmute, present, so I hope everybody can now see my screen. So I'm going to talk to you a little bit about some innovative approach to assess solar plant health. But before I get to that, I need to turn the page and it's not doing it. Let's do it that thing. It looks like I have no control. Luca, I need your help because I have no control there. Hi. Just please just try again quickly. You are the presenter, so it should be working smoothly as practiced. Just try one more time. On full screen. There we are, they appear now. Thank you, Luc. When I meet somebody, first of all, I'd like to know where they're coming from so that I can understand better where they're going. So this is where we come from and in particular where I come from. I started in the PV industry in 2,009. I spent about 3 years doing prototype making prototype modules. You would never believe what I've done. And then I went to the field and did some panel inspections to understand the degradation process on panels. Our field partners were developers, utility companies, universities, O and M companies, service providers and so on. And they allowed us to collect statistics on about 1.8 gigawatts of panels spread over 3.55 installations. What we learned from this is actually surprised me about 1 third of the panels we inspected showed a visual defect. That's a pretty high number. Amongst the visual defects you see, for example, broken panels, water ingress, EVA yellowing, delaminations at various interfaces, some solder ribbon corrosion and I probably missed a couple. There are also some invisible defects such as PID, which is only visible with the MOREN IV testing. And then you have also some problems with defective diodes and so on. Now the potential impact of all those defects is you may lose power and that's notably what hotspot will do PID, LID, light and temperature induced degradation and various types of cell degradation involving shunt resistance and series resistance. And then you have also some safety implications. In particular, when you have backsheet cracking, then you will suffer from a major safety problem. So I was trying to think about what tools I had in my toolbox and in which case I should use which tool. I'll take an example there to illustrate the multimodal approach. Say you have thermal imaging, you can even do a visual inspection, some limited lab analysis, You can do IV testing in the field and then you can of course look at your historical trends from the archived data in the monitoring system. I take the example of PID. What do I need to have so that I know I've got PID? When you give me a thermal camera, I'll be able to tell you if you've got PID. That's all I need to tell you you've got PID. However, if you want to put a system fix in place, then I need to also see the panels. And then I will tell you if you can recover your PID or if you can recover only part of your PID. To know the extent of the problem, really, you need to do IV testing. So this will give you how much power you've lost. The IV testing only gives you the data for today. It doesn't give you the data for a months ago or a year ago. So to determine how much power I've lost over a period of time, I will need to look at your historical trends. And then I've used every tool in my toolbox to diagnose the problem and quantify the problem and determine the potential for recovery. So that's where the multimodal approach is born. This multimodal approach doesn't apply to every type of defect. So you might actually use 1 or 2 or 3 of your tools in your toolbox according to what you really want to do. So I'll give you another example of a portfolio assessment we performed last year. We had 40 plants and the basic assumptions was that the plants were performing. Question is, are they really, are they performing okay or are they underperforming? So first of all, we need to set an expectation, how much is a normal degradation and even that is a pretty tricky point. So I decided to base myself on an NREL publication and this NREL publication said that angles between 10 years tend to suffer from 0.7% degradation per year. So I wanted to be compared to my year group in the 0 to 10 year group. So now 0.7% degradation is my expected degradation. After performing several measurements, various types of measurements, this is the picture we get. We've got a total power loss and we've got the number of years of operation. Your dotted black line there is your expected degradation and we can see that only 4 installations performed to our degradation criteria of 0.7%. Now there are various reasons where we might have got to that stage. First of all, soiling and vegetation growth. We applied some corrections to our data to make sure we didn't take in consideration any soiling or any vegetation growth. So this data is clean of soiling and vegetation. Now you may also suffer from system losses. System losses include ground faults, inverter problems, cable problems. Sometimes you will suffer curtailments and network availability. The scope of our work was really to determine the power loss at the panel level, so we also eliminated the system losses. So the picture you have there is only linked to panel level losses. I have highlighted some of the losses in the previous slides, so I will not go through them again. Now we look a little bit more in detail, where our losses are coming from. Well, we performed some thermal imaging and we were able to determine the amount of disconnected panels here. You see some installations here suffer from high degree of disconnect. Potential reasons for disconnected panels of strings are blowing fuses and faulty connectors. These two reasons are pretty easy to fix. And then on top of that, you might have ground fault problems, the famous riser problems. On a couple of installations, we saw some fire damage. And of course, you've got the reasons that are beyond your control like weather damage. And finally, some £40. We decided to discount the disconnected strings here and really get to how are the panels performing from those that are connected, how well are they performing. So there we are. We get from the graph on the left hand side to the graph on the right hand side where we exclude the disconnected strings and panels. The picture is much better, but only a quarter of our installations are performing to our expectation of degradation. So that's a lot of degradation. Amongst the causes for degradation, this was a very wide portfolio, so we saw very wide problems on this portfolio. So some of the causes, we had a couple of installations with many, many broken cells and the power loss from there was obvious. We had also a couple of installations with early PID problems. Early PID problems can be spotted very easily with thermal imaging. Like at the end of the strain, you see a very mild thermal signature, which is very indicative of early PID. And in some installations, we also had pretty high optical losses. The optical losses may come from delamination problems in front of the cells, but they may also come from EVA yellowing and other types of optical transformation in front of the cell. So what did we learn? Well, actually these installations delivered revenue. So they were under pretty good feeding tariff for that time. The installations were also reported as having backsheet problems. But be careful, backsheet problems usually do not yield power losses. The reason for that is you may suffer late inverter starts or tripping in bad weather and these are all times of minimal production. So in fact at the system level when you look at your production data, it's fairly rare that you will see an increase in your power loss due to backsheet problems, cracked backsheets. But you might have to put more effort into maintaining your operation with this type of problem. Still, not having a cracked backsheet will mean that you're leaving potentially bare wires exposed. So you have a duty to make your installation safe. Now why didn't we detect this power loss before? In fact, we did detect it before. We were called to investigate on this portfolio because there was an inclination that this portfolio was not operating properly. So our data is a little bit skewed. It wasn't a complete surprise that it was underperforming. Now the reason why it's difficult to assess the amount of underperformance is, first, the performance ratio. Everybody loves the performance ratio. But it relies on accurate assessment of erasions and temperature. And weather station tends to suffer from misalignment, soiling, braking, degradation and drift and they usually don't get the tender loving care that the panels are getting or even the same GLC as your inverters. Then we've got a complex system. We've got multiple components and each of them may dysfunction or malfunction. We also have a system of optimization on-site. So the maximum power point tracking is an optimization system. We might even interlink your inverters so that they one of them will capture all the energy produced of all the others at the beginning of the day. That's an optimization system. So all these malfunction functions and the optimization system mean that you've got a very complex system to analyze. And then this is all done in multiple conditions and ever changing conditions of vegetation and soiling and shading. So indeed, we measure a lot of data, but how to analyze this data is very complex. Also last point, these plants were between 6 11 years old. They had a monitoring system, but the quality of the data was fairly poor. Now I would say the quality of the data for those plants was actually not out of line compared to other plants of that age. So there are some challenges for those times that were pretty difficult and complex to solve. So I'll leave you I've got a couple of minutes, I think. I'll leave you with a little story. Many years ago, I wasn't working in PV and one of my customers had a production problem with our product. So I had to go and see him to check what the problem was and solve it. We started production and the problem didn't show. And we waited all day watching production and the problem didn't show. So with the customer, we decided, okay, what is the information that you need to send me when you have this problem, how fast and which kind of lot number and clear descriptions and photos and I'll come back when the problem reappears. And I went into the office and I thought, okay, my product was in spec, It wasn't like borderline spec. It was well in the spec for every parameter that I was measuring. But that product still created a problem at the customer. That means that somehow I was not measuring something that was crucial for my customer to be operating. And that's what KPIs are about like key performance indicator is that how do you assess the performance of the product. It might be something that is touchable that you sell, it might be a service that you sell. So your KPIs will help you along the way to determine the health of your plant and maybe how to make it work better. Diagnosis is part of the cure. So I want to leave you with those thoughts and I hope there will be some questions. Back over to you, Jacqueline. Thank you, Lucille. I find the presentation from Lucille interesting, and I agree with her. We have accumulated over time a huge amount of data, and it's true that we do not always take the time to look at them, to run analysis in order to detect eventually defaults or maybe potential optimizations. And I think it's the next milestone in our industry, the digitalization topic. And I would like to come back on the introduction from Lucy. She explained where she came, where she was heading to from the laboratory to the PV fields. And it's exactly what I would like to come back on that how did DuPont develop its expertise in the PV industry. Originally, they provided components for the production of back sheets. And actually, they just need to know how their back sheets With the matches, they match it, they match it would behave compared to other materials. And they started to ask customers. Then they directly talked to end users and they went on field. They inspected PV plants. And over time, they accumulated data, which thankfully they are sharing with us today on all the defects that they are. And my take away from what Andrea and Lucie have presented is really following. You purchased a model over 20 years, 25, if not more. And if you wanted to age well, take care of it, maintain it properly and perform well-being check the same way you do it for any other asset, could it be your car or your house? Now I think we will start the Q and A session. I think there were already some interesting questions about how to detect the micro cracks, what would be the different instruments, different methodology? I don't know. Lucie, do you want to take it over from me? Yes. So Andrea will be able to answer that one as well. But micro cracks are pretty tricky and the wording of the defect is important there. A micro crack means that you've got a crack in the cell, but you haven't disrupted the connection on your cells. So basically, your very finger lines there are not interrupted. So micro cracks pretty much amount for no power loss. You can detect them with electroluminescence. You cannot detect them with thermal imaging because for thermal imaging, you need to have full blown cracks. That means finger line interruption and then that will generate some hotspots. But yes, you can detect them with electroluminescence. Thank you, Lucy. There is another question on the correlation between hotspots and hotspots and Soli. Andrea, would you like to answer that? Yes. Thank you. And yes, of course, it doesn't happen always clearly that of course Moses develop hotspots and desoiling is one of the causes, well, probably one of the most common causes of hospital development unfortunately. It happens when of course modules or cells are not homogeneously or somehow partially shaded or partially soiled. But the heavy soiling early tends to develop hotspots on cells on the modules because of the current dissipation or energy dissipation because of the lower activity of the shaded cells. That's something that has to be normally avoided and it's normally tolerated in a normal soiling scenario, in a normal tolerable soiling losses scenario that are affecting naturally most of the installations. But when happen in a heavy way like in the pictures I've shown during my presentation, clearly the risk is there and the interest from all is clear to avoid or to solve those problems in the fastest possible way to reduce possible damages to the margins. Thank you, Andrea. I personally have a question for Andrea. You showed us the different kind of defects on the motors and how you mitigated them. And I was just wondering how do you get this information from the operation field? Since you said yourself, once you sell the model, everything is out of your account, how do you get access to boost that on field and how do you actually integrate them to 2 things, to your production lines and to your commercial process to your contracts basically? How you sell them and Very broad topic and how to be a short answer, but let me try. They are clearly, of course, the influence or control that the manufacturer have on the PV modules operation is very limited downstream. But of course, we let's say that in general, if module is transported, operated and installed and operated properly, the potential failures are really, really low. We are talking about historical data that we have from our mass production of below 1% of failure rates on PV modules. So we are really talking about small, small volumes of general failures that can happen on mass production. Of course, that's when modules operates in a proper way or models are operating in a proper way. That's why it's important to keep us or to keep the manufacturers somehow involved when something seems to go wrong with the PM modules in our case. And of course, we also learn from that. I mean, the solution of the half cut cell was just an example, for instance, to see how nicely the technology development had also to mitigate, for instance, the outperformance phenomena that might happen during the lifetime of the PV modules. But even in the next generation of PM modules, we are continuously learning and improving also the materials and again also the history that we have on back sheets material that was used in the past or polyamide or PET, we learn a lot about how to prevent or avoid failures or to increase the durability of the beam modules by selecting the correct components for production. Thank you, Andrea. I also have a question for Lucie because as an asset manager, of course, I'm extremely cost conscious. So I was just wondering, you presented this 360 approach. What do you have any idea of what which costs are involved here? Could you come up with a figure or just a range? And what would be your recommendation on this 360 approach? This how would you say? Is there a good time to start doing this health check? Or is there I don't know, what is overall your approach on this? It's a hard question to answer, Jacqueline, because it actually depends on the scope of your project. So if you want to go on all around health check, you might be more detailed in the case where, for example, you want to purchase a plant. So the level of investigation will vary according to the scope of the project. So no, it's difficult to give you a price. This is a project based price. And basically, it's we need to talk more about value in terms of trying to put some kind of financial numbers on this activity. Value of the asset, So this value of the asset, if you underestimate the value of the asset, you have a problem. You should always try to help check with every change of ownership. And I take change of ownership in the broad context. So when you change, for example, when you do the acceptance test, for example, so when you go from an EPC contract to an O and M contract, it's useful to know the health of your clients. But even with cases where even a change in the insurance contract, it is useful to know the health of your plants. So your old insurer will ensure a certain number of things. But if you have potentially pre existing problems and then you change your insurance, your new insurer will not insure you for the pre existing problems. And it might be that you only used a couple of panels with a cracked fact sheet and this seemed to be a sporadic problem. So you didn't think it was a widespread problem, but your new insurer will say, well, it may not have been widespread, but it's the same defect, so we will not ensure this defect. And then you run into problems. So any change of ownership, whether it is contract based or whether it is really owning the asset, it's useful to know the health of your plant. Yes, that makes sense. Thank you, Lucille. There is an interesting question here. How do you detect and quantify PID loss in an operational plant? And could you expand on the thermography? Would you like to answer this one as well? Yes. PID has actually now become a pretty simple problem to diagnose and quantify. If you stay in the field, it's easy to quantify and diagnose. So basically, diagnosis just you've got the disease, but I can't tell you how serious it is. So you do that with thermal imaging and you will tend to compare your springs, the start of the string with the end of the string and you will derive a pattern of heating with thermal imaging. So that's the diagnosis. But at that stage, I can't tell you how serious it is. I can only tell you how serious it is with IV testing. And this will tell you how serious it is now, okay, not as serious it's been for how long. So your historical trend will give you another clue about how long you've lived with this problem and potentially on the evolution of the problem in the coming years. Thank you, Lucy. I think there is another question for you and it comes to my questions as well. Ravi is asking for 100 megawatt big portfolio, what is the time and effort to conduct a full 360? Again, it depends. It depends. If you look at the 10 plants, 10 megawatts, the turnover could be fairly fast because we've tried to automate the process as much as possible. Depending on the value you want to get, but also on the circumstances you want to get the data under, you might decide to do only a sample sample test of IV, for example, which could make sense. So you would do 100% thermal imaging and then you would do say only 50% or even 10% depending on your thermal imaging or the IV testing. So you can actually turn around this type of data at 10 plants, 10 megawatts, a portfolio of 100 megawatts in a pretty short time. If you've got only one plant at 100 megawatts, it's even easier. It's more boring for me, but it's easier. So I guess you could work that one around. Let's take the 2 scenarios. You could work around some data in about a month on 100 megawatts on one plant. If you need to manage several assets there and do the 360 on several assets, it might take you 2 or 3 months. It depends how many assets you're talking about. Yes, that makes sense. The logistics is very important also in assessing how long it's going to take. Thank you, Lucille. I have another interesting question here from Constantin and I think it's going to be rather for Andrea. What is your view on UV Fluorescence test versus EL test? Interesting one. The first one is, yes, somehow probably starting to be used more commonly in the last period. The information we can have from the 2 tests or 2 methodologies are clearly not exactly the same. So there is, of course, advantages or disadvantages on using fluorescence or electro luminescence also in terms of feasibility of the test or speed of the test. I think the interesting thing of fluorescence is that can tell somehow part of the story of the cracks. It can tell in some cases when a crack happened, which is not possible to tell from electro reminiscence test. Probably, again, to when it's probably necessary or possible to understand a little more about the history of the cracks developments, it can be more effectively used for this kind of analysis. I think that remittance is probably more common because just it was mostly used in last years compared to fluorescence. But clearly, it's also a very good and useful tool to use even on-site. And I think the limit of lateral remissions was in the past that it was not possible to use it in the field. But now there is even portable tools even with drones or portable machines that can really enable to do a Latremia sense very easily and quickly also in FID. Thank you, Andrea. I have a very interesting question from Carline. How do you detect backsheet problems during the preventive maintenance? Lucie, would you like to answer that one? Yes, sure. Backsheet problems are usually in 3 categories. You might see back sheets yellowing either when you look through the glass or when you look at the back of the back sheet. So that's a pretty easy visual problem to see, not easy to photograph. So you need a white sheet to try and show the amount of yellowing. And then you've got 2 other problems which are serious problems. These are backsheet delamination. They look a little bit like a bubble strapped when you look at the backside of the panel. And then you've got backsheet cracking. Now the cracking, you could see directly from looking at the back of the backsheet or you might have to have a backlight behind your field of observation. So you would put a torchlight behind at the front of the panel and you will look from the other side to see in a layer cracking which will lead to water ingress also. So yes, patch sheet problems are pretty visual problems. When you have them, you can see them. And then in an operational phase, you may be able to see your backsheet problems if you've got ground faults on your inverters and inverter tripping. Thank you, Lucie. I think we will take one last question from Christian and it's going to be for Andrea. Does it include hotspot PV Motors and to which extent? Sorry, I didn't hear the first part. Can you repeat that? Does shading cause hotspots? Yes. Yes, of course. Yes, clearly yes, fortunately. It depends on what kind of shading we are talking about. Normally, fast shading like caused by multi row shading on shed installation or normal ground mounted installation is in the order of few degrees. We are talking about probably in general condition between 5 10 degrees Celsius household, which is totally tolerable for PE module. But if we talk about very near shading caused by for instance, leaves on the modules or bird drops or even soiling itself, it can be of course considered kind of shading, then we see that those scenarios really or obstacles very close to the PV modules on for instance on rooftops like chimneys or poles etcetera. These kind of shades can really increase the temperature of the cells quite a lot, especially if it is a small area, which is not triggering the function, the bypass function of the diodes that are installed in the junction box. So that's this transition part of functioning of the module when the diodes are not acting to protect the cells and the modules and the cells are partially shaded in a very near shade scenario, then that's probably one of the most difficult situation and when the modules can redevelop hotspots of tens of degrees Celsius unfortunately. Thank you, Andrea. I think we have reached our limit. Luc, do you want to close the presentation? Absolutely. Thanks a lot, guys. Excellent job, all presenters and panelists, Jacqueline, you did a great job steering the conversation. And Andrea and Lucy, fantastic job too. Plenty of questions coming in. And unfortunately, yes, that's all we have time for. I'm sure you found all the insight very useful, stimulating and certainly food for thought. You will all have access to the full audio replay and presentations within a week from now. So do share them with your colleagues, clients in the broader solar community. The aim of these discussions is to act as a catalyst for operational change in the solar industry. A big thank you again for tuning in and enjoy your weekend. Bye bye.