pv magazine: The recent PI Berlin study illustrated how harsh climactic conditions impact on PV project quality in India. Is it that components used elsewhere, such as temperate climates in parts of Europe, are simply not up the challenge that the Indian climate presents?
Asier Ukar: Yes, but I want the context to be well understood from a broad point of view since the question must be answered from several angles.
First of all, we must take into account that in India we have four or five predominant types of climates, unlike other PV active areas such as the Atacama Desert (Chile), MENA or the Southeast Asian region – which have a much more homogeneous climate distribution. It is important to note that some of these climates, such as those in Chennai or Jodhpur, are especially aggressive. Considering that the IEC is not capable of guaranteeing a durability of 25-30 years in temperate climates, with less reason it is for India due to its particularly aggressive climate affecting almost all the components of a PV plant.
This is a great challenge when establishing standards at both macro-scale (BSI) and microscale, for example in specific tenders, since a module installed in Kerala will face a combination of environmental stressing factors different from the one for example in the Kutch desert in Gujarat.
pv magazine Quality Roundtable
But it wasn’t only the climate that impacted quality. Some of the faults found in your examinations are experienced, unfortunately, in many parts of the world. Is that right?
Exactly. Apart from the climatic heterogeneity and the aggressiveness of these climates, we are faced with a second problem that is more related to the quality of the modules. In these cases, the modules have systemic failures that make them fail regardless of the climate in which they are installed. We speak for example of detachment of the junction box or soldering failures. Obviously, the more aggressive the operating conditions, the greater the probability that the module will fail in a short period of time.
Does this then lend weight to the case that India needs its own quality standards in solar, such as from the Bureau of Indian Standards?
Yes, same as other markets with aggressive climates that require an additional effort to keep the plants operating with a high Performance Ratio and thus be able to take full advantage of the solar resource that their countries offer. The problems facing India, are not unique to India, we have found similar situations in other markets both in terms of the effects of climate on the durability of the components, and the low quality of the components installed, Europe is not spared from this either.
In this sense, I want to highlight the great work that the National Institute of Solar Energy (NISE) is doing in the fields of R & D, testing and certification, which is definitely pushing in the right direction.
What is it about some of the climate in India that causes problems. Is it primarily the combination of high UV and temperatures – as some component suppliers point to this particular combination as presenting challenges?
In India, there are at least seven PV relevant environmental stressing factors: salinity, humidity, high temperatures, high levels of UV radiation, abrasion, thermal stress and dynamic forces caused by wind. What makes India unique in a certain way is that in some areas of the country there can be up to six factors simultaneously; for example in some areas of Rajasthan or the Kutch desert in Gujarat.
From our experience in the field, one of the worst combinations that can occur in a plant from the point of view of safety and operability, is the combination of firstly humidity, then temperature and salinity. These factors, acting alone or together, can cause corrosion in grounding rods, corrosion in cells and MC-4 connectors, or insulation losses in cables and a consequent disconnection of the inverters and output loss.
A race-to-the-bottom in tender pricing appears, at least to me as an outsider, to be common in India. But we have also seen cost reductions being achieved by PV manufacturers, while maintaining appropriate levels of quality. What measures can manufacturers take to avoid things like delamination or failures at solder points?
Avoiding delamination or inadequate soldering of the cells to the connectors depends on a delicate balance. For example, in the case of delamination, it is important to control the pressure and temperature in the lamination process, adjust the curing time appropriately, use glass without impurities and avoid folds in the EVA. When soldering the connectors to the cells, it is important to avoid a thermal shock between the cell and the electrode and to avoid excessive pressure on the cell that can cause micro-cracks.
Our experience as auditors clearly shows that while there are module manufacturers who are really committed to the quality of their products by applying even stricter measures than the norm demands, not all manufacturers of PV modules will apply all the necessary quality control measures voluntarily unless there is external pressure that forces them to do so. Some of these measures may be a strict RFP with clear pass / fail criteria specified in a tender, in an EPC contract or in a module supply agreement. In this context, the work of the TA is important in preventing manufacturing defects for example in the framework of a factory audit or production supervision. Once the problems appear in the plant, it is very difficult to eliminate them both from a technical and commercial point of view.
We often see handling problems as the root cause for quality problems down the road. How evident was this in the projects that you inspected?
We detected cracks and micro-cracks in PV modules in the six plants we inspected. These cracks showed clear patterns linked to bad handling and inappropriate transport. Walking, stepping or hopping on the modules automatically damages the cell structure and reduces the efficiency of the modules. This is a world-wide problem that affects most of the markets we have been involved in. Imagine this: a coin falling from two meters in height and impacting the rear side of a PV module will generate a crack which is detectable with electroluminescense. The module will be damaged at this particular location for its entire lifetime and no product warranty will cover this damage.
How do you think this can be avoided in the future? I mean, EPCs and installation crews are often under pretty intense deadlines.
With proper training of the EPC and the subcontracting companies prior to the start of the construction phase handling damage can be avoided. With five or six clear indications, more than 80% of the module damages can be avoided.
Introducing penalties for module damage is complex, since a large scale onsite electroluminescense inspection would be required, which is labour intensive and expensive. Treating the modules with care is not something that should be imposed, it should rather be part of the working methodology of each involved worker onsite. Once the plant has been commissioned, the O&M workers should be trained, too.
How important do you feel it is for the Indian solar industry to engage in a conversation about delivering quality components and installation in 2018?
It's a crucial condition for India to become the leading PV market in the world not only in terms of the capacity of installed GW, but in terms of reputation and prestige. Today, quality will determine whether an asset will reach the expected IRR or not. There is no buffer anymore, no feed-in tariffs, no subsidies as we had years ago, in short: there is no room for unexpected performance drops.
India has everything to succeed: willingness, a strong industry and natural resources. It´s only about redefining the bankability standards and get rid of the idea that quality control is expensive. This is my key message.
So, this is clearly important work that PI Berlin is doing in bringing these issues to light?
I believe it is, but NISE is carrying out vitally important that should be acknowledged also. I’d also like to thank PTB for contracting us in the frame of their project “Strengthening Quality Infrastructure for the Solar Industry in India” for conducting this study and acknowledge the efforts of MNRE, SECI, NISE and KfW in making the study possible.
Hear PI Berlin’s Asier Ukar deliver the findings of the study and engage in a discussion about two of the project’s inspected at the pv magazine Quality Roundtable at the Renewable Energy India conference on September 18.
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