How suitable are glass backsheet modules for FPV installations? If components of a project are damaged – either due the environment in which they are located, because of low-quality materials, or incorrect installation practices – can they be replaced? Or does the developer need to start the project from the beginning?
These questions and more arose during this year’s pv magazine Focus sessions – a series of quality-focused panels and presentations held as part of The smarter E Europe in Munich last week.
As part of the event, pv magazine’s Editor at Large Jonathan Gifford presented a case study of a 10 MW FPV project in Southeast Asia where things have gone badly wrong, almost from the outset. The project was unnamed but pictures shared anonymously with pv magazine were shown to the audience.
The images showed burnt-out cables, broken module glass, and faulty connectors. There were myriad problems, and as Gifford pointed out, many of the faults appeared just a few months after the project was commissioned in June 2023. An initial inspection carried out in September 2023 revealed severe faults. Third-party component experts were called in November 2023, and they discovered more faults.
Images from the project showed cabling partially submerged in water, adhesive residue on modules right across the array, connector mismatches, UV damage to cables, and poor attempts to repair damaged cables.
It was clear those involved were in over their heads. But the event was not about naming and shaming; the project remains anonymous for a reason. The images highlighted potential problems in the sector and ways the industry can avoid such mistakes in the future.
As most speakers who joined to discuss the case study agreed, quality standards for FPV projects are particularly tricky. There needs to be an industry-wide effort to address this.
Modules and glass
Dr. Fangdan Jiang, director of solar R&D at Chinese PV manufacturer Tongwei, said he believes that the industry needs to update some of its technologies and quality control processes around n-type, specifically, as it has a much more complex manufacturing process than its p-type and passivated emitter and rear cell (PERC) counterparts.
It is important for quality issues to be caught and addressed at the cell stage, before they are assembled into modules and put into PV plants, he added.
UV exposure and sunlight damage was one of the issues identified in the Southeast Asia case study. Jiang said that his company, Tongwei, is currently collaborating with others such as Canadian Solar and Jinko Solar, to propose a UV testing vessel for cells (rather than modules). UV radiation causes failures of encapsulation material and other components of modules.
“It’s very important to pre-detect the quality risk,” he said, explaining why Tongwei is focusing on the cell stage instead of the module level. The company is also involved in some fishery PV projects, but they are on freshwater, unlike the Southeast Asian case study, which is in saltwater. In addition, they are not typically mounted on floating structures, making conditions different. For its freshwater projects, Tongwei is using bifacial glass-glass modules. The Southeast Asia installation, on the other hand, features less-durable glass-backsheet modules.
Cabling and other challenges
Panelist Jan Mastny agreed with Jiang’s case-by-case approach, adding that the industry has to understand that FPV environments are very different from other, standard solar projects.
“I know that there are many initiatives relating to adopting the standards for the best practice guidelines for floating PV. Not all of them are ready for publishing yet,” said Mastny, who has years of experience as an independent solar consultant.
Caution is extra-important at the development stage of projects because the industry has, in many cases, advanced to become “way more dynamic” than some of the current guidelines allow for, said Mastny. “That's making it even more important that the development stage of the project will be very cautious and go way above what the guidelines and requirements ask us to do.”
Mastny’s area of expertise is cabling. He said that the case study should not have used aluminum cables, as they are not appropriate for FPV. “We need to take into account, not only the moisture or excessive moisture, but also the dynamic load and the structure. Not only the cable but many other materials need to be adjusted or adapted to the situation.”
The standards problem goes beyond cabling to all components of a project. The industry needs to realize that existing standards are not a “proof-of-concept” or proof of quality for projects. “The standard is not an indication of the quality, this is where the quality actually stops,” added Mastny.
“The standard is the minimum consensus among all manufacturers,” according to Dominic Buergi, head of services renewable energies at Swiss-headquartered supplier Stäubli Electrical Connectors.
Knowledge transfer
Buergi’s specialism is connectors, and like his fellow panelists he offered his verdict on the case study. In his view, the best way for the sector to overcome such incidents is to invest in the “knowledge transfer.” He pointed out that Stäubli provides training programs for installers and other stakeholders, so they can understand the consequences of mismatched connectors and how to avoid them.
Mastny agreed with Buergi that more training around standards will be needed to avoid catastrophes like the one that happened in Southeast Asia. He frequently encounters what he termed “very creative” ways of interpreting quality requirements. Gesturing to his fellow panelists, he said that he is sure none have seen many improvements regarding best practice, despite the fact that PV projects have been installed for more than 20 years at a commercial scale. The case study project is the tip of the iceberg.
“These kinds of very basic fundamental problems are happening again and again. People tend not to learn from the mistakes of others,” said Mastny.
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