Video: Quality Roundtable tackles glass-glass issue and underground cabling

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In an industry that moves as quickly as solar PV, there is always the potential for issues with quality to creep in and threaten the success of a project, whether at the materials and component manufacturing stage or in the installation and operation of a PV power plant.

To tackle quality issues before they occur, and to ensure that solutions are available, there’s a need for frank discussion of problems that have been discovered, and an industry-wide approach to developing standards and solutions. pv magazine’s Quality Roundtable returned to The smarter E Europe show this year to highlight cases of substandard quality seen in the field, and to offer solutions to some of the major issues causing worry among PV stakeholders today.

The first case study, presented by CEA’s Anika Giller, concerned the complexities of filing a warranty claim with a manufacturer when a quality issue is spotted. “Filing a warranty claim is not a smooth process,” stated Giller. “It takes sensitivity to negotiate, to speak to final decision makers.”

The discussion revealed further complexities, with participants noting that problems can be caused during transport and installation, as well as on the production line, and can even start further upstream. “Root cause analysis is extremely complicated,” noted Rene Moermann of solar quality control company Xilia. “In this case for example, poor soldering could be caused by poor materials rather than poor soldering quality.”

 

Glass-glass

Next, the discussion moved on to glass-glass modules — an important issue thanks partly to the rapid growth in bifacial that the industry is currently undergoing. Lucie Garraeu-iles, technical manager EMEA at DuPont, noted several studies that demonstrate a range of issues with glass-glass modules, including higher breakage rates during transport and installation, as well as due to movement and bending once deployed in the field, and increased balance-of-systems costs. “Glass is brittle, and it breaks,” Garraeu-iles noted. “That’s a potential inherent weakness.”

This topic was discussed further by an expert panel, which concluded that while more performance data is needed, the case for glass-glass production is strong as long as standards are maintained. “Both technologies [glass-glass and glass-backsheet] can be very good, there is enough data to show this,” stated Jörg Althaus, regional field manager at TÜV Rheinland. “It’s a matter of the right materials and processes.”

This panel discussion also brought the need for accurate testing solutions to the fore, with participants referencing historic issues with polyamide backsheets, which have exhibited high failure rates in the field, despite meeting standards laid out by the IEC. “Testing is the key to building confidence in the solution,” noted Garreau-iles. “PA backside was tested to three times the IEC — it just means three times as wrong. You have to test it in a test that is relevant to panels in the field.”

Going underground

Further case studies presented at this year’s Quality Roundtable showed how issues with faulty or underperforming cabling can lead to underground cabling having to be rewired, and even whole projects needing replacement components, at huge expense to the project owners.

The importance of cables, connectors and other small components to a PV plant’s performance, however, is still often underestimated by installers and project developers.

A panel discussion on this topic focused on the best practice for burying the cabling in a PV installation, finding that plastic conduits used to house cabling underground will never be able to keep moisture out for an entire project lifetime, meaning that ingress protection is needed for all underground cabling. While this can come in the form of a cable with an internal metallic layer, this raises another set of safety and cost issues.

The discussion concludes that, similar to glass-glass and other areas, real testing that simulates field conditions, and the sharing of information gained from this will be the most effective way to ensure quality in any PV project. “A test submerging a cable in water for two weeks is nothing,” commented Faruk Yeginsoy, head of operations, business unit solar and windpower at Leoni. “We are talking about systems in operation for more than 20 years.”