Thinner glass, larger formats and new materials bring reliability risks that standard IEC tests alone cannot capture.
Fraunhofer CSP called for statistical glass strength testing, as IEC load tests use only one or two modules.
JA Solar and DMEGC Solar use butyl rubber edge sealing to gain active cell area and block moisture.
Trina Solar's quarter-cut Vertex N G3 runs up to 50°C cooler at hot spots under shading, per its simulations.
TÜV Rheinland's extended testing revealed wide quality differences among modules that are all certified.
Munich Re insures module warranties only after factory audits, UVID testing and cell inspection.
PV module design never stands still. To raise efficiency and power while using less material and cutting costs, manufacturers are following different routes. At the same time, PV manufacturers are adopting new cell and module technologies. These efforts are leading to thinner glass, new encapsulation and interconnection schemes, new cell architectures, and leaner bills of materials. Each step can make modules more competitive, but it raises corresponding reliability questions that earlier designs did not. Modules are also becoming application-specific, with optimized bills of materials (BOM) to be suitable for a wider range of scenarios and climates. One design no longer fits every site, making product-specific design, testing, and qualification more important than ever.
This was the focus of the TaiyangNews Reliable PV Module Design Conference, held online on October 15, 2026. The speakers at the conference represented different parts of the value chain, including research institute Fraunhofer CSP, module manufacturers JA Solar, Trina Solar and DMEGC Solar, testing and certification body TÜV Rheinland, and reinsurer Munich Re. The conference concluded with a panel discussion titled Higher Efficiencies, Lasting Performance.
A solar module is expected to work outdoors for 30 years, through heat, humidity, UV, wind, snow and hail, and manufacturers back that with long warranties. Opening the conference, Shravan Chunduri, Head of Technology at TaiyangNews, said even a household appliance is judged by how long it lasts, yet the solar industry offers warranties of up to 30 years almost without question. The topic needs fresh discussion every year because change moves so fast: new cell technologies, larger formats, and new materials keep arriving, and each brings risks that past field experience does not cover. Solar may be the cheapest source of power, but that holds only if modules deliver the energy they promise over their full lifetime.
Ralph Gottschalg, Head of Fraunhofer CSP, opened the technical sessions with the growing problem of glass breakage. He cited the 2024 IEA PVPS findings that some systems show 8 to 10% glass fracture, and said claims are rising. Modules have grown from about 1.7 m² with 3.2 mm glass to 2.4 to 2.8 m² with glass as thin as 1.6 to 2.0 mm, often alongside new mounting structures. Changing several parameters at once, without studying how they interact, changes how modules behave mechanically. The glass industry treats fracture strength statistically because not every pane breaks at the same stress. IEC mechanical load tests, by contrast, usually use just one or two modules, and glass standards do not properly cover thicknesses below 3 mm. Fraunhofer CSP tested 19 specimens of 2 mm glass in four-point bending and estimated the 5% quantile strength at 114.6 MPa, with a 95% confidence interval of 101to 130 MPa. Such strength distributions could support batch acceptance testing. Finding the root cause of a breakage is hard: debris may break a pane that was already weakened during manufacturing. Gottschalg said manufacturers, owners and installers often run separate, costly investigations while the same failures repeat elsewhere. He urged the industry to "stop blaming" and share findings, test under field-relevant loads, tighten production quality checks, and give clearer datasheet information on mounting, mechanical limits and maintenance.
JA Solar's Product Manager, Djamel Eddine Mansour, explained how multi-cut cells and gapless interconnection have driven new design measures, including a patented buffer layer to prevent microcracks. The company's high-insulation edge sealing uses butyl rubber, which cuts the creepage distance between live parts and the glass edge from the usual 10.4 mm to around 3.5 mm. That frees roughly 1% more active cell area. Butyl is non-polar, has a very low water vapour transmission rate and is chemically compatible with the encapsulant; the design is qualified to standard and already in production. To tackle glass breakage, JA Solar uses a staggered, triangular arrangement of mounting holes, which passed mechanical load testing and was checked for compatibility with structure and tracker suppliers. Under five partial-shading scenarios, the new design performed one class better than a half-cut alternative, with low losses even under diagonal shading. Caption: JA compares conventional and triangular mounting-hole layouts to demonstrate improvements in mechanical stability.
Ling Zhuang, Product Manager at Trina Solar, presented the Vertex N G3. Its quarter-cut cell design uses four parallel substrings per branch, against two in conventional half-cut modules, combined with a triple-segment junction box. Trina's simulations show about 20% more power retained under shading and maximum hot-spot temperatures 50°C lower than conventional modules. Trina uses finite element analysis to study static loads, vibration and fatigue, and has strengthened the aluminium frame. In a one-year outdoor study in Zhangbei, the modules stayed intact with stable output despite strong winds. Changes to the anti-reflective coating and encapsulants limit ion migration and moisture ingress, earning the module TÜV Rheinland's Anti-PID PV Module AQM Award 2026. Incoming material checks, supplier audits, process monitoring and pre-shipment testing keep batches consis
René Schüler, Head of Product Marketing Europe at DMEGC Solar, said the Infinity RT 3.0 utility module has moved from 630 W to 645 W through changes to cell layout, materials and design, with 660 W planned. Its HDS+ (High Density Secure Plus) technology also uses butyl rubber edge sealing in dual-glass modules, adding active area while improving moisture protection and insulation. After 3,000 hours of damp heat, HDS+ modules lost under 3% power, against over 5% for conventional modules in DMEGC's comparison. A 0.5 mm cell overlap further reduces inactive gaps. DMEGC also offers application-specific products: an anti-glare module measuring 14,000 cd/m² at a 10° incidence angle versus 100,000 cd/m² for a standard module; HW4 and HW5 hail-resistant designs with 3.2 mm and 4.0 mm front glass; and the 15.6 kg IFM 2.0 compact module for small rooftops and repowering, which raised capacity in a sample roof layout from 5.7 kWp to 8.4 kWp.
Max Köntopp of TÜV Rheinland said IEC 61215 and IEC 61730 are designed to catch early design failures, not to prove performance over a full warranty. TÜV's extended bankability testing goes further, with independent sample selection, factory audits and batch testing within the supply chain. The test sequence covers LID, PID, extended UVID and energy yield, and passed modules are ranked by performance, with a lead time of about six months at any TÜV lab. Results show wide variation even among certified products: thermal cycling and damp heat results differed sharply, pointing to differences in metallization quality, and UVID results also varied significantly. Sequential mechanical stress tests produced many of the weakest results. Köntopp listed current supply-chain risks as mechanical stability of larger modules with thinner glass, hail, TOPCon metastability, UVID and PID, while noting that new cell technologies themselves show no major issues.
Ronald Sastrawan of Munich Re, one of the world's largest reinsurers, explained how it insures module warranties. If a supplier can no longer honour excessive warranty claims, for example after insolvency, the project owner is indemnified. This cover must be requested during procurement. Before insuring, Munich Re runs its own due diligence: a technology assessment, reliability testing that now includes UVID, mandatory cell-level inspection and scored factory inspections. Each factory receives a non-conformity report, and corrective actions must be completed before cover is granted. Munich Re also models the distribution of annual degradation rates from its own measurements.
Panel: Higher Efficiencies, Lasting Performance
The closing panel focused on testing gaps and the challenge of ensuring 30-year performance. Gottschalg said IEC qualification tests mainly catch early failures and cannot reliably predict 30-year behaviour. Sastrawan backed more demanding UV testing, particularly for TOPCon modules. The panel noted that standards often evolve only after new failure mechanisms appear, and called for testing based on specific failure mechanisms, materials and climates rather than simply longer test durations. Schüler stressed extended testing while keeping development timelines practical. Köntopp called for closer cooperation between module, mounting-system and inverter makers to avoid compatibility failures, and said insurance requirements raise minimum quality but may not push makers beyond it. Sastrawan pointed out that a 30-year warranty is only as good as the manufacturer's financial stability, while Gottschalg asked for better reporting of field failures back to manufacturers.
The conference made one message clear – certification and insurance alone cannot guarantee that a module lasts 30 years. Manufacturers are answering new risks with design changes such as butyl edge sealing and stronger frames, but speakers agreed that testing must become more statistical, more field-relevant and more open about failures.