STABILITY OF BLACK INTERCONNECT COATINGS FOR SOLAR PHOTOVOL-TAIC MODULE APPLICATIONS

Aesthetics is crucial in the development of Building Integrated Photovoltaic (BIPV) products. Manufacturers strive to mask, typically through expensive manual processes, the reflective metallic interconnects to obtain uniform module colors. Inks offer an automated alternative but must be implemented in the production line and remain stable, maintaining their appearance over time. In this study, three black metallic ribbons were tested: one commercially pre-coated and two coated with UV-curable inkjet printing. Accelerated UV-light exposure was applied according to IEC standards on coupons mimicking glass/backsheet (G/Bs) samples including encapsulant with and without UV blockers. Additionally, one-cell modules with ink-coated ribbons were fabricated using a laboratory-designed automatic inkjet printer and exposed to accelerated UV ageing. Results showed that the commercially available coated ribbon remained stable after 120 kWh/m² of UV exposure. However, UV-curable inkjet inks caused color changes in the encapsulant around metallic interconnects, regardless of the encapsulant used or the presence or not of UV blockers in the encapsulant. Ink #1 exhibited the most color change under UV-dose. Its main component, 2-phenoexyethyl-acrylate (2-PEA), photodegraded and caused yellowing. An early sign of degradation with a slight increase of 22% in carbonyl index (CI) was observed after 15 kWh/m² of UV exposure. Encapsulants with UV blockers successfully mitigated 2-PEA photodegradation on G/BS laminates; however, color change occurred with ink #1 despite their application. Using this ink on PV modules results in color change, but the electrical performance remains relatively stable, with less than a 3% power loss after 360 kWh/m² of UV exposure.