Strong-Ty™ Cable Ties: Long-term UV Exposure made possible by Kynar® PVDF
Current PV installations have a 25-year life expectancy. However, the nylon and polyethylene cable ties can fail in a matter of months due to UV exposure and temperature extremes. The possibility of failure makes a system-wide inspection of cable ties a constant requirement in order to prevent ground fault failures. Fortunately, there is a better choice for long-term PV cable ties
The use of Strong-Ty™ cable ties made from Kynar® PVDF is a better choice for PV wire and cable management. Accelerated UV exposure under a Xenon arc for 5000 hours in addition to five years of Florida sun exposure shows no change in mechanical or chemical properties in several varieties of the Kynar® copolymers. This data was recently presented by Arkema at the 2017 National Renewable Energy Laboratory (NREL) PV Reliability Workshop. A portion of the presentation is available below.
Based on the simple calculations, UV radiation should not provide sufficient energy to break the chemical bonds found in most commodity plastics such as polyethylene and nylon. However, embrittlement and loss of tensile strength occurs in these materials and is thought to be the result of chemical impurities or structural defects. These irregularities along the polymer chain absorb energy and initiate polymer degradation. Kynar® PVDF shows no effect or change after long-term UV exposure.
An example of Kynar® PVDF performance under constant UV exposure is a PVDF coating system for metal roofs called Kynar® 500. One coating applicator, Metal Sales, offers a 25-year warranty against colour fade and chalking and a 45-year warranty against blistering, cracking and peeling. This same company only provides a 25-year warranty on the steel substrate against rupture, perforation or structural failure. More confidence in plastic than steel