Selecting the Correct Engineered Plastic
Commodity plastics are appropriate for general-purpose applications but in solar or other outdoor applications, the short-term value can quickly lead to uncontrolled maintenance costs. Simple UV-rated and PA66 outdoor grade materials can deliver in certain situations but fail to measure up to environmental extremes. An engineered plastic makes it less likely to slice through a cable jacket.
Climate and site conditions need to be carefully considered to determine what products make the most sense for a given application. Some solar materials are formulated with UV stabilizers, UV absorbers or exceptionally strong base plastics designed for extended lifespans. Depending on your application, we offer budget-friendly solutions that outlast so-called value-priced products – all the way up to our new 25-year PVDF products for the most maintenance-free cable management you can get.
Material Comparison
DigiKey Products
PA66 Products
PA612 (PA6/12) Products
Nylon 12 (PA12)
PVDF Rated Cable Tie (High UV)
All PVDF Fluoropolymer-Based Product
Temperatures and Heat
Rooftop solar installations can often reach 160-180 degrees F (70 to 82 degrees C) and utility-scale solar farms are often installed in some of the hottest regions of the world. When talking about solar systems and wire management, temperature is one of the most common reasons plastic components fail. Most cable ties from the big box stores are rated for a maximum of 150 degrees F. While the price may be “right,” these ties become brittle and begin to break down in a matter of months, not the years a PV system is rated for.
The graphs below reveal how temperature impacts fastener strength. The data on the left shows strength over time at 30 degrees C; the graph on the right that shows how much faster plastic materials degrade at high temperatures. Heat stabilizers and heat stabilized materials are critical when specifying long-lasting wire management products.
Moisture Resistance
Moisture Resistance We normally don’t think of plastics absorbing water. Nylons (PA66/polyamides) are hygroscopic materials, meaning they absorb and release moisture. Water content in polyamides is important during the manufacturing process. It’s also important for the molded part’s physical properties, as the mechanical properties of a polyamide material are affected by its water content – especially flexibility and minimum tensile strength. HellermannTyton’s proprietary blend, PA66HIRHSUV, stands up better to moisture fluctuations, because the impact modifier prevents brittleness, even in the driest of conditions. Nylon 12, POM and PVDF are non-hygroscopic and are much less affected, if at all, by moisture.
Chemical Resistance
Many chemicals can come into contact with a PV array, including sprays for dust and vegetation suppression, pest control and other various elements. Plastic wire management eliminates the chance of dissimilar metals reacting with one another through galvanic corrosion from salts and moisture.
UV Exposure
UV exposure can be an issue even on the back of a panel. Between 20 and 30 percent of the sun’s energy can hit the back of the panel due to the reflectance – measured in albedos - of the soil. Our solar materials are formulated with UV stabilizers, UV absorbers or exceptionally strong base plastics designed for extended lifespans.
Plastic-Coated Metals
On paper, a metal wire management component coated in plastic or rubber is the best of both worlds – the durability of metal with the insulating properties of plastic. Our experience shows the coatings adhere poorly to stainless steel and they break off after only a few years of environmental exposure. Another consideration relating to longer term O&M costs is detection. If a plastic wire management component fails, the failure is obvious. If the coating on a metal part fails, it may be impossible to see damage to conductors. This can lead to arc issues that may cost much more than the replacement costs of failed wire management.
Summary
All wire management systems are subject to improper installation. It is imperative to understand the installation crew’s capabilities and the care they will give to the smallest details of securing wire safely. Or, chose a fastener that is tolerant of a wide variety of installation methods. In choosing a particular material or type of wire management component, metal tends to be more forgiving to install but less forgiving to the cable if installed improperly. Plastic wire management runs the opposite, requiring more care to install but ultimately gentler on cable insulation.
DigiKey Products
PA66 Products
PA612 (PA6/12) Products
Nylon 12 (PA12)
PVDF Rated Cable Tie (High UV)
All PVDF Fluoropolymer-Based Product
Applicable Terms
PA66HIRHSUV
As a base material, PA66 is a
weak UV resistant material.
HellermannTyton’s unique blend
includes added UV stabilizers,
impact modifiers and heat
stabilizers. This material offers
excellent cost savings while
withstanding the everyday
wear and tear in most solar
applications. PA612
PA612 is a copolymer blend
optimized for tensile strength and
performance comparable to PA66
in environments with humidity
cycling. PA612 also provides good
resistance to chemicals, oils and
salts, while providing effective UV
resistance. The material has higher
tensile strength and provides more
flexibility in manufacturing than
PA12. Nylon 12
This material absorbs
little moisture, making it
a consistent performer in
environments with humidity
cycling. Basic PA12 provides
strong resistance to chemicals,
oils and salts, while providing
excellent UV resistance. PVDF
Our fluoropolymer-based
material provides some of
the highest UV, chemical and
thermal resistance of any
plastic resin. Extraordinarily
long lasting, PVDF can virtually
eliminate wire-management
failure over the life of a PV
system. Tensile strength vs. temperature
and moisture content for
DuPont Zytel® 101 – general
purpose Nylon 66 resin.