Though wire management is often overlooked, it’s an important part of PV array installation and longevity. Proper wire management minimizes maintenance, optimizes safety and enables longer-lasting systems.
“Wiring has no standard warranties and is likely the first component of the system to have problems or fail completely. When this happens, it’s generally the solar provider’s responsibility to fix the issue,” said Andrew Wickham, marketing manager at SnapNrack. “Poor wire management could lead to service calls every couple of years, each costing hundreds of dollars.”
There are many potential issues that could arise when wires and cables aren’t secured. These components are subject to extreme temperatures and often direct sunlight, wind, snow and rain. Sharp panel and mounting system edges can score cables, and rough roof shingles can abrade insulation with continual rubbing. Rodents and other animals enjoy living under the shade of solar panels and munching on dangling wires. Such damage not only jeopardizes the system’s reliability, but also its safety.
“One underrated conversation when discussing PV system safety is wire management,” said Sarah Parsons, Wiley product manager at Burndy. “Proper wire management is vital to the health of the PV system. Damaged wire insulation can lead to ground faults, system downtime and fire.”
But these problems can be nearly eliminated with proper wire management.
What is wire management?
Wire management involves properly routing, supporting and protecting PV system wires and cables.
The only current wire management standard for the solar industry is NEC 110.12 (mechanical execution of work), which states, “Electrical equipment shall be installed in a neat and workmanlike manner.”
“This is very subjective and does not hold installers accountable to any specific work requirements,” Parsons said. “With no real industry standard for wire management, it’s difficult to police subpar installation practices and products.”
Still, wire management is about being neat and using common sense, such as ensuring wires are tucked away so rodents and other creatures don’t have access. Wires should be run in a manner that avoids damage to their insulation and conductor, avoiding sharp edges, rough surfaces, moving parts of racking systems, direct sunlight and overly tight bends.
“PV wires are not unbreakable and do have limitations when it comes to elasticity,” Parsons said. “Not observing the specified bending radius of cables can cause internal damage to the fragile copper/aluminum strands within. Not securing the wires in proper intervals puts excessive stress on connection points, the junction box and connectors, as seen in NEC 690.31 C2. Additionally, over-tightening cable ties puts pressure on wires, cutting their protective insulation.”
Wire organization and identification is another important aspect of wire management. Using wires with colored insulation is required by the NEC and helps identify circuit conductors.
“Properly organizing wiring refers to grouping, routing and labeling wires in a manner that can make for easy identification of different circuits for future maintenance and emergency personnel,” said Stuart Fox, VP of technical sales at CivicSolar, in a blog post. “Labeling strings and DC and AC circuits within junction boxes is another good practice allowing for better troubleshooting by future maintenance personnel.”
Wire management products
Proper wire support means securing wiring along PV modules and racking equipment, or in conduit trays. Accomplishing this task requires choosing appropriate components like stainless-steel wire clips, UV-stabilized composite wire clips and UV-stabilized wire ties.
Stainless steel wire clips are available in many forms to meet a variety of needs. Fox said that these clips are designed to fasten to module frames or mounting rails. They can clamp single or multiple PV wire(s), or USE-2 or TC-ER cables. Some manufacturers provide 90? clips when the clipped surface length is perpendicular to the cable route.
UV-stabilized composite cable clips, from inverter and racking companies such as Enphase, IronRidge, Unirac and SnapNrack, also attach to the mounting rail and support a variety of wire types and quantities.
When clips and cable ties are not able to provide sufficient support, Fox recommends using conduit and cable trays. Also, array-edge screens like those from SolaTrim and SnapNrack protect wiring from animals.
Using appropriately sized and listed solutions is also crucial to system longevity. Using generically-rated materials that are not UV or corrosion-resistant can lead to breakdown. Products should be listed as required by NEC 690.31 and to UL standards.
SnapNrack’s Wickham sees an industry-need for an integrated wire-management solutions.
“By integrating wire management into the solar racking system, not only are wires and cables protected from damage throughout the life of the system, but the system owner is pleased by the finished aesthetics,” he said.
The SnapNrack Series 100 and Ultra Rail pitched-roof systems provide two separate channels large enough to neatly route PV conductor wires and AC trunk lines. Junction boxes snap into rail channels without additional roof penetrations to conceal and protect electrical connections.
Utility-scale solar wire management
Utility-scale solar projects require extra consideration when it comes to wire management.
“With utility-scale projects, there is more wire, there are often more elements and, with a tracker, there is obviously a lot more movement,” said Nick Korth, product marketing manager at HellermannTyton. “With all that movement, special care must be taken to make sure the wires are safe from harm.”
To account for movement, understanding thermocycling is critical.
“Early in the morning in some parts of the country, the temperature can easily be 50? to 60? cooler than at midday,” Korth said. “The structure can move, and so too will the clips or ties. The result can range from a brittle cable tie breaking because it is not suitable for outdoor environments, to cable damage and a fault due to sharp edges on a cheap metal clip, to connectors slowly separating because they are held in place too tightly.”
Utility projects also operate at much higher voltages than residential installations.
“Today’s solar arrays are operating at voltages in excess of 1,500 V and amperages greater than 500 A,” said Roger Jette, president and founder of Snake Tray, a cable management manufacturer. “Therefore, an individual who is walking around on wet grass in a field of thousands of rails can be at risk. Installers must adhere to NEC safety procedures in such environments.”
While trenching is still an effective method for creating a physical barrier from electrical charges, Jette is seeing more systems built with increasingly sophisticated cable management. For example, his company’s Solar Snake Max cable containment system allows for code-compliant cable separation without trenching. Instead, it mounts to vertical pilings or poles.
Proper installation is critical when it come to the effectiveness of wire management systems.
“All wire management systems are subject to improper installation,” Korth said. “It is imperative to understand the installation crew’s capabilities and the care they will give to the smallest details of securing wire safely.”
When choosing a particular material or type of wire management component, Korth said that 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,” he said. “Careful consideration needs to be taken when choosing plastic or metal materials.” HellermannTyton has published a white paper with more information on pros and cons of metal and plastic wire-management components.
Korth also sees wire-management standardization advancing.
“The more standardized the industry gets when it comes to these large systems, the more costs can be driven out and the fewer parts needed on the spec,” he said. “We can then standardize how wires are being routed and protected. Until then, wire management strategies will continue to change platform to platform.”