Wires are good for two things: 1) Installing a kick-ass PV system 2) Tripping people up. To accomplish the first, you must avoid the second at all costs, which means implementing a sound wire management plan on projects of all sizes.
Just like the rest of the system, planning is important for both saving time and money. Tom Marsden and Vince Giglio from Heyco recommend laying out the cable routing on paper first before installing the solar cables. This will help you decide the best way to route the cables and what will be the most efficient use of cable mounting hardware.
Part of planning is of course purchasing, and knowing the most efficient ways to use what you’ve got.
“One way of saving time on installs would be to use stainless steel clips at the module level because you can install multiple clips in the same amount of time you can install a single zip tie, thus saving on labor costs,” says Vincent Marino, product manager for Nine Fasteners. “Also, when using micoinverters or optimizers connected to the panels, they can be applied prior to bringing the panel onto the roof.”
Oh, and one trend to note while planning — pest management systems are starting to be required in rooftop installations, according to Marsden.
In a ground-mount, Roger Jette, president of Snake Tray, recommends keeping your power cables above ground when possible to remove the need to trench or thread cables through pipe.
“Besides being labor intensive, there is a potential of derating the current capacity of the cable,” Jette says. “With voltages now approaching 2,000 V, there is a high potential for problems if not enough attention is spent on the proper cable conveyance. Without a good cable conveyance plan, there is a potential for degradation of the cable insulation leading to arc failure.”
We’ve heard plenty of horror stories from installers and manufacturers in regard to incorrect installation approaches or accidental errors, but the anecdotes that stand out most are those caused by wire management. Just seems silly to risk the performance of a $13,000 system by skimping out and choosing ties known to fail or clips known to dig into wires and cut them over time — the solar equivalent of losing a football game because of a missed extra point.
“Too many installers are sacrificing quality for costs. We have seen a number of installations
where UV nylon cable ties are breaking, only to be replaced with more UV nylon cable ties,” Marsden says. “This scenario is no different than buying something for your home. Are you going to buy an appliance that needs to be replaced every two to three years or are you willing to spend a little more up front, knowing your product is backed by a warranty?” He points to stainless steel cable ties as a less risky solution.
Your other purchasing decisions dictate what wiring will need to be done as well, especially with those installing rail-less systems. The lack of a rail changes your wire management options.
“As a New Jersey installer, many jurisdictions require wiring inspections to verify that rails have been properly grounded,” says Chris Torre, installation manager at Green Sun Energy Systems, which has been using Quick Mount PV’s rail-free system, Quick Rack. “We’ve been able to eliminate the cost of the second truck roll to the site, saving an average of $300 to $400 per project. The system has integrated grounding pins located on the panel clamps, so the system can’t be grounded until the panels are installed. With this system, we’ve been able to install as many as 68 panels in a single day with a three-man crew.”
Chris Crowell is the managing editor of Solar Builder.
— Solar Builder magazine