PV "Hinge" Wiring Technique |
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Click any photograph for a high res image. |
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There is a common problem encountered when connecting the wiring between modern solar electric (aka Photovoltaic or PV) panels: The wiring is under the panels and once the panels are in place it is difficult to get to the wiring in order to make connections and to secure the excess wire in place. |
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Most solar installers do not take the time to attend to the important detail of managing wiring. After the panels are in place the installers reach under the panels to plug the connectors together and haphazardly tie the wires up with nylon cable ties. The problem with nylon cables ties is that they do not stand up to the intense thermal cycling that occurs under solar panels. The temperature underneath solar panels can range from extremely hot to extremely cold on a daily basis. This causes the ties to become brittle and break. The wiring can droop onto the abrasive roof surface and high voltage conductors can become exposed. The voltage in the wiring of most residential solar arrays can reach up to 600 volts, DC or 240 volts AC. This voltage can be fatal. Imagine a child losing a frisbee or ball under your solar panels and trying to retrieve the toy with a scrap metal pipe found in the garage. If the wiring is not secured it can abrade against the roof or mounting rails and insulation can be exposed or if the wires are snagged the metallic pins can become exposed. This high voltage can travel down the metal pipe and electrocute your child. See photograph below of a typical installation done without proper wire management. |
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Wires held in place by unreliable nylon cable ties |
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To allow for proper, well supported wiring under PV Panels, |
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Basically this means connecting wires while a panel is held vertical above the mounting rails in such a manner that the wiring runs past a point where the panel is resting on the mounting rails. When the wiring is complete the panels is pivoted down to a flat position as if it was hinged at the low side. This allows the wires to be supported for all but a few inches. This means the wires will remain supported in place during and after the lowering process. |
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| The photograph below shows a PV panel ready to be lowered to the rail for permanent mounting. The leads are clamped to the frame of the solar panel by stainless steel clips. After routing away from the panel frame the leads are routed inside of the mounting rail and held by clip(s) until they exit for a short distance to connect to the electronic unit found under almost every solar panels installed these days. | |
Panel ready to be lowered |
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| The panel will be lowered as if hinged on the bottom edge. The slack has been arranged so that the wires will not be pinched when the panel is flat on the mounting rail. | |
| This advanced wire management process is only possible if the solar panels come with leads that are of adequate length. There has been a disturbing trend in the industry to manufacture solar panels with short leads or leads that are connected to the panels in locations that render the leads too short to reach a hinge point. See this article for more information about this trend. | |
| Another requirement to make this wire management possible is to have mounting rail that has a channel wide enough to accept the PV cables. Below is a photograph of one of the more popular mounting rails branded Iron Ridge. This rail has no channel to accept and secure cabling. Iron Ridge provides clips to drape cables on but unless a clip is placed every 2 to 4 inches, the cables will droop between clips. We know installers are not installing this many clips. | |
Iron Ridge Mounting Rail |
Iron Ridge Cable Clips |
Before you hire a solar contractor ask them this questions: "What will you do to ensure the high voltage wiring under my solar panels is kept safe and secure?" |
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