Installing Solar Electric Since 1983

 

History of Development of Wire management systems for Ground-Mounted PV

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Once module manufactures stopped providing junction boxes we had to develop procedures to protect PV wiring. This need is greatest with ground mounted PV systems. Ground mount racks are like jungle gyms to a child and the voltage present is absolutely fatal in potential. As of 2008, the National Electric Code mandates wire shield in "readily accessible" locations. Unfortunately, racking manufactures have been totally remiss by not providing wire managements systems. Therefore we have developed our own. Below is a brief progression of these systems.

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One of our first wire shields. The module connection points are oriented towards the center of the rack. The wiring is covered with a U-shaped aluminum channel. The channel is electrically bonded. The cost is about $150.00 per rack.
The Direct Power Top-of-Pole rack is ideally suited for wire shielding -- it has opposing aluminum channel that readily holds wire shielding materials. Here we have progressed to using #9-3/4 flat expanded aluminum.
Working with Direct Power, we developed a perforated sheet metal wire shied. This product was tedious to install and Direct Power never offered it to the industry.
Direct Power developed a ground-mount system utilizing a single line of poles (Multi-Pole Mount or MPM). This created more headaches for wire management because each column of two to four modules tilts independently. One shield can only protect one column of modules, not two.
The first step is to mount a PV cable transition box (see PV Cable wiring). This was accommodated by building some brackets from flat aluminum stock.
The second step is to secure the wiring in place so it can be captured under the shield. The P14 rail provided allowed slotted PVC to be slipped on to hold cabling in place. This turned out to be a bit of over-kill but it looks very neat.
Back view of the completed installation.
This is a top view of the completed system.
Next we developed a wire shielding system for Direct Power Large Ground Mount. Shown here is the racking before wire shielding.
We cut sections of #9-3/4 expanded aluminum and bent them in a brake.
We slipped sections of the bent material in between the flanges of opposing rows. All wire shields need to be bonded in case the material comes in contact with energized conductors. Here again the industry has let us down. We use dual-rated split bolts for bonding.
And here is the sunny side of the completed system.