PV Modules generally have a life span of 25 years and most of these have integrated wires connection between modules and from modules to combiner box to inverters. Cables are subjected to thermal, mechanical and external loads. Just like the rest of the system, cables need to last the stipulated 25 years or more. Being exposed to harsh environmental conditions like temperature fluctuations and direct UV can damage unprotected cables, and in turn the wires in them that carry the power generated. As a result, we need wire management solutions that can endure the extreme environments in which PV arrays are installed while ensuring the systems are safe and reliable. Now before we suggest the solution let us take a look at the some common problems in cable management.
Common wiring mistakes
Pinched wires: Pinched wiring problems are encountered in most of the PV installations. But this not so serious mistake may prove to be costly as the pinched wires tend to cause ground faults in the PV array. While installing PV the module output wire gets pinched between the module frame and the metal mounting system, giving the current an easy path to ground. Below shown are the figure showing pinched cables.
Fastening: Fastening may seem to be an easy process but it is the most important as the condition of cables depends on it.The fastening of cable through ties, clips and other attachment tools should be carried out such that the electrical properties of the cables are not compromised. Too much slack can cause cables to be accidentally yanked out or tripped over. If the cables have little or no slack, and are pulled relatively taut, then the tensile strength of the cable would be called into question. So the fastening process needs to be addressed with greater care. Moreover cheap cable ties that are not UV-rated can possibly fall apart after a few years. And they are not hardy enough to brave through 20 to 25 years of sun, rain and curious animals with a penchant for plastic. Metal wire ties, cut the wires and causes fault.
When too many cables are tied together with cable ties, overheating can happen, which in turn increases resistance and this causes power loss/cable losses.
Sharp edge: When cables are laid over sharp segments of the mounting racks for example, there is a possibility that movement over time can result in the outer jacket of the cable getting cut. Below shown is the cable cut due to sharp edge of the support structure.
Wiring Management – Using Cable trays
Although the initial cost of the cable tray may be higher than conduit, the labor time and cost of a cable tray installation can be much lower. That’s because working with conduit and pulling wires is extremely labor-intensive. Many types of cable trays are commercially available. The most commonly used is the “ladder” type, which provides excellent ventilation and drainage, and is affordable and easy to work with.Now a days snake cable trays are also widely used. Snake Trays are able to bend and flex in many different directions to accommodate the twists and turns your network cables need to take.
Advantages of cable tray over conduit
- Faster installation: Installing cable tray is far less labour-intensive than conduit, so you get the job done faster and get the plant back to production sooner.
- Easier maintenance: When properly installed, cable trays and cables are easier to inspect and cost less to maintain.
- Greater flexibility: Cable trays are more flexible as compared to conduit wiring system as they can be bend, cut easily.
- Improved Ventilation: With a cable tray due to the improved ventilation and it’s much easier to install multiple trays than multiple conduits.
- Compliance with standards: For global companies, one of the best ways to improve operational efficiency is to establish consistent methods across their facilities. Using cable trays in both new and expanded or reconfigured facilities provides a perfect opportunity for standardization