This is the first in a series explaining common mistakes and animal guard failure modes.
In the photo below, wire mesh wraps around the outside corner of a solar array. At the corner, the mesh has been partially cut through, leaving a large gap for animals to pass through. Unfortunately, this is a common mistake. How did it happen?
The answer has to do with the J-hooks that attach the wire mesh to the solar panels. For J-hooks to hold wire mesh in place, the mesh MUST splay out from the array and be supported by the roof, as illustrated below.
This outward splay is necessary because unlike SnapNrack or CritterBlok, J-hooks do not fully support the mesh. If the wire mesh were suspended above the roof, there would be nothing to stop it from getting pushed under the array by animals, snow or wind.
Because of this splay, a slit must be cut into the mesh when wrapping it around a corner.
Most J-hook manufacturers recommend patching each corner using an extra piece of wire mesh and zip ties. Unfortunately, these patches are ugly, unreliable and time consuming to install. Unscrupulous installers will not bother with the patch, as we saw above. Even if a patch is applied, it will only last as long as the fasteners holding it in place (about 2-5 years for plastic zip ties in our experience).
Here are several ways to avoid all of these problems:
Solution 1: Don’t use J-hooks
Whenever possible, we recommend the Rail Mount Method or a full-support clip like CritterBlok instead of J-hooks. Those methods allow wire mesh to wrap cleanly and continuously around corners with no splay.
Solution 2: Use wire mesh C-channels with J-hooks
Sometimes you are stuck with J-hooks – for example, when installing animal guard to a railless PV system. In these situations, use wire mesh C-channels instead of the traditional L channel. In addition to getting clean, patch-free corners, your entire pest barrier will be more durable.
Just like the Rail Mount Method, the wire mesh is bent into C-channels on the ground and tucked into place between the roof and the PV array. However, attachment is done with J-hooks instead of self-tapping screws. At each J-hook location, cut a small tab in the upper flange of the C-channel, so that the tab presses against the outside edge of the PV module. This keeps the wire mesh from being pushed under the array. Below are some examples of the finished product.
Solution 3: Secure patches with metal hardware
If you absolutely need to patch a corner, do not use plastic zip ties. Instead, use hog rings which are faster to install and will last for decades. Check out our AG Sourcing Guide for more info on hog rings and stainless zip ties, which are another good option.
We hope this info saves you and your team time and money! Share with your coworkers using the links below, and join our email list to get notified as we continue this series.