This article is for those just starting out in the photovoltaic market, but it may surprise experienced installers. The traditional hammer head screw has been replaced by several manufacturers of fastening solutions.
A known disadvantage of the hammer head screw is that, in some cases, when the rail groove is not perfectly adjusted, the screw head may rotate during the assembly process, which does not provide a good fixation.
One of the solutions proposed on the market is the use of a cylindrical head Allen screw, associated with a rectangular clamp with a threaded hole, acting as an inverted nut. The aforementioned inversion refers to the position of the nut. While in the hammer screw solution the nut is mounted on top, in the cylindrical screw solution the element that acts as the nut is mounted on the bottom, inside the groove.
Aluminum profile
Each fixing solution requires a specially designed aluminum profile. An example is the anodized aluminum profile produced by BelEnergy, illustrated in the figure below. The roof supports are fixed through the side channel of the profile, while the clamps are fixed in the upper channel.
Fixing elements
In the figure below we see the difference between this fixing solution, which consists of a set of cylindrical head screws and threaded holes. The cylindrical allen screw head provides ease of handling and good torque capacity.
Meanwhile, the threaded hole clip fits perfectly into the rail groove, allowing smooth assembly without the risk of rotation of the fastening element inside the groove. In the figure below you can see how the clip is positioned inside the groove of the aluminum profile.
In the figure below you can see how the clip is positioned inside the groove of the aluminum profile.
The screws are supplied together with the fixing parts (clamps, supports, etc.). To fix these screws, the installer must use a 6 mm Allen key. A manual wrench can be used or you can use a screwdriver, as shown in the images below.
In the BelEnergy solution, which we consulted to prepare this article, for example, the screws are measured M8X25 and M8x45. The smaller screw (M8X25) is used with the roof supports and end clamps. The larger screw (M8X45) is used to fix the intermediate clamp to the profile.
In the BelEnergy solution, which we consulted to prepare this article, for example, the screws are measured M8X25 and M8x45. The smaller screw (M8X25) is used together with the roof supports and end clamps. The larger screw (M8X45) is used to fix the intermediate clamp to the profile.
“L-foot” support with solar rod
Figure 5: L-shaped foot with shank
This support is used for fixing on the tile. Typically, in fiber cement tiles. However, it can be a solution for cement tiles too.
Answers of 3
I really liked this content.
Good morning,
This system is good for the assembly operation, providing perfect fit of the tightening tool.
The only problem I see when using this type of screw is the accumulation of dirt inside the hexagon, which over time can accelerate oxidation, especially if the screw is made with low-chromium alloy stainless steel.
If the structure suffers wind load, the screw may break.
Low chromium stainless steel alloy is not completely immune to oxidation.
I do not classify this problem as having a high degree of criticality, especially if the design and assembly are well done, the need for future maintenance will be very low.
Good product