With a recent drive in the industry to move towards more sustainable methods of energy and power generation such as solar, fasteners are often overlooked in the design process, despite playing a crucial role in connecting multiple components. Here, Star Fasteners outlines its range of Huck® fasteners specifically designed to withstand the harsh environments in solar applications and why architects and fastener suppliers should be ready with solutions now.
When developing solar arrays optimising the design of reliable solar racking and tracking structures for durability and reliability is paramount. Fasteners play a crucial part in the overall success of a project, frequently connecting multiple components to create a securely fastened joint which transmits both static loads – snow, as well as dynamic loads – wind. Wind and vortices that introduce energy to the solar array at just the right frequencies can create dynamic loads that quickly overwhelm the system, causing catastrophic failure.
The sub frame, racking or tracking assemblies are important components as they provided the core structure and strength and can be subjected to the highest stresses and strains. They must survive without compromise in performance, any effect on the structural integrity can mean many hours of lost energy production and costly repairs.
Often, the most vulnerable point on a design is where there is an interface or join between components. Nuts and bolts have over centuries been used in wide range of applications, both intricate assemblies through to mammoth installations. Bolted joints are designed to achieve a specific tension. The bolt acts as a spring to generate and retain preload in the joint. If the bolt is not stretched or elongated correctly by both the tool and the operator, targeted preload cannot be achieved and maintained. Even when installed and checked, the installed values of a nut and bolt can vary significantly. After installation often self-loosening takes place, this is when the threaded fastener loosens by rotation as a result of repeated slippage in the joint. Wedge washers and pre-applied high strength adhesive can often help, but these are an additional component and expense. Typically, a physical post-installation inspection is necessary to ensure that all bolts are tightened to specification, a visual check of a nut and bolt does not ensure it is correctly torqued. On a solar farm for example, there are likely to be thousands of fasteners, so additional checks post-installation would be costly and time-consuming.
To combat these issues, Star Fasteners UK Ltd, the largest UK distributor of the Huck® product range, offer alternative fastening solutions. HuckBolts, (also known as LockBolts), offer distinct advantages over traditional threaded fasteners for connecting permanent PV racking system joints.
Huck fasteners are precision engineered to deliver unmatched installation speed, fatigue life and vibration resistance, tested and proven in solar arrays around the world. Known for their industry-leading shear and tensile strength, once installed HuckBolts deliver consistent clamp. They have been designed to be tamper proof for an additional measure of security for valuable PV panels.
Consistent, high clamp force
Each HuckBolt performs identically in terms of strength and clamping force. Other mechanical fasteners such as nuts and bolts must be installed using torque, which varies with friction. HuckBolts also consist of two parts – a pin and a collar but use an entirely different installation method to nuts and bolts. HuckBolt’s clamping force is determined by the stretching of the hardened metal pin and the swaging of the collar into the pins locking grooves during installation.
This direct metal to metal contact of the collar swaged into the grooves of the pin eliminates the loosening effects of transverse vibration. Specially designed installation tooling (driven by pneumatic, pneudraulic or battery power) is used to install the fasteners. Measured clamp force holds the projects assembled parts together.
Recognising the cost associated with assembly time, HuckBolts installations are extremely fast; typically, just two seconds. The time saved by utilising HuckBolts is significant when considering the large number of potential fastening points. It could be argued that the cost of the HuckBolt fastener and installation tools are more than those of a nut and bolt, but when considered, the high fatigue strength of HuckBolts means that fewer are needed. Joint integrity is not compromised, and overheads are quickly saved in other areas. Post-installation, Huck® LockBolts only require quick visual inspection, saving even more time and cost.
Irrespective of whether threaded fasteners or HuckBolts are chosen, the most effective method to prevent self-loosening is to ensure that the mechanical properties of the joint are correctly determined and that there is sufficient clamp force present on the joint interface; it must be enough to resist the applied loading and prevent the joint from slipping. However, by installing HuckBolts, an engineer can count on many benefits including maintenance free joints; lower lifetime cost of joint; will not loosen even under extreme vibration; high speed, easy to install systems that can reduce production time by 75%; improvements to health and safety; as well as being tamper-proof.
Love or loath then, solar panels are definitely the way forward, whether that is in the form of huge solar farms, or as part of the architectural landscape. Where space is at a premium, placing solar panels on rooftops or more visible areas such as facades is going to be a necessity. Conventional ways of fitting and fastening solar panels will be challenged, buildings of the future will be at least in part, solar architecture buildings. The future strategy of solar is dynamic, and it’s a great time to explore how Huck® fastening technology can become a component of solar design of the future.www.starfasteners.co.uk
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