Light gets supported by Structural Bonding
Which possibilities photovoltaics open up? The sector is nowadays facing a rough head wind with the current economic situation and the volatile governmental incentive schemes. Probably the biggest challenge in this situation for the module producers and integrators is cost reduction, combined with a continued improvement in the quality of the module and system, particularly with regard to longevity and performance. An additional subject is the need for diversification from competition.
The structural bonding technology allows tackling these challenging requirements by reduced material consumption and labor, increased productivity, less stress on the modules and new design options. The adhesive and bonding technology is not as young and unknown as many would think. It actually exists since several thousand years and presents in many industries an indispensable technology.
30 kg of adhesives in one car
Like the automotive industry, where an average car includes nowadays about 30kg of adhesives and it proved to be a major factor for the significant cost reductions and safety increase. Many other industries can be outlined which went for this advantages as well; like facade, rail, marine or wind industry. With these proven advantages in hand and the potential values for the photovoltaic module production and installation, this technology should definitely catch attention in the solar and photovoltaic industry.
All existing solutions should be challenged for improvements
As cost reductions over the whole system from module to final installation are required, all existing solutions should be challenged for improvements. One of the things which could be questioned at first is the need for the aluminum framing and later clamping of the crystalline PV modules.
The aluminum frame consisting of eight pieces in total and requires sophisticated assembly equipment in high volume production and counts for about 5-7% of the material costs per module. Thanks to the proven structural bonding technology, simplified and frameless mounting systems become feasible and already exist, which ensure a lifetime of over 25 years.
15% total cost reduce
With such systems the overall costs could be reduced by up to 15%. In the PV thin-film sector this technology is already state-of-the-art. The reduction of the metal content of the system has an additional advantage in the positive effect in CO²- and eco-balances.
No risk of stress peaks
The advantage of the structural yet flexible adhesive technology is that the loads of wind, snow or dead load are distributed over the module area. The risk of stress peaks or module bending, as it may occur on framed or clamped modules, is minimized due to the elasticity of the adhesive. Therefore the risk for glass breakage or micro-cracks in the PV cells is negligible.
Furthermore due to the smooth surface, compared to the overlapping edges of framed modules, dirt, snow or leaves are washed off more easily, which reduces the maintenance efforts. Both of these advantages have a positive effect on the long term yield.
Structural bonding technology increases the architectural appeal
Additionally larger module dimensions becoming more easily feasible without a large impact on the general system, respectively the system can be rather easy adjusted to the dimension. Another aspect is the electrical grounding which is required with framed photovoltaic modules.
As with the frameless modules, installed through a bonded mounting system, there is no contact to life parts, no grounding is needed. For building integrated photovoltaic (BIPV) the structural bonding technology increases the architectural appeal thanks to hidden constructions and new design options. The PV modules can be completely integrated into facade systems. This opens and increases a new application field for the industry.
Reduced installation time by as much as 40%
The highest spectrum of the benefits can be achieved by using the solution within the module production line. By the frameless design the sophisticated frame pressing and sealing can be abandoned. With the new adhesive technology it is possible to bond and assemble the back rails or other mounting devices to the modules within standard production cycle times and the handling is feasible directly or short after.
As the back rails are already part of the mounting system, the modules can be directly fit or hooked into the prepared substructure, without the need of time consuming screwing or clamping. Existing solutions have proven that the installation time can be reduced by as much as 40%.
Lifetime of more than 25 years
As the photovoltaic systems have a high life time expectancy of 25 years or more, combined with the demand for low maintenance and high processability, the right selection and application of the adhesive technology as well as quality control is crucial. It should not be neglected that the systems can be installed in different climatic zones with UV radiation, loads from wind and snow as well as temperature changes.
The test for structural bonding of the EOTA ETAG 002 (European Organization of Technical Approvals), provides a common standard from the facade industry for structural glazing, proves itself as the preferred test method for the structural adhesives. This standard is accomplished with the assumption that the positively tested material will withstand a life time of more than 25 years.
High process and material savings
Innovative photovoltaic module manufacturers and integrators will go for the structural bonding technology to benefit from the process and material savings. It not only shows cost saving potentials but a chance for forward integration in direction to end customers or differentiation from competition. As existing examples in the solar and many well established industries proved, the structural bonding technology is a valuable solution.