The invisible tape

Paul Boughton
Christina Barg-Becker reports on an adhesive innovation for fixing cells within crystalline solar modules.

The per capita consumption of energy is increasing steadily throughout the world. In order to satisfy this demand for future generations, more and more importance is being attached to the use of renewable energy sources. It therefore comes as no surprise that those sectors involved in the generation and storage of alternative energy have experienced rapid growth in recent years. However, providing technologies that use nature as a sustainable energy source is in itself no longer sufficient. Modern bonding techniques are therefore moving ever further to the fore, with innovative adhesive solutions playing a crucial role.

The more reliably and efficiently components are connected, the more long-lasting and cost-effective the technical solution will be, irrespective of whether this is for energy production from solar systems, wind turbines and fuel cells or for storing energy using modern battery technologies.

For many years, Lohmann has been developing bespoke products in conjunction with mechanical solutions for the renewable energy sector.

These include mounting tapes for bonding thin-layer solar modules to "back rails" (reinforcement profiles made of steel or aluminium), which are affixed in pairs to the rear of the frameless solar modules. The modules are then joined to a collector structure via the 'back rail bonding'.[Page Break]

Large-scale solar modules with a typical area of between 1.4 and 5.7 square metres can be effectively installed in this way. This design also ensures stable adhesion, even in the face of extreme weather conditions, such as storms, ice or snow.

As in the majority of industrial sectors, the manufacture of thin-layer solar modules is a highly automated process in which reducing cycle times is playing an increasingly important role.

Put into context, this means that the availability of materials from the supply chain - such as the appropriate adhesive tape - and its application are both critical for the successful realisation of this trend.

Further applications include fixing tapes and insulating adhesive tapes for busbars and thin-layer modules, adhesive solutions for use in the production of wind turbines or pressure-sensitive tapes for framing photovoltaic modules, to name just a few.[Page Break]

The invisible tape

Against this backdrop, the 'bonding engineers' in the building and renewable energies market segment have developed and patented a remarkable product for fixing cells within crystalline solar modules. The product is a single-sided adhesive laminating tape comprising an Ethylene-Vinyl-Acetate (EVA) - compatible carrier material together with a mesh-like coating of special adhesive. This adhesive tape represents a completely new way of securing solar cells and has many advantages for the user. For example, it has a sufficiently high initial tack with respect to the EVA material and the rear of the cell. This enables the 'strings', a collection of solar cells connected in series within a module, to be held in place during the lamination process.

As the carrier material and the multi-layer films in the solar modules are made from EVA, the adhesive tape is rigid and resistant to deformation prior to lamination. This prevents the cells from 'drifting" and facilitates both manual and automatic application. Another factor that makes this DuploCOLL adhesive tape unique is its tremendous adaptability. Owing to its compatibility with all other components, it remains invisible following lamination - no inclusions or discolouration. The adhesive tape can be supplied as a directly applicable die-cut for ease of use.

Enter √

Christina Barg-Becker is with Lohmann GmbH & Co KG, Neuwied, Germany.

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