ACI-ecotec has developed an automatic contacting system, the ecoContact, which requires less than 40s to manufacture a thin-film PV (photovoltaic) module completely. The system offers high speed and high contact quality. This flexible, advanced system can be used to apply small pieces of adhesive tape for attaching bus bars. The system thus helps to save the cost spent on adhesive materials.
The fully automatic contacting system comprises standard components for applying conductive adhesives, longitudinal and lateral contacting and soldering bus bars, in accordance with the corresponding production technology. These components can be combined in a flexible way to manufacture all common thin-film module sizes. The substrates are transported and precisely positioned using a multi-lane conveyor belt.
The conductive adhesive is applied via two dispensing heads at speeds of between 40 and 70mm/s with ongoing monitoring of the needles. Any bumps or irregularities on the surface of the glass plate are automatically levelled out. Due to the controlled, high-precision application, around one gram of adhesive is required for a substrate that is 1300 to 1400mm long. The position, length and distance between the adhesive strips can be programmed flexibly because the CNC heads operate autonomously. This enables the application of more than two adhesive strips without modifications.
Following the application of the conductive adhesive, the substrate is automatically indexed and aligned for longitudinal contacting. The tin-plated bus bar is applied using reels. The bus bar holds up to 380mm of material and minimises downtime due to changeovers. To maintain the required tension between the continuously spinning reel and cyclical application of the bus bar, the system has an integrated bobbin. The bobbin detects if the bus bar left on the reel is insufficient and stops the machine automatically, thereby minimising substrate waste. To prevent the bus bar from breaking loose until the adhesive has cured at over 100°C in the laminator, the bus bar is fixed with specially designed adhesive tape. In conventional contacting, this tape is applied along the entire length of the bus bar. The company has deployed a solution that automatically cuts small pieces of tape from the roll, removes them from their backing and sticks them onto the bus bar at predefined points. This economic use of the adhesive tape enables significant increase in system availability. The same solution is used for lateral contacting. At a different workstation, the bus bar contacts are soldered together and their ends are turned upwards or downwards in accordance with the customer's specifications. Optionally, the glass cover can also be applied fully automatically.
Like the adhesive dispensing station, the standard components for longitudinal and lateral contacting are fitted with two autonomous CNC units for attaching the bus bar. The solution has programmable axes and allows production to continue while maintenance work is being performed on one of the dispensing heads or application components. Each ecoContact module is based on a stable steel structure with an integrated switchgear cabinet. The design saves space and enables rapid implementation of the contacting system.