During the development of a production line for thin-film photovoltaic tubes, Afag has substantiated its assembly process expertise and equipped essential machine stations with specifically configured handling systems. Under the project management of tubesolar and Eichstätter Maschinenbau, a system for an innovative and future-oriented product has been developed at tubesolar in Augsburg that combines area protection with energy generation and is unique worldwide. The system concept allows the PV tubes to be automated using dynamic, high-precision handling components and manufactured through purposeful deployment of all the various resources.
Economic, social and political spheres are grappling with solutions to securely meet future industrial, public and private energy needs. High electricity prices, climate crisis, sustainability, renewable energy – the areas of activity are as pressing as they are complex and they need new ideas. The general trend towards electrification has significantly exacerbated the problem of how primary power is to be most efficiently generated. At the same time, the protection of resources and land area and the ideal use of such are also vitally important issues. The fledgling company tubesolar manufactures a product that brings together environmental protection and energy generation on the basis of high-end technology: Thin-film photovoltaic tubes that are assembled into create modules to protect the ground from intense solar radiation or hail – for example, for use in agriculture, public areas and in modern building technology – and simultaneously generate electricity.
tubesolar has been using the patented technology to manufacture tubes since 2019. Based on know-how pertaining to the manufacture and processing of glass tubing gained by former lighting manufacturer Osram, the technology combines this knowledge with the latest photovoltaic (PV) developments. The photo-electric effect in a thin-film layer of semi-conductors enclosed within an encapsulated glass tube generates electricity. tubesolar joins 40 PV tubes together to create a system module with sufficient gaps left between the tubes to allow light and water through. This results in weather-resistant and simultaneously wind, light and water permeable solar modules that combine a protection function with electricity generation.
A globally unique system – there is no prototype
Tube manufacture to date has been in the form of a semi-automatic pilot production with low output performance. In late summer 2020, the decision was made to develop a fully automatic production facility with high output performance. The specialized plant engineers Eichstätter Maschinenbau won the tender to construct a production line on the basis of a tubesolar concept for the production plant in Augsburg.
“This system for manufacturing thin-film tubes is unique worldwide and extremely complex because, in addition to glass melting, it encompasses vacuum, rinsing, and heating processes as well as various inspection stations with cameras and a plethora of servo motors,” explained Dominik Bauernfeind, project manager at Eichstätter Maschinenbau. The task required both profound design know-how and pertinent experience in assembly automation. Eichstätter Maschinenbau promptly brought in Afag as a cooperation partner. “As the leading provider of assembly automation, Afag certainly demonstrated its high level of process expertise in the implementation of this system,” emphasized Dominik Bauernfeind. “We were already in close contact from other projects. Afag quickly and fundamentally grasped what detailed solutions were required for the processes at each station. Important selection criteria for us as plant engineers were primarily the cycle time, reliability and precision, which made Afag the first port of call.”
Two design specialists get on with the job
In a joint design effort, the engineers from Afag and Eichstätter Maschinenbau assembled the melting and pump machines, where glass tube melting and vacuum pumping takes place within the system. The starting product is a glass tube already equipped with a loose, inlying PV film. This tube is manually placed onto the line and initially heated. At the same time, to seal off the tubes on both sides an Afag handling system transversely separates the glass frames that are pre-arranged in rows. Here at the start of the process, equipped with Afag modules for gripping, rotating and transversely moving, the handling system has to feed and handle an extremely high volume – essentially two frames per tube. The required cycle time is ultimately achieved thanks to the exceptional dynamics of the handling modules.
Next up after the thermal glass melting process and matching the frames to the tubes is the quality control. Via an Afag pick and place station featuring linear modules and swivel units, the tubes are then further conveyed along the line to a buffer station. The next step, also using a pick and place unit, feeds the tubes to the pump for evacuation. A thermal process laminates the PV film to the inside of the tubes, which are then filled with gas. Afag modules also have an essential function at the melt off station. A linear module on the pump slide pulls the exhaust tubulation away from the glass so that the end is cleanly sheared off and sealed following melt off. An Afag pick and place unit again ensures onward conveyance.
Durable premium modules for superlative dynamics and precision
Exceptional dynamics, process reliability, meticulous part handling and high-precision processes – these exacting requirements were stipulated by the system designers for the handling and assembly components. Afag respectively configured specific handling systems with their proven red modules for each of the processing stations. Specifically installed in the facility are compact and flexible type PDL30 and PDL40 portal axes that provide maximum travel in the smallest of installation spaces. The miniature PG20 and PG16 pneumatic precision grippers impress with their highly precise jaw guidance. Also compact are the CR20 and CR25 rotation modules, yet they still deliver high mass moments of inertia. Sophisticated and precise gripping and rotational tasks are carried out by the slimline, pneumatic DG20 gripping rotation module, which can be installed vertically or horizontally. An impressive feature of all the Afag modules is their performance, robustness and durability. They reliably carry out their work even after millions of load cycles. Users consequently benefit from a high degree of availability, fewer system outages, low maintenance costs and a consistently high productivity level.
“We are extremely proud to have been given the opportunity to apply our assembly and handling expertise in this project,” said Dominic Nägele, Head of Engineering Services Afag Solutions: “Thanks to the excellent cooperation with Eichstätter Maschinenbau, notum engineering and tubesolar, an efficient system for a clean and future-oriented product has been installed that has massive potential to succeed in numerous areas.”
Below shade, above electricity generation
The PV modules combine a protective function with electricity generation. This enables new projects to be realized in which it is no longer necessary to choose between a PV facility or an alternative use of the land. Dual use of the same land makes both options possible. Thanks to the cylindrical PV tubes, users can consistently generate electricity all day long. A roof greening function is also maintained. Electricity can be directly generated above the green area. Consistent shading benefits the many areas of application: Cultivated fields in the agricultural sector, for example, but also carports, pergolas, communal areas, patios, pools and energy-independent housing.
Contact for further questions:
Marketing & Communications Manager Afag Group
M.: +49 151 11129543