By Doris Schulz

Going by the number of orders and requests received by the company PV Products GmbH (PVP) based in the Styrian town of Wies in Austria, it was clearly the right decision to produce not only conventional glass-film photovoltaic modules but also to invest in manufacturing equipment for producing high-quality glass-glass solar modules. Standard high-efficiency modules are made from 156 x 156 mm mono- and polycrystalline silicon cells in three product series with 48, 60 or 72 cells. The company, which was founded in 2009, is also flexible about supplying solar modules in special dimensions, various formats and different colors. Thus, PVP manufactures glass-glass modules in any size up to 3500 x 2100 mm using either Laminated Safety Gass (LSG) or LSG-insulating glass. Furthermore, round and triangular formats can also be produced. The glass solar elements are laminated with PVP film which is available in a wide range of colors. This enables individual color requirements to be met.

High Demands Placed on the Production Line

In order to be able to implement such a high level of flexibility cost-effectively, PVP needed a partially-automated production line which fitted the company’s requirements exactly. It also had to be possible to convert the line rapidly in order to produce different-sized modules. “We spoke to a number of plant manufacturers and finally opted to work together with ACI-ecotec. The decision to collaborate with the company from the Black Forest was partly based on the company’s excellent consulting service and partly on the concept of its manufacturing system S30M. The human factor also played an important role and enabled us to work together in a highly-constructive manner”, stated Karl Kurbisch, one of the managing directors of PVP.

In its present state, the S30M production line can manufacture solar modules with a capacity of 30 MW/a fully-automatically. It also possesses manufacturing units which enable 5 MW to be produced. The integration of a second stringer as well as additional robots for cross-contacting has already been taken into account in the plant design, thus enabling production capacity to be increased to around 60 MW/a.

Combined Line and Customized Production

The first station in the manufacturing system is the glass-cleaning unit which is fitted with a crane. On completion of the automatic cleaning and drying processes, the first encapsulation film is applied manually. Special formats are then diverted to flexible manufacturing units while standard glass panels continue on to the lay-up station. At the same time, solar cells are singularized in the stringer, checked by a camera system, positioned correctly and busbars applied and soldered. Depending on the module, two or three busbars are applied. A clamping system holds the busbars accurately in position until they are soldered. This ensures accurate lines and a flawless appearance even in the case of extremely long strings.

A handling system positions the completed strings so that they can be picked up by a robot. Before placing the strings on the glass panels, the robot first passes them through a testing unit to control the solders. The busbars are then shortened automatically to the correct length. A particular feature of the lay-up station is a special drawer system. “It enables us to produce strings in advance during work-free time at weekends and store them there. In this way, we can optimize line capacity,” explained Karl Kurbisch.

Cross-contacting takes place in the next step. Two robots are needed to do this. The first robot lays copper strips onto the panels and the second robot holds the strips in place with a clamping unit until they are soldered. “ACI-ecotec recommended that we use an inductive process which gives us top-quality connections. It also has the advantage that neither solder nor flux are required which could impair the quality or service life of the modules,” said the managing director.

Modules processed at the flexible workplaces are returned to the main production line before application of the second encapsulation film and covering film or second glass panel, respectively. 

Three-Step Laminating Process

The laminator was also specially constructed for PVP’s S30M production line and is designed for a three-step process. “The first step is pre-lamination in a membrane press. A second lamination layer is, then, applied using a conventional press and the modules finally subjected to a cooling process. The solution enables us to carry out processes parallel to lamination, resulting in a significant increase in capacity,” explained Karl Kurbisch. In order to use the capacity of the laminator to a maximum, PVP combines several modules each time to form a batch.

Insulating tape is, then, applied to the sides of conventional glass-film solar modules, the modules are framed fully-automatically and the aluminum frames crimped. Finally, a junction box is glued on and encapsulated.

Module Efficiency Up to 295 W

For the purposes of performance checks and quality control, all solar modules pass through a flasher optimized for use in serial production. The design of the flasher not only enables modules to be checked at high speed, but the components used in its construction also ensure a long service life, high availability and minimum maintenance requirements.

For example, the monocrystalline, 60-cell modules from PVP have a capacity of up to 250 W and the 72-cell version has a solar yield of up to 295 Ws.

Environmentally Friendly, Even during Production

The Styrian company not only practices environmental friendliness with its products but also with its production methods. Pumps and heating for the laminator are located in a separate technology room. This reduces noise and heat levels in the production hall and thus ensures pleasant working conditions. PVP also uses wood chips for heating the halls and, as from this fall, for the heating unit of the laminator, too.

Doris Schulz has studied Business Administration at the “Fachhochschule fur Wirtschaft,   Gestaltung und Technik”, Pforzheim, Germany and worked with different companies in public relations.