Handling of strings in the module manufacturing with a Schmalz string gripper SSG

Vacuum Technology for Module Manufacturing

A photovoltaic module consists of multiple solar cells that are electrically connected to one another and permanently laminated by foils into glass. The manufacturing process is more and mored automated and is significantly characterised by the handling of glass. The module is assembled in layers with the active side or “sunny side” of the module on the bottom.

In the first process step, the EVA film is applied to the cleaned front glass. Then, strings are placed on the film. Afterwards, the individual strings are connected to one another and covered with another EVA film, as well as the back sheet or a second layer of glass. This unit is permanently bonded in a lamination process at a temperature of approx. 140°C while a vacuum is applied. After lamination, the edges are trimmed and the junctionbox is assembled. Finally, the module is framed, measured, classified by electrical output and packed.


Schmalz Inc.
5850 Oak Forest Drive
Raleigh NC 27616
United States of America

Tel. +1 919 713-0880
Fax +1 919 713-0883
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Requirements for Vacuum Technology

Short cycle times in stringing procsss
The cells are destacekd from the transport boxes and supplied to the stringing process with short cycle times. This requires both high acceleration rates and high positioning accuracy. The wafer gripper SWGm with optional integrated Bernoulli modules SBSm provides minimum gripping times and optimized cell separation. The double-layer sensor DLD detect on-the-fly whether one or multiple cells are grippers.

Gentle cell and string handling
When handling strings, it is most important to avoid damaging the cells at the edges of the busbars. Suction cups with a very soft sealing lip, such as the series SGPN, enable gentle handling. In addition, the ready-to-connect string gripper SSG was developed for handling entire strings. The gripper is equipped with suction cups and an ejector, and is available for both automated and manual handling.

High shear force on glass
Throughout the entire process chain, glass is handled dynamically with a wide variety of requirements. During loading of the line, the glass is often coated with separation powder. The suction plates SGF have a special structure on the suction area to absorb powerful shear forces even when working with suction plates coated with separation powder. In processes that require not only shear force, but also high flexibility and adaptability, the suction cups SAB with 1.5 folds are the optimum solution. Both suction cups are made of the markless material HT1.

Ergonomic handling – automated or manual
Throughout the process chain, glass and modules are handled automatically or manually. The modular suction spiders SSP offer a turnkey solution for automated handling, from destacking the glass plates to flashing and commissioning of the modules. In addition to automated solutions, manually operated tube lifters Jumbo can also be used. The tube lifter only uses vacuum to lift and lower the modules. This ensures minimal transport times and ergonomic handling.

Key Products for the Module Manufacturing Sector

Wafer Grippers SWGm

  • Dimensions: 125 x 125 mm and 156 x 156 mm
  • Selectable base model with axial exhaust air or sideways exhaust air
  • Material suction plate: PEEK
Suction Plates SGF

Suction Plates SGF

  • Diameter: 125 to 400 mm
  • Material: EPDM, HT1
Bellows Suction Cups SAB HT1 (1.5 Folds)

Bellows Suction Cups SAB HT1 (1.5 Folds)

  • Diameter: 22 to 125 mm
  • Material: HT1
  • Connection nipple vulcanized to elastomer part

String Gripper SSG

Suction cup: FG 19 HT1
For different lenghts, cell spacings and amounts of cells

Flat Suction Cups SGPN

  • Diameter: 15 to 40 mm
  • Material: FPM, HT1, NK, SI
  • Connection nipple plugged into elastomer part

Vacuum Suction Spider SSP

Custom made End-of-Arm-Toolings

Tube Lifter Jumbo

Ergonomically tube lifter
Lift capacity up to 300 kg
Pneumatic swiveling unit