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Solar lamination

During the solar panel production process, one step is the lamination of the solar modules. Solar modules are typically composed from a number of wafer-based solar cells or a single thin film sheet. They must be protected from ambient influences (weather, scratching, etc.) to ensure long lifespans.

This protection is created by assembling the cells inside a sandwich, consisting of a top layer of glass and a hard back layer. A polymer is used to “glue” the sandwich together, which is done under heat, vacuum and mechanical pressure. Vacuum is required during this process step to degas the plastic resin in the modules in order to avoid bubbles.

The most commonly used polymers are EVA (Ethylene-Vinyl-Acetate), POE (Poly-Octene-Ethylene) and PVB (Poly-Vinyl-Butyral). All these polymers show some degassing during the heating process, which then enter the vacuum pump. Historically, oil-sealed pumps have been used in this application, but they require intensive maintenance, as the oil is contaminated by the outgassing. Due to high operational costs, oil-sealed pumps today have been largely replaced by dry screw pumps.

Since the released hydrocarbon vapors are quite reactive, they also present a challenge for dry compression pumps. Entering the pump, these vapors tend to build layers wherever the inner pump's body temperature is excessively high. Leybold’s dry running and oil-free SCREWLINE SP 630 excels in this process, as the pump temperature is kept low through an internal rotor cooling mechanism. Unlike most of the competition’s hotter pumps, the SP 630 temperature remains low, so there’s hardly any build-up of layers The SCREWLINE can operate in this demanding application for many years without special maintenance or service, while hot-running pumps get stuck after a short time.

These days, two- or three-stage laminators have become very common. Here, the process is split into “Lamination” in stage one, “Solidification” in stage two and “Cooling” in stage three. In stage one, the SCREWLINE SP 630 is a must, as here, the majority of the polymer outgassing is removed. For stage two, the more energy-efficient DRYVAC is an excellent alternative to the SP630. The stage three cooling chamber requires rough vacuum only, and is less demanding. Such chambers are typically pumped by a claw-pump, such as our CLAWVAC.

In large laminators, the SCREWLINE is often combined with Leybold's Roots-pump WSU 2001 (or similar). This can be added on top of the dry pumps in order to achieve higher suction speeds.