Confocal displacement sensors measure gaps in PV solar modules

To date, the production of photovoltaic (PV) modules has been a very complex, cost-intensive process. However, French company Apollon Solar has developed a new process for the production of PV modules. These systems are manufactured at French line constructor, Vincent Industrie.

The patented NICE (New Industrial Cell Encapsulation) process, the solar modules are no longer fused with a transparent plastic layer. By using the NICE process, the sealing and leak integrity of the module compound and the long-term stability are significantly improved compared with conventional PV modules.

During production of the NICE modules, a metal plate forms the rear side. The solar cells are arranged on this plate and electrically connected to each other. Next, spacers are applied as a cover, which prevents contact between the solar cells and the glass pane. A special-purpose system then presses the glass pane onto the PV module, evacuating it whilst doing so. After pressing, the PV module is permanently held together by the vacuum in the module and the external atmospheric pressure. The glass used is a special, anti-reflective type that allows light to pass through but prevents the light from reflecting.

Consistent spacing of the front and rear sides is critical during the pressing process. Sensors from Micro-Epsilon's confocalDT range of confocal chromatic displacement & thickness measurement systems are used here. Integrated in the press, these sensors measure the gap at several positions from one side, between the front and rear side of the PV modules. These gaps are between 0.7 and 2.0mm. Due to its very high light intensity, the confocalDT 2402 sensor is able to obtain sufficiently large reflections despite the anti-reflective coating on the glass. Using special, multi-peak software, the sensors are able to accurately measure the thickness of intermediate layers through glass, including the air gap between the two glass panes.

Distance and displacement measurements

The confocalDT series is a new generation of confocal chromatic measuring products from Micro-Epsilon. The system includes the fastest controller currently available in the world. The confocalDT produces highly accurate results for distance and displacement measurements, as well as for measuring the thickness of transparent objects. A large selection of sensors, interfaces, and simplified, web browser-based operation provide huge potential for applications in semiconductor manufacturing, solar panel and glass production, medical devices and plastics processing.

This measuring principle enables high-precision distance and displacement measurement, both for diffuse and reflecting surfaces. In addition, thickness measurements can be carried out for transparent measuring objects. The web browser interface provides an extensive materials database, which can be individually edited and extended. Up to six peaks can be evaluated to facilitate measuring multi-layer objects. The new controller offers an excellent signal/noise ratio for high-precision measurements. Rapid surface compensation helps to control illumination cycles for achieving high signal stability.

The confocalDT confocal measuring system consists of a controller and sensor, which are linked through a fibre optic cable. The controller has an internal LED light source which is capable of measurement speeds up to 10kHz. For faster measurements, an external Xenon light source is used. This is a separate, compact light source that sits alongside the controller, enabling measurement speeds up to 70kHz. The controller is easily configured via a web interface. The sensor range includes IFS 2400/2401 standard sensors, the IFS 2402 miniature sensors, and the IFS 2403 series of hybrid sensors.

Follow the link for more information about Micro-Epsilon's range of confocal displacement sensors.