TNO develops module with rear contact solar panels

Together with partners, TNO is developing a module based on heterojunction solar cells in which the contact points are placed at the back. This increases efficiency. The modules must be able to be produced on a large scale.

TNO is developing the modules under the project name Whooper, in collaboration with Eurotron and Groenleven, who are respectively responsible for equipment for the production of rear-contact solar panels and the installation of a test set-up. With Whooper modules, TNO places the contact points largely at the back of the solar cells. According to the institute, the advantage of not having to solder the cells is that the electrical resistance in the module is reduced. In addition, TNO points out the advantages that the front of the panel is more aesthetically pleasing and that less silver needs to be used.

As both the cell and module architectures are already being used individually, TNO expects the integration to be suitable for large-scale production. The institute claims a four percent increase in efficiency and lower costs compared to conventional heterojunction silicon solar panels. The parties will install the modules at a test location in Emmen in order to obtain more details about the yields. In addition, they will examine how robust the modules are and further investigate the feasibility of large-scale production.

Heterojunction solar cells are developed by Panasonic and are characterized by high efficiency. The cells consist of three different photovoltaic layers. Between the top layer and the bottom layer of amorphous thin-film silicon is a monocrystalline silicon. TNO uses these cells to combine them in modules with its own, patented method with Metal Wrap Through. This would allow the institute to achieve an efficiency of 23 percent.

From left to right: TNO’s Whooper module, placement of cells on foil and cell structure in detail