Laser Modified Glass for High-Performance Photovoltaic Module

Abstract

The solar module output power is the power generated by all individual cells in their specific electrical circuit configuration, multiplied by the cell-to-module power ratio. The cell-to-module power ratio thus reflects the sum of the losses and gains produced by the structure of the module. The biggest process change in module design during the last few years was the introduction of half cells. Another important trend is the use of bifacial cells to build bifacial modules. These two trends increase parts of the module that correspond to the intercell gaps, and the light does not meet the cell in its path. This part of the radiation is therefore not used efficiently. Scientific efforts focus on the texturing surface of covering glass and cells, and the introduction of narrower ribbons and encapsulation materials with improved UV performance, etc. The concept of a diffusor that actively redirects light from the intercell space into the cell was proposed in the past, in the form of a micro-structured prismatic film, but this is not applicable for bifacial modules. The conclusion is that losses caused by the incidence of light on the areas of the photovoltaic panel not covered with solar cells yet are to be explored further. A sawtooth-shaped reflecting diffusor placed between cells is proposed. This article addresses the issue in a novel way, primarily because the theoretical range of the optimum sawtooth profile is defined. In the experimental part of the study, the possibility of producing such a profile directly on glass using a CO2 laser is demonstrated. The theoretical model enables discrimination between advantageous and disadvantageous sawtooth profiles. As a proof of concept, minimodules based on the optimum parameters were built and tested for their electrical performance. The result confirms that the proposed sawtooth-shaped reflecting diffusor placed between cells creates cell-to-module power gain. The proposed laser technology can be incorporated into existing production lines, and can increase the output of any photovoltaic technology, including and beyond silicon.

Keywords

• photovoltaic
• CO₂ laser
• float glass
• engraving
• cell-to-module power ratio