Design and Development of a Nd:YVO4 Laser Edge Isolation (LEI) System for Solar Cells
S. Messaoud, N. Moussaoui, H. Lahmar, F.S. Serir, R. Boushaki, D. Ouadjaout, A. Messaoud and B. Djoudi
This paper describes the design and the development of laser edge isolation (LEI) system for Si solar cells. It consists of a Q-switched 532 nm Nd:YVO4 laser source, an optical set up, a system motorized (X-Y) linear stages, a cell fixing system based on vacuum chuck, a camera to visualize the working zone and a He-Ne laser source for optical alignment. The command and control of the LEI system is ensured by a LabVIEW program and National Instruments (NI) devices. The designed system allows the positioning of the continuous isolation grooves very close to the edges leading to maximize the solar collection area and thus the efficiency. The proposed and developed approach consists to integrate a square shape unity file into the main program with a variable magnification factor, K. In order to demonstrate the operational and functional capabilities of the designed LEI system, series of experiments were conducted, scribing of continuous isolation grooves along four sides of multi crystalline Si solar cells with an area of 100 mm x 100 mm and a thickness of 320 μm to achieve electrical EI. It was shown that the grooves are well continuous and the measured values of continuous grooves lines width and depth are in the range of a typical groove dimensions. The voltage-current characteristics of the solar cells front side EI were analysed using a solar simulator. From our measurements result, we find that the best efficiency equal to 10.4 and the highest fill factor (FF) equal to 67 % ensure a satisfactory edge isolation (EI) of the solar cell.
Keywords: Nd:YVO4 laser, He-Ne laser, Si solar cells, LabVIEW, laser edge isolation (LEI), laser scribing, shunts