LAZAR

What it does

LAZAR machine combines two significant solar cell manufacturing improvements: A laser cutting technique that minimizes potential shunting of solar cells in addition to a corrective step to remove already existing shunts.

Your inspiration

The energy potential of the sun is immense, but despite this unlimited solar energy resource, harvesting it is a challenge mainly because of the limited efficiency of the array cells. Although recent breakthroughs in the technology of solar cells shows significant improvement but the fact that the maximum solar cell efficiency still falls in the less than 20s% range shows there are enormous room for improvement. One of such room is repairing defected solar cells, thus increasing the cell effective lifespan. In addition to replacing conventional solar cells cutting mechanisms with laser cutting which minimizes process induced shunts.

How it works

The machine is intended to operate under three modes of operation. According to the user choice the machine can either cut, isolate shunts or perform both on a solar cell. An interactive user interface handles all operations and decision making. In the cutting mode, the user is allowed to choose the cutting size from a set of standard solar cells sizes, which are translated to CNC X-Y coordinates along which the laser moves. If the correction mechanism is selected, the solar cell undergoes a thermal scan to locate and evaluate the severity of existing shunts (defects). The diagnostic information is then sent to the main decision unit, which decides whether or not correction will take place. To repair the cell, the laser is intended to pass on the silver lining on the front face of the solar cell, grooving the silver fingers and thus electrically isolating the shunted region from the rest of the solar cell.

Design process

Our vision was to implement a commercial laser CNC machine with a simplified architecture, thus seeking both design ergonomy and energy economy. A technical background has been established about laser technologies and their use in solar cell customization. Different shunt types, their origins and their degrading effects on solar cell performance have been investigated as well. The initial iteration of our prototype involved making a choice of fail-safe commercial equipment. The hardware frame sketch involved three metallic orthogonal axes with mounted stepper motors for automated precise smooth motion. The fiber laser choice was made to cut silicon with minimal loss or damage, power consumption was also a major consideration. The first design was successfully tested to cut commercial standard solar cell sizes. Later, our design was improved to incorporate the defect correction mechanism, where thermography was chosen as a thermal imaging technique since we found it easier to mount a thermal camera on the overall setup. For safety concerns, an alarm system was added to the control unit. Finally to enhance the user experience, an interactive user interface application was added to the process.

How it is different

Laser cutting is widely used today as an efficient alternative to conventional mechanical methods in cutting solar cells. After research, it was found that the solar cells laser cutters only existed as large scale industrial machines. Our proposed design is the first commercial, compact, user-friendly solar cell laser cutting machine. While the fixing of shunts using laser solution was only implemented in research, LAZAR comes as the first automated machine that repairs solar cells by exploiting laser properties such as cutting precision, positional accuracy, improved edge quality and high repeatability.It is worthy to note that the solar cell conversion efficiency has increased by 1.465% after shunts isolation. The results indicate that this isolation has a potential to effectively fix solar cells.

Future plans

The overwhelming response to LAZAR from the sustainable tech professionals in the region, sharing their view of how they see it as a revolutionizing tool to the cells' conversion efficiencies, has inspired us to take the current design to the next level. While many cutting operations can be completed through three cutting axes, two extra axes may be required when operating on the rear contact sides. Another improvement is to an additional mechanism which evaluates the solar cell electrical performance after cutting and correction operations take place. Thereby, ultimately ensuring a reliable customization process on the solar cells.

Awards

1st Prize Winner at the "13th UAE IEEE day Annual Competition" 1st Prize Best Senior Design Project in the Electrical and Computer Department, University of Sharjah