The first new process developed by 1366 Technologies produces grooved busbars that prevent light from being reflected out of a solar panel. Instead, the grooves cause light to be redirected along the glass on top of solar panels. That light can then be absorbed by unshaded areas of the solar cell.
The second process improves the cell’s electron-conducting fingers. Although these silver lines are much narrower than the busbars, there are many more of them on a solar cell, and together they shade a significant portion of the silicon. Sachs developed a process for making much narrower lines without sacrificing their conductivity. Instead of using conventional screen-printing technology, his process involves etching troughs into the surface of the silicon and depositing silver particles into the troughs. Metal is then added to these particles via electroplating to build up the fingers. The trough keeps the lines narrow but allows the silver to be stacked relatively high, maintaining conductivity. Typically busbars and fingers shade 9 percent of a cell surface, 1366 Technologies says, but with the company’s new processes, this shading can be reduced to 2 percent. Others have developed techniques for reducing shading, but these have been expensive.
The third process decreases the amount of light reflected off the surface of the cell’s silicon by texturing its surface. This is an approach that’s been taken by others, but the texturing is done in a very regular pattern that creates less surface area than other approaches. Surface area is a problem in solar cells, because electrons are often trapped at the surface of materials, Sachs says.
Because 1366 Technologies’s processes can be incorporated into existing manufacturing lines, they could be adopted by solar cell manufacturers quickly and inexpensively, Sachs says. The company is working to further decrease the width of the silver fingers and improve the texturing, with the goal of reaching an efficiency of 19 percent.