Copper Grid in Solar Cells
Using copper instead of silver to create the electrical contact lines on solar panels is one of the in-vogue technologies these days, judging by a panel that devoted to commercializing this process at Intersolar in San Francisco this week. The discussion focused on different approaches to lay down the copper grid, in particular those that deviate from the conventional screen printing method for creating the silver contact lines.
The material is cheaper and more readily available compared to silver, which has been the industry choice for creating the grid that ferries electrons produced by the cells. Solar panel makers are understandably ultra sensitive to production costs nowadays, given the crazy drop of solar panel prices thanks to a glut of them over the past two and a half years. Silver costs about 560 euros per kilogram, while copper can be had for 7 euros per kilogram.
Screen printing has been the conventional method of creating the electrical contact lines. With copper, factory tool makers have rolled out plating equipment, which can create thinner lines faster and at lower temperatures (750-800° Celsius v. 350-400° Celsius).