Next year, solar PV module makers will have the option of working with a new technology to replace silver bus bars with a customizable copper mesh, which will reduce silver usage, increase power output, and allow for lighter modules.
With its Merlin technology, GT will be one of at least three PV equipment makers to offer a copper mesh or wire solution for PV cell metallization and interconnection. This announcement follows only a week after Meyer Burger revealed its first order for its SmartWire technology for a PV factory in Poland.
GT is already working with select customers to implement Merlin, which involves custom-made copper meshes soldered on to PV cells instead of busbars. Like competing designs, the most obvious and easily quantifiable benefit of the technology reduction in silver use up to 80%, which translates directly into cost reduction.
However, there are multiple other benefits. These include less shading by busbars and more electrical connections on the surface of the cell, which GT says increases power output by 3-5% compared to standard modules.
Also, cells using mesh grids are less susceptible to power losses from microcracks. The grid provides an exoskeleton on the front and back of the cell to allow for more flexibility in PV modules, as well as for lighter module designs.
This in turn translates into lower installation, shipping and balance of system costs. We wanted to come up with a solution that hits across the entire value chain, notes GT Senior VP and General Manager Dr. Venkatesan Murali. The downstream advantage is easily as large as the silver reduction.
These advantages are shared by other copper mesh designs. However, GT stresses that its approach utilizes a customized copper mesh soldered to the surface of the cell using standard soldering techniques, instead of copper wires embedded in layered elastomer.
Not only does this allow standard materials, but the mesh grid can be customized into designs to assist the evacuation of electricity, including additional busbars where the current builds up at the cell edge. It is a more efficient way of taking current off of the cell, explains GT Director of Marketing and Communications Jeff Nestel-Patt.
GT’s method of providing this solution also differs from its competitors. The company will produce and sell customized copper meshes to customers, and expects to reach a production capacity of 100 MW annually by the end of 2014. In early 2015 it will begin to offer a wire attachment tool to customers, which will replace the tabbing stringer.
This tool can be integrated into existing production lines or new lines, and GT notes that the technology is completely cell agnostic. And as Merlin makes PV cells more flexible and durable, this allows the use of thinner wafers.
GT says that it has received a strong response from its customers, some of which are already working with Merlin. We have strategic customers who are already participating, notes Senior VP Murali.