ZSW Sets European Record for CIGS Cells
Scientists at the Centre for Solar Energy and Hydrogen Research Baden-Wuerttemberg (ZSW) in Stuttgart have raised the efficiency of thin-film CIGS solar cells to 22.0 percent by optimising various manufacturing processes.
The Fraunhofer Institute for Solar Energy Systems ISE has confirmed the results. ZSW is now only 0.3 percentage point behind the current world record.
The cell has a surface area of 0.5 square centimetres, a standard size for test cells. It was produced in a laboratory coating machine using the co-evaporation method. "The technological potential is far from tapped out at 22 percent efficiency," says Michael Powalla, ZSW board member and head of the Photovoltaics division. "It will be possible to achieve up to 25 percent in the next few years."
A race between solar power technologies
CIGS technology has made great strides in recent years. It overtook its the multicrystalline silicon cell some time ago in cell efficiency, extending its lead to a full percentage point. In module efficiency, silicon PV is still ahead. Commercially available modules have about 17 percent, CIGS modules about 14 percent.
Manufacturing costs amount to 40 cents per watt even in small CIGS factories, and they can be reduced by expanding production capacity. Given an annual output of 0.5 to 1 gigawatts, CIGS PV plants can achieve 18 percent or greater module efficiency and costs as low as 25 cents per watt. This means costs can be brought down to a competitive level even at a relatively low output, so it follows that CIGS PV manufacturing requires less upfront investment than silicon PV production.
Market opportunities for thin-film photovoltaics
For people who own solar power systems. the ability for thin-film modules to deliver higher yields under low light conditions is a major selling point. It also takes less energy to manufacture CIGS modules than silicon PV. Flexible versions featuring high-efficiency CIGS are in the works.
The efficiency rates achieved in the southwest of Germany are also of interest to the industry. Manz AG, ZSW's industry partner, recently decided to continue its commitment to CIGS and is developing this technology further in a joint effort with ZSW.
A record amount of solar power capacity, 52 gigawatts, was installed in 2015, and annual demand is expected to rise to more than 100 gigawatts in the next few years. And that means the world will be needing new solar factories.
