June 12, 2008 – Vitex Systems says it has achieved a “key breakthrough” in protecting flexible copper indium gallium selenide (CIGS) solar cells with its “Flexible Glass,” achieving 1100 hrs of testing in high-temperature and humidity conditions with stable efficiency.
CIGS has shown promise to achieve production efficiencies using low-cost roll-to-roll manufacturing, but like cadmium telluride (CdTe) cells they are sensitive to moisture and oxygen, and commercially-available flexible CIGS solar cells typically carry a lifetime guarantee of only a couple of years, the company notes. Encapsulating in rigid glass extends that lifetime but also adds weight and costs (production and shipping/installation) as well as less flexibility in packaging.
The CIGS cells used for the 1100hr tests at the Pacific Northwest National Laboratory were made on stainless-steel foil laminated with Vitex’s Flexible Glass 200 (thickness ~0.3mm) with a proprietary lamination process. Samples were exposed to damp heat (85°C, 85% relative humidity) for >1000 hrs. They were shown to maintain >98% of their original efficiency after 1100 hrs, exceeding requirements of the International Electrotechnical Commission’s (IEC) 61646 standard, the company noted.
Tests are continuing to determine the devices’ ultimate lifetime, though Vitex’s Chyi-Shan Suen, director of business development, notes that early internal tests have extended to >4000 hours under such conditions, maintaining ~80% of the cell’s original performance. The company is now seeking licensees to manufacture and commercialize the Flexible Glass 200 films to widen availability to more solar-cell manufacturers.