News

25 September 2009

 

Sunovia claims CdTe solar breakthrough

Researchers working on thin-film cadmium telluride (CdTe) solar cells say that they have set a new world record for the open-circuit voltage of these types of device.

If confirmed, the advance could increase significantly the power output possible with CdTe cells, helping to make them more competitive with traditional energy sources.

The research team, which comprises engineers from Florida-based Sunovia and its Illinois-based partner EPIR Technologies, said that its single-junction CdTe cells showed an open-circuit voltage of 1.34V. In a two-junction configuration, that figure of merit increased to 1.75V.

“[These] single-junction and two-junction devices exceeded the highest open-circuit voltage values ever reported publicly by research institutions on thin film CdTe solar cells by over 45%,” they claim.

However, the companies make no reference to any pending publication of their research in a peer-reviewed journal, or any verification of the result by an accredited test lab such as the National Renewable Energy Laboratory (NREL). Until then, their claims will inevitably attract some skepticism.

Nevertheless, the open-circuit voltage is an important figure of merit because the amount of electric power that a cell can generate follows Ohm’s law. The claimed 45% increase could, in theory, lead to an equivalent increase in output power – assuming that other cell characteristics remain constant.

Michael Carmody, EPIR’s director of photovoltaic materials development, says that the increased voltage will ultimately make CdTe cells competitive with multi-junction devices based on III-V materials – currently by far the most efficient cells in volume production,

“The company’s two-junction II-VI-on-silicon design will reach production efficiencies [of] over 35%,” Carmody predicted, adding that the production cost would be only a small fraction of that for three-junction III-V solar cells. “Three-junction II-VI-on-silicon cells will have even higher production efficiencies without much added cost.”

Sunovia’s plan to use silicon substrate material is at odds with the method favored by First Solar, the company that currently dominates the CdTe solar scene. First Solar uses glass substrates and its latest figures claim an average module conversion efficiency of just under 11%.

See related items:

Sunovia and EPIR complete closed space sublimation system

Sunovia and EPIR expanding R&D and pilot manufacturing facility

Second DOE contract for Sunovia/EPIR targets IR detectors

DOE selects EPIR/Sunovia’s CdTe-on-Si PV technology

Search: Sunovia EPIR CdTe/Si

Visit: www.sunoviaenergy.com

Visit: www.epir.com

The author Michael Hatcher is a freelance journalist based in Bristol, UK.