CIGS monolithically integrated modules achieve substantial efficiency

In a recent statement, Ascent Solar Technologies, Inc., a developer of state of the art flexible thin-film solar modules, has announced that it has achieved greater than 9.5% efficiency for its flexible Copper, Indium, Gallium, Selenide (CIGS) monolithically integrated modules - making it a substantial leap toward realizing high-performance, inexpensive thin-film solar photovoltaics.

 

The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) has independently verified that the modules measured as high as 9.64% in conversion efficiency. The modules tested at NREL were produced from the company's 1.5MW pilot production line.

 

Ascent Solar Technologies say that the test modules measure six inches wide by one foot long and serves as a building block for portable power and building integrated photovoltaic (BIPV) products. They hope to commercialize flexible thin-film CIGS modules in the future using a plastic substrate to provide light weigh flexible photovoltaic material at low cost.

CIGS currently has demonstrated the highest laboratory efficiency at 19.5% (NREL, measured in earth conditions).

 

CIGS thin-film technologies can be placed on a wide variety of substrate materials making it possible to manufacture very lightweight, flexible solar cells on metals and plastics. To put it into perspective, the thickness of a flexible CIGS device is approximately the same as the thickness of a human hair, making it very flexible and lightweight.

 

While CIGS on metallic foils are a good first step, this class of thin-film product does not fully address the basic needs of the space, near space and terrestrial markets.

 

First, metallic foil substrates generally require that each cell must be manufactured as discrete components which then must be interconnected in series and/or in parallel (similar to how flashlight batteries are stacked) to meet the desired voltage and current output in a module. Second, integrating discrete cells into building materials for roofing, siding, and architectural applications becomes more costly and problematic. While this is merely an inconvenience for earth applications, space applications require significant quality control for each process step of the PV array, thus adding to the cost and complexity of the power system. Finally, many of the metallic substrates can interact with the magnetic fields around the earth. While not a concern for earth applications, any outside forces in addition to gravity that act on the spacecraft means that additional onboard fuels and other resources must be used to maintain proper spacecraft alignment so that sensors and antennas work properly.

 

For years, CIGS technology has appeared the most promising for cheap solar power. The National Solar Technology Roadmap, created by the National Renewable Energy Laboratory, states that steady efficiency improvement could ultimately allow CIGS to achieve the lowest module costs and levelized cost of energy among all PV technologies.

 

Some sources say many companies are having trouble making efficient flat CIGS panels with curving adding another layer of complexity and many contracts are calling for delivery from now up to 2012. Apparently only 3 CIGS-based thin-film manufacturers have managed to start cranking out actual saleable product - Solyndra, Nanosolar and Global Solar.

Ascent Solar believes that a system-level solution is needed to provide space, near space and commercial and residential applications with better performing products than currently available - thus striving towards using one mass produced process for all applications of photovoltaic technology.

 

Ascent Solar has developed proprietary monolithically integrated processing techniques to take CIGS to production on high-temperature plastic substrate.

 

These plastics can survive the manufacturing temperatures associated with thin-film CIGS processing while remaining flexible and electrically insulating. The insulating features of the plastics make it possible to connect individual cells into modules during processing. These advances in CIGS processing significantly reduce the weight, cost, and complexity of PV products - making this latest technology uniquely suited for high volume and low cost for space, near space and commercial and residential applications.

 

For more attend Printed Electronics Europe 2009 .

 

Also read Printed and Thin Film Photovoltaics and Batteries .