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New process developed for high speed manufacture of CIGS solar cells

Editorial
article image CIGS solar cells

Midsummer has developed a high speed process for manufacturing CIGS solar cells utilising sputtering of all layers in the solar cell structure. Midsummer is a leading supplier of production lines for cost effective manufacturing of flexible thin film CIGS solar cells. 

Midsummer recently achieved 15 per cent active area efficiency on an entire 225cm² solar cell using this sputtering technology. By using sputtering in all processing steps, the process cycles in the manufacturing of solar cells can be drastically shortened, the solar cells made cadmium-free and also made on stainless steel substrates suitable for flexible modules, all contributing to a highly competitive method to manufacture thin film CIGS cells with high efficiencies.

The process is a completely dry process as well as an all-vacuum process, with less stringent requirements for cleanrooms and similar environments. 

Sven Lindström, CEO, Midsummer explains most photovoltaic experts consider thin film flexible solar modules to be the future of solar energy. Midsummer’s unique process makes thin film CIGS solar cells even more commercially attractive by making it possible to manufacture solar cells quickly, efficiently and cost effectively even in small volumes.

To prove the potential of the technology, Midsummer recently made cadmium-free CIGS cells with 15.0 per cent active area efficiency on the entire solar cell, sized 225cm². The solar cells were made on stainless steel substrates, stamped out from 0.3mm thick ordinary ferritic stainless steel. The buffer layer was sputtered instead of being deposited with chemicals or by atomic layer deposition. The CIGS layers were also sputtered from compound CIGS targets resulting in a very short cycle time.

Using Midsummer’s revolutionary solar cell manufacturing process by sputtering, solar cells can be made on stainless steel and without any cadmium in the buffer layer. Cadmium and its compounds are highly toxic and exposure to this metal is known to cause cancer and other illnesses; therefore avoiding cadmium in the manufacturing process is desirable.

With its expertise in utilising sputtering for fast and efficient manufacturing processes, Midsummer has developed production lines for highly efficient and cost effective manufacturing of flexible thin film CIGS solar cells. 

The company’s Duo turnkey system is a scalable and compact manufacturing system for solar cells with a 5 MW annual production capacity. The heart of Midsummer’s photovoltaic production system, the Duo line is a sputter tool that deposits all the layers forming the finished cell. 

Midsummer’s CIGS cells look like crystalline silicon solar cells, but are made on stainless steel substrates, making the cells suitable not only for regular solar panels, but also for flexible, lightweight panels that can be used on membrane roofs, landfills or other structures where traditional glass modules cannot be applied.

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