Kayex Furnace Design Yields Cost-Effective Solar Cell Wafers

Situation

Demand for alternative energy sources such as solar power is growing. However, manufacturers in the solar industry have found it difficult to meet this demand cost effectively. This has been due, in part, to the high costs of producing the base materials used in solar cells — single-crystal silicon (also called monocrystalline).

Challenge

Considered one of the most efficient materials for converting solar energy to electricity, monocrystalline ingots are produced in Czochralski crystal-growing furnaces. These are the same furnaces used to grow the single crystalline material for the semiconductor industry — a larger industry and the one for which most crystal-growing furnaces were designed.

While the wafers used in the semiconductor industry can be made into excellent high efficiency solar cells, they are generally considered to be too expensive for large-scale mass production. Semiconductor fabrication has stringent requirements for defects, uniformity, and cleanliness, which result in complex equipment specifications and high manufacturing costs.

The production requirements are more relaxed for the solar industry, where the goal is to generate maximum quantities in the shortest amount of time.

Solution

One way to lower solar cell manufacturing costs is to reduce the costs specifically associated with meeting semiconductor manufacturing requirements. A European company decided to take on this challenge by optimizing their production process and reducing material costs.

Their plan included construction of a new facility in Norway equipped with crystal-growing furnaces that could produce the quality of single-crystal silicon ingot desired but without the extraneous components and design details required of equipment used in the semiconductor industry. Among the companies they reached out to was Kayex, an SPX brand recognized for developing and manufacturing crystal-growing furnaces.

The company had already begun applying its expertise in the semiconductor industry to the design of a furnace geared specifically towards the needs of the solar industry.

Working with the European customer, Kayex further modified this design to fit the specifications the customer had determined would best meet their objectives.

They incorporated a chamber that could accommodate a longer ingot (see "How to Grow a Crystal"), which would result in the creation of more silicon wafers. At the same time, they reduced other dimensions and eliminated details from the design that weren't needed — further reducing costs.

The Extra Steps

The customer's tight launch schedule for its new facility required that Kayex take the new furnace through a rapid design phase, build and prototype it quickly and ship almost immediately. The design was started in late 2006; equipment shipped in mid-2007 to meet the plant's startup date in late 2007.

The Kayex team was able to find a freight company that specialized in transport to Scandinavian countries, further expediting the process. They also reduced costs and shortened installation time even more by hiring local contractors in Norway to assist the Kayex team with on-site installation.

Results

The European customer expects to be at or near full production capacity at their new plant as of January, 2009.

Kayex has since leveraged the new design to secure two additional contracts (one in Korea and one in the U.S.). The company has also launched a new series of crystal-growing furnaces specifically for the solar industry.