Kayex furnace design yields cost effective solar cell wafers

Situation:

Demand for alternative energy sources is growing. However, manufacturers in the solar industry have found it difficult to meet the demand for their technologies in a cost effective way — particularly in the case of solar cells. This has been due, in part, to the high costs of producing single-crystal silicon (also called monocrystalline), the base materials used in the cells.

Challenge:

Considered one of the most efficient materials for converting solar energy to electricity, monocrystalline ingots are produced in crystal-growing furnaces. These are the same furnaces used to grow the single crystalline wafers for the semiconductor industry — a much larger industry and the one for which most crystalgrowing furnaces are 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 cleanliness and quality control, 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.

Mechanisms for comfort cooling are big energy users; the retailer needed a cooling solution that required significantly less energy but would still meet its design requirements — including aesthetics and reduced noise.

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 — with the help of Kayex, an SPX company.

Based in Norway, NorSun is a leading supplier of silicon wafers for high efficiency solar cells. As part of its plan to make manufacturing solar cells more economical, the company constructed a new facility in Ardal, Norway. Plans for the plant included 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 NorSun reached out to for assistance was Kayex, which is recognized for developing and manufacturing crystal-growing furnaces for both the semiconductor and solar industries.

At the time, the Kayex engineering team was already applying its expertise in the semiconductor industry to the design of a Kayex furnace geared specifically towards the needs of the solar industry. Working with Norsun, Kayex engineers further modified this design to fit the specifications that NorSun had determined would best meet its objectives.

The new Kayex design 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, the Kayex team reduced costs by eliminating the extraneous design details that weren’t required for producing solar cells.

Results

The tight launch schedule for the new Norsun 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 late 2006; equipment shipped in 2007 to meet the plant’s opening date in mid-2008.

The Kayex team was able to find a freight company specializing in transport to Scandinavian countries to help expedite the process. They also reduced costs and shortened installation time by hiring local contractors in Norway to assist the Kayex team with on-site installation.