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Hemlock Semiconductor

Hemlock Semiconductor Group needed more power to fuel its energy-intensive production processes, so ITC formed a dedicated project team to to upgrade transmission facilities.


Manufacturers across the globe rely on Hemlock Semiconductor (HSC) as a reliable source for polycrystalline silicon, one of the purest man-made substances on Earth. HSC is a world leader in producing this high-purity product for electronics, solar cells and semiconductors. 

A growing demand in the solar market created a need for HSC to expand its manufacturing capacity, resulting in a need for significant power increases. For HSC, maintaining the highest quality during the manufacturing process is critical; even the slightest power flow interruption can result in immediate product loss plus risks of equipment damage and possible safety issues. Even the slightest momentary outage could trigger weeks or months of work to requalify a product for the customer. 

HSC’s load requirements are by far the highest in Michigan, so the company needed to be sure it would have a reliable source of high-voltage power throughout the manufacturing expansion and on into the future. HSC enlisted ITC’s expertise in high-voltage industrial interconnections to help with long-term planning for the project. As HSC continued to expand its production and ITC provides upgrades to meet the company’s needs, new issues occasionally emerge which the HSC-ITC team addresses as needed.


HSC partnered with ITC to design a comprehensive system, including a new dedicated substation, capable of consistently delivering the high-quality power needed to operate the facility and maintain reliability during the planned series of facility expansions. ITC established a project team dedicated to HSC, and maintained management oversight and consistent communication to provide a long-term planning perspective throughout the project. ITC works with HSC to coordinate planned outages in a way that does not negatively impact production, and established a process to keep existing HSC facilities working with minimal interruptions during the expansion process. 

ITC conducts quarterly meetings with HSC to ensure planned outage impacts to their operations are minimized. Any unplanned events are reviewed to determine the root cause and, most importantly, to determine a course of action that will minimize the risk of the event being repeated.

“Having ITC as part of the process meant the system could be examined with a long-term view in mind, which was critical for minimizing production disruptions and lost product during the transition period.”

– Rod Williamson, Global Energy Category Manager, Dow Corning/Hemlock Semiconductor


The HSC expansion was a success with minimal interruption to manufacturing. ITC’s transmission system upgrades have delivered the necessary high voltage capacity and reliability ever since implementation. ITC and HSC continue to work together to ensure that ITC delivers the high-quality energy HSC needs to provide its customers with high-quality products. ITC and HSC continue to meet quarterly, and additional meetings may be called to address new issues or concerns. As examples, ITC has conducted a study to investigate the harmonics impact from an ITC-owned 75 MVAR capacitor bank. And ITC is working with HSC to develop an action plan to address high voltage-low load impacts from a nearby generation facility.

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