Manufacturer innovates with new manufacturing method that slashes production costs in half while increasing product quality. An advanced, open-architecture control system that handled both process and discrete control was a key requirement.
Having a commercially-viable innovation is only the first step in the birth of a new company. The idea leads to proof of concept and then – all things being positive – you have to ramp to full production and that means making the right decisions about your manufacturing and automation processes. Make mistakes here and your existence as a company may be threatened.
This was exactly the situation facing St. Louis, Missouri-based Confluence Solar in 2010. The idea: use the Czochralski method of crystalline growth commonly seen in the semiconductor industry to produce monocrystalline substrates for photovoltaic cells, thus increasing product quality while slashing production costs in half. The challenge: ramp from proof-of-concept to commercial production quickly and smoothly while dealing with the same kind of financial constraints that face any new venture.
“The company’s founders realized that … the Czochralski growth method could be used to cost-effectively grow monocrystalline substrates if used in a semicontinuous production mode instead of the prevailing batch production method,” says Gerry Cahill, chief logistics and information officer for Confluence Solar. “With our unique proprietary HiCz process, we can use a semicontinuous process, which can reduce the cost of producing monocrystalline substrates for photovoltaic cells by a factor of two while increasing the quality over what batch processes can produce.”
With the Czochralski growth method highly pure silicon is melted down in a crucible, usually in an inert atmosphere such as argon and in an inert chamber such as quartz. A seed crystal is then dipped into the molten silicon and slowly withdrawn and rotated. By precisely controlling the temperature gradients, rate of pulling and speed of rotation, it is possible to extract a large, single-crystal, cylindrical ingot from the melt. Unwanted instabilities in the melt can be avoided by closely controlling the temperature and velocity fields during the crystal growth process. This demand for visualization and control makes the automation system a critical element in the operation.
One of the cornerstones of Confluence Solar’s HiCz manufacturing process is the flexibility of an open architecture, says Bia Henriques, senior control systems engineer. “We wanted to make our process control system as open as possible so we could handle as many communication protocols as possible. We also wanted an open architecture so we could be as hardware-agnostic as possible and have a high degree of independence from any one vendor.”
Additionally, Confluence Solar expects to continuously modify and refine the crystal-puller technology in an ongoing effort to optimize the manufacturing processes to perfect all aspects of the process and drive the competitive advantage offered by their innovation to deliver maximum benefits and thus driving a heightened requirement for flexibility and adaptability going forward.
Atlanta, GA-based automation vendor Siemens Automation partnered with its long-time St. Louis area channel partner Frost Electric Inc. to submit a bid based on its Simatic PCS 7 process control system which included engineering and programming, advanced process control consulting services, including Model Predictive Control, all the needed systems integration, on-site training and commissioning.
PCS7 acts as the main controller for a system that includes numerous components for both discrete and process manufacturing environments, including ET200S distributed IO, ET200PRO distributed IO, industrial computers and monitors, and Simatic HMI panels. The ET200PRO IO is IP65 rated and can be mounted directly on the machine. Its small form factor and the fact that it does not need to be placed in a cabinet provided CSI with flexibility and savings on its installation.
“CSI actually started their design with a SIMATIC S7 system in mind,” says Garrett Williams, the Siemens account manager for Confluence. “Eventually they realized they needed some of the features of PCS7 for their system. The fact that our SIMATIC line of automation products is comprehensive enough to include components that can be easily integrated together in a variety of configurations and is all based on common hardware components provided them with the flexibility to be able to scale their system from S7 to PCS7 easily.”
Confluence Solar decided in favor of the Siemens/Frost Electric submission for three reasons, says Henriques. To start with the Siemens solution met the detailed technical requirements while being competitively priced. Secondly, the Siemens/Frost bid offered to create a collaborative environment that would help alleviate much of the pressure on the nascent company’s IT infrastructure. Finally, Siemens and Frost offered to meet the company’s aggressive “go live” deployment deadline – which was just six months out.
Both Cahill and Henriques are pleased with the results so far.
“We’re a company of about 30 people, not an IT house,” says Cahill. “Our core competency is growing silicon crystals. We needed a company that could take on the responsibility of IT and adapt the software to our specifications without using a lot of our own scarce resources.”
Henriques echoes Cahill’s assessment of the Siemens relationship. “We didn’t want someone to just supply us with products and leave it to us to figure out how to use them within our HiCz process,” she says. “Siemens has been working closely with us to help ensure that we get the most out of our process control system.”
According to Henriques, one critical benefit of PCS 7 is how it has helped her and her team turn the knowledge and experience of the company’s crystal-pulling system operators, each of whom has several years of experience, into production algorithms. Those algorithms provide the foundation of the software modules in the PCS 7 Advanced Control System Library which provides the process control software required by the crystal-puller systems. By doing this, Confluence Solar both reduces the reliance on individuals and their knowledge and dramatically increases the consistency of its process which becomes scientifically repeatable.
While careful not to reveal the technical details of the company’s proprietary technology, Cahill and Henriques also agree on an important point: “The PCS 7 process control platform is absolutely essential to enabling us to make our HiCz crystal pulling technology work.”Have an Inquiry for Siemens about this article? Click Here >>