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Where the rubber meets the road: Skyline Solar puts its faith in the automotive industry

22 October 2009 | By Tom Cheyney | Chip Shots

When Bob MacDonald first told me at Intersolar North America about Skyline Solar’s plans to have the structural components of its high gain solar (HGS) systems built on underused automotive production lines as part of its “off-the-shelf” manufacturing strategy, the proverbial value proposition was pretty obvious. The car industry has long known how to work with metals in volume, rolling, forming, and stamping them in the millions of units, and its assembly lines boast a high level of automation. It wasn’t a stretch to envision Skyline’s reflective racking and mounting elements being cranked through a Detroit-style factory in a relatively low-cost manner--something any budget-conscious solar manufacturer would like.

skyline_cosma3

Since Skyline has revealed its manufacturing partner—the Cosma International unit of the Magna International conglomerate—I wanted to catch up with the venture-backed company’s CEO/cofounder to get into the nuts and bolts of the arrangement.

Skyline has been receiving hardware shipments for a month or so from a pilot line running on Cosma’s Troy, MI, site, he told me during a phone interview. The first facility isn’t rated for megawatt-level output, since volume production is not its primary focus. “Qualifying components, qualifying processes, getting everything fully documented”—that’s what the pilot’s role is, according to MacDonald.

Sometime in the next couple of months Skyline will choose one of Cosma’s existing locations in the U.S. to put that initial processing knowledge to work and deploy its first large-volume production line. MacDonald’s claim that “the design has been specifically detailed so that it can fit into their standard assembly plants” will then be put to the test.

Engineers from the partner firms have been working together for awhile on product design and materials choices. The team “explored different options for structural materials,” he said, and “stamped steel was found to be the most cost effective.” This represents a change in the basic metal used, since Skyline’s earlier system featured aluminum as its structural material.

skyline_macdonald Another area where the Cosma-Skyline engineering squad made a change was with the manufactured length of the reflective panels. The HGS system features 20-foot-long metal pieces, which is an easy length to make and ship. But the automotive guys saw that if the panels were reduced to four 5-foot-long sections, they “could then be stamped in Cosma’s standard stamping presses that are normally stamping materials for the door panels or hood of a sedan,” explained MacDonald (seen at left). The four units can then be put back together into the convenient 20-foot lengths before leaving the factory.

Since two critical elements to maintaining a high quality standard for manufacturing the metallic structures are reproducibility and repeatability, the engineering teams spent a lot of time sequencing the right assembly techniques and optimizing the details in order to dial in a high-throughput, highly manufacturable process. As it turns out, “the mechanical tolerances are well suited for an automotive facility,” MacDonald explained, since the HGS design features a lower solar concentrator effect—about 10X—compared to other CPV systems’ high-concentration schemes.

When asked for some examples of critical tolerances, he said it “mostly centers on the optical performance;” that is, making sure the sunlight hits those horizontally nestled HGS array cells properly. The tracker mechanism and other Skyline unit design elements require “no tweaking in the field,” whereas many CPV systems require said tweaking to get the sun to hit the receiver assembly efficiently. The tolerances that Cosma has to deal with have to do “with the shape of the reflective metal surface and linearity of the system along the trough.”

Next year, Skyline hopes to move from development stage to production. Another funding round is in the works and a DOE loan application has been submitted, according to MacDonald. The company plans to have its first (albeit smallish) commercial system installed in the field in early 2010, and to complete its manufacturing supply chain ramp-up to megawatt-scale volume. The Cosma connection will be one key to how well the fledgling solar firm’s rubber meets the road.