The marketing for Solyndra’s unique tubular module design was top-notch. They used a logo that featured a solar ray-emitting “O” and the tagline “The new shape of solar.” This project cost taxpayers more than $570 million. A critical design review (CDR) could have cost under $50,000.
Critical Design Review
A Critical Design Review (CDR) is a thorough check that assesses a system’s detailed design. It ensures the design meets performance needs. It is also ready for production and testing. The CDR shows that the design is ready to proceed. It also tackles risks and meets specifications.
If a CDR had happened for this design, it could have prevented a massive waste of taxpayers’ money.
Electrical Performance
Solyndra claimed its cylindrical modules could track the sun without costly mechanical systems. They thought the curved shape would catch sunlight from every angle all day. However, sunlight only exposes a small part of the cylindrical cell at any time.
The cell’s back side will never see sunlight. Figure 1: This cross-section view shows the module construction used by Solyndra. The back side of the cell lacks a reflective surface.
As the sun moves across a fixed flat surface, the angle of incidence changes with every moment. Peak output happens only when the sun is perpendicular to the solar cell surface. Solyndra pointed to this as its main selling point.
The sun hits a curved solar cell at right angles for part of the day. But the area that gets this ideal angle is small compared to a flat panel. This means that strong sunlight exposes less photovoltaic material for energy conversion.
It doesn’t make sense to add complexity to solar cell materials when their costs are already low. A second glass tube encased the optical layer, and costs were rising quickly.
A thorough design review could have cost under $50,000. This would have saved taxpayers more than $570 million.
Keep it simple.
My design principle of “Keep It Simple” stands out in the financial failure of Solyndra.
In the end, how did this complex design with poor performance pass the CDR? The choice to proceed was not based on sound engineering principles. This failure could have avoided costs for U.S. taxpayers!
Norman T. Neher, P.E.
Analytical Engineering Services, Inc.
Elko New Market, MN
www.aesmn.org