Engineering Team Designs in Reliability from the Start

Jul 17, 2014

Engineering Team Designs in Reliability from the Start

Enphase is, at heart, an engineering-driven company. The Enphase engineering team spans several different disciplines, with hardware, software, semiconductor and mechanical teams dedicated to designing, developing and improving the company’s microinverter systems. They come from various technical and manufacturing backgrounds, including automotive, hard disk drive, telecom and enterprise software, bringing a wealth of valuable experience. What they all share is a commitment to quality and an unwavering focus on reliability and continuous improvement.

“Our rules state that each successive generation has to produce better performance results than the previous generation,” explains Greg Steele, senior vice president of engineering. “We can show you that the exact same generation of product has been successively improved each of the last three years. We can also show you that the one we’re working on is producing even better results than that.”

Enphase’s relentless pursuit of quality starts at the beginning of the product development cycle in textbook “design for manufacturability” (DFM) style. Steele notes the importance of the tight cooperation between the engineering and manufacturing teams early in the stage-gate process. “You have to design the exact automation strategy way up front; you can’t automate after the fact. We automate for very interesting reasons: we automate not so much for cost as for reliability because it makes things so consistent and precise.”

This level of precision drills down to the most seemingly mundane components. “We can tell you the torque of any screw in any unit we’ve ever built by serial number,” Steele says. “We use medical-level traceability in the products that we build. We have traceability down to the date code, lot code, of every part number that goes in the system. When we see a performance issue in the field, we can actually go back and figure out what date code and lot code of part it was that went into that unit serial number.”

Other smart applications of best practices from other industries abound at Enphase. Steele has brought onboard veteran automotive engineers, and their experience has helped the company refine and accelerate its quality and reliability efforts as it ramps up annual production into the many millions of units. “One of the guys I hired was tasked with implementing an automotive supplier quality model called PPAP, or production part approval process, which ensures that the supplier can build at rate before you ever approve them. We have adopted that same process within the rest of our supply chain.”

Steele cites the many “checks and balances in the factory” related to product qualification and overall quality, such as the design verification test (DVT) “that proves the product meets the specifications for which it has been designed.” Once products pass DVT, they are sent to the company’s quality and reliability testing facilities for “product PV,” or product verification testing, where they are run through a regimen of damp heat and temperature cycling as part of the rigorous million-hour reliability demonstration testing. Ongoing reliability testing continues on the factory floor, with samples pulled from the line on a weekly basis to ensure product quality.

Steele’s purview also includes software design and development, which benefits from an agile process that incorporates very short cycles. “With our web-based system, Enlighten, we release something to the field every two weeks. Using agile development, it means we have almost one quality assurance engineer for every two developers, where we’re developing code and real-time testing it. We code during the day, and run them on test beds during the night.”

Whether it’s the software or hardware components of the Enphase solar energy system being designed and developed, Steele knows that setting a very high quality bar comes with the territory. “With industry-leading warranty protection in each of our global markets, there’s no detail that can be overlooked anywhere.”

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