Shugar: Getting to a PV-Supported Grid

By, Seth Masia

“That article had impact. It changed the direction of utility PV from remote systems to distributed grid-tied systems. It was a key step toward net metering.”

In 1989, Dan Shugar was a transmission planner doing grid applications for Pacific Gas & Electric (PG&E). Summertime peak loading was a persistent problem: It overheated transformers and conductors. Rather than undertake a costly overbuild of isolated systems, Shugar calculated that photovoltaic arrays of about 500 kilowatts (kW) could be sited to balance those peak loads.

In May 1990, he presented a paper on these calculations to the 21st IEEE Photovoltaic Specialists Conference, predicting that as the cost of PV came down, peak-shaving would be a profitable way to use the technology. SOLAR TODAY ran a condensed version of the paper in our September/October 1990 issue.

The paper led to a set of real-world experiments. Grid-support trials were undertaken by PG&E at the PV for Utility Scale Applications (PVUSA) array in Kerman, Calif., and by seven other utility companies around the country. A key test put a 675-kW PV system at the end of an overloaded transmission line. The results showed conclusively that PV is a cost-saving approach to peak-shaving.

With Howard Wenger and Greg Ball, Shugar described the work in a feature article in the September/October 1993 issue of SOLAR TODAY, titled “Photovoltaic Grid Support: A New Screening Methodology.”

Don Shugar
Shugar | Published in SOLAR TODAY, March 2010, “Tesla: The First 48 Hours.”

“That article had impact,” Shugar now says. “We showed empirically measured benefits including cooler transformers and more stable voltage. It changed the direction of utility PV from remote systems to distributed grid-tied systems. It was a key step toward net metering.

Maureen McIntyre, [then] editor of SOLAR TODAY, was great to work with and endlessly supportive.”

Shugar went on to help launch Advanced Photovoltaic Systems, a pioneer in thin-film manufacturing, and eventually was president of SunPower. Today he is president of Solaria. Along the way he has written several more influential feature articles for SOLAR TODAY. Most recent: “Tesla: The First 48 Hours” (March 2010).

Where will solar go in the next 25 years? “We’ve actually modeled this,” Shugar said. “PV will be the single-largest form of new energy by 2020, and within 25 years will be the largest form of peak power in the grid.”

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