Thursday, June 3, 2021

How to Improve Solar Performance? Benchmark and Share Best Practices

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Growing Area of Collaboration Informs Operations, Maintenance, and Business Decisions at Large-Scale Solar Plants

At the end of 2019, Wood Mackenzie reported a cumulative solar photovoltaic (PV) capacity in the United States of more than 75 gigawatts*—about 75 times the installed capacity in 2010. With an expected operating life of 20-plus years, most of today’s plants haven’t reached the halfway mark. Given this relatively limited operational experience, more knowledge is needed about plant performance across fleets and over time.

To address this, EPRI is leading an industrywide benchmarking effort through which PV owners and operators can share data and insights about performance, operations, maintenance, vegetation management, technology trends, and other topics.

“Many companies are adding new PV plants to their generation fleets and in some cases are venturing into PV for the first time,” said EPRI Principal Project Manager Michael Bolen. “EPRI’s initiative enables them to benchmark plant performance based on industry data and determine what can be done to increase plant production and reliability.”

While EPRI has been evaluating PV performance for a decade, only recently have enough commercially operating large-scale PV plants collected and shared data for substantive benchmarking. Through this broad benchmarking, participating plant owners provide EPRI with on-site meteorological and production data via secure communications. For each plant, EPRI checks the data for quality, uses them to calculate various metrics for actual and expected performance such as capacity factor and performance ratio, and compares the results with other participating plants. Additional analytical techniques are being developed to quantify and benchmark PV plants’ performance loss and degradation rate over time. More than ten fleet owners currently participate, and the aim is to increase that number significantly.

EPRI has launched the Solar Owners League, which will manage these benchmarking efforts, provide a forum for sharing technical knowledge, and develop and apply analytical tools for benchmarking performance and reliability. EPRI plans to launch a benchmarking website that enables users to analyze data in various ways—such as comparing a plant’s performance with others in a specific region or comparing the performance of fixed-tilt plants with single-axis tracking plants. While the website will offer some publicly available information, access to the website’s benchmarking component will be limited to members of the league.

Duke Energy Renewables (Duke Energy’s project development arm) owns and operates more than 850 megawatts of PV at more than 50 solar plants across the country and recognizes the value of EPRI’s benchmarking initiative.

“Because solar is still relatively new and uncharted, it’s difficult to obtain reliable benchmarking,” said Josh Rogers, who directs commercial operations for Duke Energy Renewables, the utility’s project development arm.

Rogers said that EPRI’s initiative has provided Duke Energy Renewables with a better understanding of issues such as degradation rates. Insights gained through benchmarking have also helped Duke Energy Renewables prioritize maintenance tasks. For example, if a minor problem does not significantly affect energy production, deferring repairs until the next maintenance cycle may be more cost-effective than immediately dispatching a technician.

Effective vegetation management at PV plants can prevent fire hazards, enable maintenance technicians to access equipment, and help owners comply with jurisdictional siting requirements. Rogers reports that the opportunity to exchange experience with various vegetation management strategies in various regions has informed Duke Energy Renewables’ management approach.

In addition to improving plant performance, benchmarking can inform business decisions. “When plant owners and operators have data-driven insights into long-term plant performance, they can make better decisions throughout the lifetime of their plants,” said Bolen. “For example, benchmarking can inform decisions about plant designs and equipment best suited for a particular region as well as decisions on when to re-power, re-configure, or decommission plants.”

During monthly Solar Owners League webcasts, leaders in plant management, operations, and maintenance share knowledge and discuss collaborative research opportunities. The first webcast highlighted EPRI’s public release of the report Large-Scale Solar Photovoltaic Plant Performance and Degradation Benchmarking, which found that large-scale PV plants seem to lose nameplate power at a rate of 1% per year—greater than the 0.5% per year that is often assumed. More research is needed to identify and quantify the root cause of the loss and determine if the lost power is recoverable.

“EPRI’s benchmarking efforts serve the greater good of our industry,” said Rogers. “They drive a productive conversation among peers, which in turn informs future business decisions and manufacturing and equipment advances.”

*Wood Mackenzie Data Hub, U.S. PV Market Forecasts

Key EPRI Technical Experts:

Michael Bolen
For more information, contact