New project to identify damage to photovoltaic systems and develop solutions

Two decades ago, solar energy capacity in snowy northern regions was almost nonexistent. Today, because of dramatic cost drops, some of the fastest-growing regions for photovoltaics are now above 40 degrees north latitude, where snow is abundant in winter.

Snow and ice can physically stress modules, resulting in breakage. Moreover, while snow on the ground is highly reflective and can boost photovoltaic solar energy output, snow that covers the panels blocks sunlight from reaching the solar cells. Estimated snow losses, or the energy lost when snow shades photovoltaic panels, range from 1% to 15% annually and can reach as high as 90% in a month, depending on specific climatic and system design factors. At that scale of loss, major snowstorms that sweep across the country can reduce solar generation at a regional scale.

The snow-photovoltaic nexus

Over the past six years, Sandia has emerged as a leader in the study of snow and its effects on photovoltaic performance and reliability at northern latitudes, with funding from the DOE Solar Energy Technologies Office.

Working with the University of Alaska-Fairbanks and Michigan Technological University, as well as multiple industry partners, Sandia has advanced research on the snow-photovoltaic nexus. This research includes development of advanced snow-performance models, identification of technologies and designs to accelerate snow shedding, and development and deployment of monitoring stations to measure the amount of light that passes through snow and the weight of snow on photovoltaic panels.

“Snow on PV systems presents a unique challenge,” said Sandia scientist and principal investigator Laurie Burnham. “Not only is snow ubiquitous in the northern U.S. in winter — and therefore, seasonally predictable — it is a repetitive and persistent stressor. Our team is making important strides toward shifting the industry away from a one-size-fits-all approach to photovoltaics by generating the data to support the adoption of solar designs and technologies that are more efficient in wintry climates.”

Understanding solar infrastructure in severe weather

The current three-year project, “Increasing the efficiency and resilience of PV systems in Northern Regions,” will formally end in September but then immediately expand into a broader effort aimed at securing the nation’s solar infrastructure against severe weather, including snowstorms.

Sandia will lead the new three-year DOE-funded project, “Securing solar technologies through optimization, resilience and modeled systems,” known as SSTORMS. The Sandia project team will include Laurie Burnham, Dan Riley, Bruce King, Thushara Gunda and Nicole Jackson.

Lawrence Berkeley National Laboratory and the National Renewable Energy Laboratory will contribute to the project, which will focus on identifying physical damages to photovoltaic systems and components caused by specific storm categories, developing technical solutions and hardening strategies to ensure resource availability, and disseminating best practices to stakeholders.

Like Sandia’s snow-focused research, the SSTORMS project will investigate the performance and reliability of photovoltaic power plants in the context of global climate change and the associated increase in the frequency and severity of extreme weather events. Extreme weather events can inflict catastrophic damage on photovoltaic systems, including the shattering of glass and collapse of racks, that can cause the destruction of individual modules or even whole systems.

Damage can also be subcatastrophic, such as internal damage to the solar cells or other module components that may not be detected through a visual inspection. Undiagnosed damage may worsen over time, resulting in accelerated performance degradation or the accelerated aging of module components. Such damage is only detectable with costly diagnostic techniques like infrared or electroluminescence imaging.

The team will investigate both damage categories to identify vulnerabilities and opportunities for storm-hardening. They will also create a risk index to inform future photovoltaic siting and design decisions and create resource adequacy models to ensure sufficient generation in a solar-dominant energy future. Storm categories of greatest interest to the team are hurricanes, floods, tornados and hail, in addition to snow.

“This is the time,” Laurie said, “to take an objective and thorough look at the reliability of our solar infrastructure in the face of global climate change and increased storm activity and make sure it is robust. Our new project aims to do just that.”