Advancing informed visual impact analysis and mitigation

Visual Impacts of Utility-Scale Solar Energy Facilities on Southwestern Desert Landscapes

Field observations of solar facilities revealed that the facilities are visible for long distances and may cause a wide variety of visual contrasts, including glare and dynamic color variation.

Because of their large size, strong regular geometry, and highly reflective surfaces, solar energy facilities may contrast strongly with the natural or rural settings in which they often are located. In the open desert landscapes of the southwestern United States, the visibility of utility-scale solar energy facilities has been identified as a potential source of negative visual impacts on sensitive visual resource areas.

Torresol Gemasolar Power Tower, Fuentes de Andalucía, Spain
Torresol Gemasolar Power Tower, Fuentes de Andalucía, Spain

Solar Facility Siting Challenges

Land management agencies are increasingly presented with applications for the siting of utility-scale solar facilities. Because there are few large-scale solar energy facilities in operation within the United States, especially of those employing non-photovoltaic (PV) solar technologies, the basic visual characteristics of the facilities are not well understood; however, agencies need to obtain an understanding of these characteristics to better predict associated visual impacts and identify effective strategies for mitigating visual impacts.

Study Summary

Argonne National Laboratory's Environmental Science Division, with support from the U.S. Department of the Interior's National Park Service and Bureau of Land Management, examined the visual characteristics of various PV, power tower, and parabolic trough facilities located in Nevada, California, and Spain. Field-based observations of the facilities were made to assess and document the potential sources of visual contrast associated with each.

Study Results

Observed sources of visual contrast from parabolic trough facilities included glare from heat transfer fluid tubes or related components, geometric patterns of reflected light that created strong scintillations, plumes associated with cooling towers, and reflections from mirror supports and ancillary facilities. In some cases, glare was bright enough to cause strong visual discomfort and temporary after images when observed at distances as far as several miles.

Color Changes on a Parabolic Trough Facility in Nevada, Caused by Reflection of the Sky, Clouds, and Sunlight in the Mirrors of the Solar Collector Array
Color Changes on a Parabolic Trough Facility in Nevada, Caused by Reflection of the
Sky, Clouds, and Sunlight in the Mirrors of the Solar Collector Array.

PV and parabolic trough facilities were found to be easily visible at long distances in both daytime and nighttime observations, as were power tower receivers. Other visual effects observed included dramatic and rapid changes in the apparent colors and/or reflectivity of the solar collector arrays of parabolic trough and thin-film PV facilities, depending on the time of day, viewer location, and viewer movement. Regardless of the solar technology employed, ancillary facilities such as buildings, steam generation facilities, cooling towers, grid connection facilities, fences, roads, lighting, and cleared soil were judged to contribute significantly to observed visual contrasts.

Project fieldwork concluded in 2012. Study photographs and associated data are available through an online database and a Google Earth KMZ file (KMZ, 15KB). Interim and final study results were incorporated into project reports, training courses on visual impact assessments, and a publication.

For More Information

To learn more about EVS visual resource analysis projects, contact: