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Sound Byte: DoD Solar Power & the 2017 Total Eclipse
A total solar eclipse darkening the sky (Image courtesy of Adobe Stock)
On Monday, August 21, 2017, a total solar eclipse will darken skies across the continental U.S. (CONUS), throwing a 165-mile-wide strip known as the “path of totality” into near darkness. However, one need not be directly in the path of the moon’s shadow to experience a sharp reduction in sunlight: the bulk of CONUS will be, at minimum, 70 percent darkened at the moment of “maximum obscuration” . Even the northern tip of Maine and Brownsville, Texas, will receive 50 percent less sunlight at their respective heights of the eclipse event.
This reduction in solar radiation energy is set to have a significant effect on an important source of electricity generation for both Department of Defense (DoD) and civilian-managed electrical grids: solar photovoltaic (and thermal) panels. In California, the eclipse will simultaneously reduce solar power generation by an estimated 5,611 megawatts – an amount tantamount to instantaneously powering 6 million homes  – while also boosting net electricity demand as users turn on lighting to compensate for the daytime darkness.
Growth in Solar Power
The last total solar eclipse to hit CONUS came in February 1979, when utility-scale solar power was effectively zero. It has grown rapidly since 2009, and in calendar year 2016, solar represented just under 1 percent of the U.S.’ total generation capacity . Currently, DoD relies on solar panels for electricity at about the same percentage as the nation at large, but it is installing new solar capacity at a fairly rapid clip. In FY 2015, solar represented 15 percent of DoD’s total renewable energy production; that figure rose to 22 percent in FY 2016 . It is likely that both DoD and the wider civilian grid will continue to witness swift increases in solar power in the U.S.; some energy forecasters anticipate that the solar sector will be four times as large in 2025 as it is today [5,6].
In FY 2016 alone, DoD installed 1,361 electricity generation projects on domestic installations that included a component of photovoltaic (PV) and/or thermal solar power . Several of these are located not in the path of totality, but as mentioned above, in regions where a large majority of sunlight – and thus solar power – will be obscured during the eclipse event. For example:
- In February 2016, Fort Detrick installed an array of solar PV panels with a capacity of 15 megawatts. Fort Detrick will experience at minimum 80 percent of sunlight obscured by the eclipse at the time of maximum obscuration.
- Also in 2016, the United States Air Force installed a 19-megawatt solar PV array at Nellis AFB in Nevada. It will experience at minimum 70 percent of sunlight obscured by the eclipse at the time of maximum obscuration.
Much of DoD’s installation energy relies on a combination of electrical power sources. Thus, the chance that another generation source fails simultaneous with an eclipse event is small, but not insignificant. In FY 2016. DoD reported a total of 701 major utility (electric or water) outages at installations that lasted eight hours or longer . DoD should take steps to ensure that adequate backup or standby generation is on hand at installations with significant solar power capacity installed. DoD planners might also prepare for the next total solar eclipse event to hit CONUS – in 2024 – when solar power is likely to be exponentially more important to the national grid than it is in 2017.
Related Content: Tech Talks: DoD Solar Power and the 2017 Solar Eclipse
- U.S. Energy Information Administration. (2017, August 7). Solar eclipse on August 21 will affect photovoltaic generators across the country. Retrieved from https://www.eia.gov/todayinenergy/detail.php?id=32372 (accessed August 17, 2017)
- Nikolewski, B. (2017, May 17). There goes the sun: California’s electric grid prepares for a solar eclipse this summer. San Diego Union-Tribune. Retrieved from http://www.sandiegouniontribune.com/business/energy-green/sd-fi-solar-eclipse-20170508-story.html (accessed August 17, 2017)
- U.S. Energy Information Administration. (2017, July). Monthly Energy Review July 2017, Table 7.2a, Electricity Net Generation: Total (All Sectors). Retrieved from https://www.eia.gov/totalenergy/data/monthly/pdf/sec7_5.pdf (accessed August 17, 2017)
- U.S. Department of Defense, Office of the Assistant Secretary of Defense for Energy, Installations, and Environment. (2017, July). Annual Energy Management and Resilience (AEMR) Report, Fiscal Year 2016. Retrieved from http://www.acq.osd.mil/eie/Downloads/IE/FY%202016%20AEMR.pdf (accessed August 17, 2017)
- U.S. Energy Information Administration. (2017, January 5). Annual Energy Outlook 2017, with projections to 2050. Retrieved from https://www.eia.gov/outlooks/aeo/pdf/0383(2017).pdf (accessed August 17, 2017)
- Energy Innovation Policy & Technology, LLC. (2017). Policy Solutions Model, v1.2.4. Retrieved from https://us.energypolicy.solutions/scenarios/home (accessed August 17, 2017)
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