This week’s solar eclipse was the first coast-to-coast solar eclipse to travel across the United States since 1918. It lasted a short period of time, taking approximately one hour and 33 minutes to make the journey.
Back in 1918, the U.S. energy grid of course didn’t rely on solar energy. However, that’s changed dramatically. Just the past 16-plus years has seen a massive jump in total solar capacity (distribution and transmission connected) in the U.S., from 5 MW in 2000 to 42,619 MW in 2016.
According to U.S. Energy Information Administration (EIA), the eclipse affected approximately 1,900 utility-scale solar photovoltaic (PV) power plants in the United States. However, the North American Electric Reliability Corp. (NERC) did not anticipate any reliability issues for the bulk power system, as relatively little solar PV capacity was in the “path of totality” (Fig. 1). Yet some utilities did experience a sudden increase in load that was previously being supplied by behind-the-meter photovoltaic generators.
Before the event, system planners and operators began preparation and cooperation to understand how a solar eclipse could affect power flows and resources. A white paper by NERC, titled “A Wide-Area Perspective on the August 21, 2017 Total Solar Eclipse,” identified the potential effects of the eclipse on the amount of solar generation required to serve the forecasted hourly load. It shares results while providing an overview of data collection, assumptions, and test cases.