Solar Panels and the Eclipse

How will the 2017 solar eclipse impact solar energy generated in the United States?

Large- and small-scale owners of photovoltaic (PV) cells alike will see a drop in their generated power during the solar eclipse. Many of these facilities display ongoing monitoring of the energy generated for each day. For example, the graph at right from St. Anthony de Padua Catholic Church in South Bend, IN, depicts the power measured during a partly cloudy day.

I encourage institutions of learning that have installed PV energy to have students predict how the graphs of a normal clear day in August will compare to the graphs of August 21.

During the eclipse, some electric companies will have to increase output from other sources to compensate for the decrease in solar power. The US Dept. of Energy reports:

...The path of totality only affects 17 utility-scale solar PV generators, mostly in eastern Oregon. Hundreds of plants totaling about 4.0 gigawatts (GW) of capacity—mostly in North Carolina and Georgia—will be at least 90% obscured. Another 2.2 GW and 3.9 GW of capacity are in areas that will be at least 80% and at least 70% obscured, respectively.

The values in this analysis reflect utility-scale generators of at least one megawatt of capacity and do not include small-scale solar PV systems or utility-scale solar thermal generators, which in 2016 provided 0.5% and 0.1% of total U.S. electricity generation, respectively, compared with utility-scale solar PV, which provided 0.8%. EIA’s capacity and generation data for small-scale solar PV systems is only available at the state level.

A white paper dubbed Wide-Area Perspective from April 2017 anticipates the August 2017 solar eclipse and its impact on the bulk power system (BPS):

"This Wide-Area Perspective on the August 21, 2017 Total Solar Eclipse document was created in order to evaluate potential reliability consequences of the total solar eclipse on the BPS. This assessment focuses specifically on impacts of system loading and potential reliability implications when an area experiences a large reduction of distributed energy resource (DER) capacity due to a total solar eclipse. Ramping is a specific concern for areas with large amounts of variable generation in their resource mix.

The map shows photovoltaic generator distribution in the US, direct normal solar irradiance, and bands of five percent increments of eclipse obscuration. California and North Carolina are impacted the most during the 2017 event. Source: NERC Wide-Area Perspective

The March 2015 solar eclipse in continental Europe was a stress test on its grid, which experienced "significant deviation in available solar generation." The graph shows the comparison of expected feed-in from solar during clear sky conditions with and without the solar eclipse. Source: ENTSO-E / SolarPower Europe – Solar Eclipse March 2015 Policy Brief

How will your small, independent solar panels fare? Feel free to send me a graph of your normal power output and that from August 21. I'm not sure how (or if) I'll use the information, but I'm curious to see. Thank you.

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