Real Data on the Solar Eclipse

As the 2024 solar eclipse dimmed the United States on April 8, 2024, every solar installation in its path experienced a dip in production. For me, the most exciting part of the eclipse wasn’t the actual eclipse, but rather watching the energy output on my solar panels dip and then rise, not only EXACTLY when NASA said it would, but even by the exact amount NASA predicted.

On the morning of the eclipse, I checked the NASA Eclipse Explorer for what to expect for my location. It gave me the following:


It would start at 12:51pm, peak at 2:06pm, and end at 3:19pm, and cover at most 87% of the sun. Shortly before totality, I went over to the local hackerspace Sector67, where Chris had a telescope hooked up, some viewing goggles, and welding helmet glass. This was the view from the welding glass; basically a green crescent.

The small green crescent is the sun through the welding glass.
Chris set up a telescope, and the image is projected onto a screen.

While we were there, Air Force One left Madison and flew directly overhead, so we got to see that as well.

It wasn’t until after it got dark that I could collect the coolest graphic out of all of them; the solar panel output.

The small spikes are the occasional wispy cloud going overhead. Typically the graph looks very round, and it never has a beautiful dip like that in the middle of the day. So how did it match NASA’s prediction? For times, I picked the point where output started dropping for the start time, the lowest power output for the peak time, and the highest point where it ended. For % coverage, I first compared the power output value at the peak time against the power output at the start time. It’s clear that power output was already falling in the afternoon once the eclipse was over since it never recovered to the same level as before the eclipse started, so that’s not perfect, and it gave me the overestimate of 90%. It’s hard to pinpoint exactly where the power output WOULD have been at 2:06pm, but we can approximate it to somewhere around 2.4-2.5 on the graph. That gives us an approximate decrease in power output of… 87%.

NASASolar Panels
Start Time12:5112:53
Peak Time2:062:06
End Time3:193:15
% Coverage87%87%

Isn’t that amazing?