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Another Way to View the August 2017 Solar Eclipse

Another Way to View the August 2017 Solar Eclipse

On Monday, August 21, 2017 millions of people across the United States donned special glasses and headed outside to watch the Moon pass in front of the Sun. If you didn’t make it outside yourself, you probably saw fantastic photos of the eclipse on the internet or television. Depending on your location in the US, the sky may have darkened significantly. Consider a different aspect of the Solar Eclipse: its effect on solar power generation. For this observation, you won’t need special glasses.

What does solar array power generation look like throughout the course of a day? At a site in Massachusetts, a perfectly sunny day in August is a smooth bell-shaped curve.

Solar generation on a sunny summer day.

Solar generation on a sunny summer day.

 

On a partly cloudy day in August, at the same site, the curve is the same general shape, with many small dips in power generation, as clouds pass between the sun and the solar array.

Solar Generation on a Partly Cloudy Summer Day

Solar generation on a partly cloudy summer day.

On August 21, 2017, the day of the Solar Eclipse, note the significant decrease in power generation from 2:00 – 4:00 pm.

August 2017 Solar Eclipse

August 2017 Solar Eclipse

In this area of Massachusetts, at the height of the eclipse (at 2:46 pm), the sun was approximately 67% covered. On a sunny clear day we would expect 255 kw to be generated on these panels at 2:46 pm and on the day of the eclipse only 80 kw were generated at the height of the eclipse…. 68% less than what would be expected had the eclipse not occurred. The image below overlays the solar eclipse on the sunny day to easily display the difference in solar generation during the period of the eclipse.

Solar eclipse compared to a sunny summer day.

Solar eclipse compared to a sunny summer day.

What observations did you make during the solar eclipse?

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