solar students

Students in Mick Womersley‘s Energy and Energy Efficiency class take advantage of some winter sun to use the historic Jimmy Carter solar panels in their lab.  Note Thomashow Learning Lab pellet boiler silo in background.

If you were in this class, please comment to fill readers in on what exactly you were observing, studying, or testing in these images.

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3 Responses

  1. We were testing the efficiency of some vintage solar thermal panels that were on the White House when Jimmy Carter was running the show. To do this we filled the tubes in the panel with water, let it heat up for 10 min, measured the change in water temperature, and then converted this into kilowatt hours per day per meter squared. We compared this with the kilowatts of energy that the sun beats down on Maine this time of year. My team found that our solar panel had 24% efficiency, which means it was able to make use of a quarter of the sun’s energy. Modern solar thermal technology can get upwards to 70% efficiency.

  2. Couldn’t have said it better myself. The only thing I would add is that we would have had a better-designed test had we used a pyranometer to actually measure the kilowatt-hours per square meter of sunshine hitting the panels. All we had was the average kilowatt hours per square meter per day for this time of year. Yesterday’s sky, although clear, still had a little haze which would have likely reduced the amount of energy hitting each panel compared to the average. Twenty-four percent, the efficiency number Sarah’s team came up with, seems less disappointing in those circumstances.

    In other words, there’s life in the old panels yet!

    Mick

  3. An update: After re-reading what I wrote several weeks ago, I ordered us a pyranometer, and students have now fitted it to our wind turbine test tower, where there’s an appropriate logger. Doesn’t work yet — we had to call the company back to find out why, but they’re a good company and so I’m confident we will get it working. So, next time we teach this class, we’ll have the proper comparison number.

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