Solar Cooking Science: Melting Marshmallows

We had a bit of fun on Friday afternoon, melting marshmallows to make s’mores, using the Thames & Kosmos Solar Cooking Science kit.

After a week of higher than 100 degree Fahrenheit heat, the weather finally cooled down to a high of 80 degrees on Friday…. cool enough for us to head outside for a solar energy experiment.

  1. First, we built the solar oven provided in the Solar Cooking Science kit.
  2. We put the oven out in the sun to warm up.  It was 1:30 in the afternoon, between the recommended hours of 11:00am and 3:00pm.  We oriented the solar cooker towards the sun.  The temperature outside at the time of the experiment was 77 degrees Fahrenheit.
  3. I put a bit of hazelnut spread (we used Loacker’s, but any will do… Nutella, etc), on half of a graham cracker and set the marshmallow on top.
  4. We put the graham cracker and marshmallow into the solar cooker.  And waited!

Solar Cooker S'Mores 007

Solar Cooker S'Mores 011

Result:  It took 10 minutes for the marshmallow to melt.

Then we made a s’more, ….

Solar Cooker S'Mores 014-001

…which my son thoroughly enjoyed eating.

Solar Cooker S'Mores 018

The Solar Cooking Science kit includes information about solar cooking science theory, concentration of light rays using a magnifying glass and with a parabolic mirror (like we built in the kit), how solar cooking is used in the real world, and instructions for some solar cooking experiments.  The marshmallow experiment was not included in the kit, but they do recommend trying to cook the following items in the solar cooker…

  • Boiled water for tea
  • Toasted bread
  • Heated soup
  • Baked potato
  • Roasted nuts
  • Hard boiled egg

What a fun way to learn about cooking using the sun’s renewable energy!

For more information about the science kit, check out the kit on the Thames and Cosmos webpage… Solar Cooking Science.

Oh, by the way, I purchased this kit for our own use at the Lawrence Hall of Science.  I was not compensated in any way for using and writing about this science kit.

Interested in s’mores or in making your own solar cooker out of a pizza box?  You may enjoy these articles…


  1. What fun! Lovely, yummy photos:-)


    1. They were quite tasty!


  2. LB says:

    Awesome! Love a s’more! and that photo of your child with sunglasses is great! Mostly, I love to read all that he is learning from you and your commitment to the earth!


    1. I was concerned about the sunlight reflecting out of the cooker! I asked him to not look directly into it, but had him wear sunglasses, too, just in case. 🙂


  3. rumpydog says:

    Once I heard a story on NPR about an NGO that was distributing kits like these to women in….. I believe it was Afghanistan? It eliminated the need to use fire as that was their sole source of energy to cook with.


    1. Yes, I read this somewhere, too. It’s an inexpensive way to cook using free, renewable energy.


  4. Thanks for including the link to the cooker. Will have to give that!one a go. We’ve dabbled in solar cooking while living in Florida and hurricanes would take the power out for long periods. This looks pretty handy and your s’mores looked terrif!


    1. Yes, I thought this would be a fun item to take camping places where campfires aren’t allowed (common out here in California where campfires are a serious hazard).


  5. Tracy Dodge says:

    Cool! Looks like fun. How hot does the solar cooker get inside?


    1. I’m not sure exactly how hot it gets, but hot enough to boil water!


  6. Alex Jones says:

    Good idea.


    1. The cooker worked pretty well!


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