solar oven backside

First solar oven in Portugal Part II

As the first post was already lengthy, this post will continue where the last one left off and describe two more cooking experiments.

I finally managed to find an IR thermometer. I was looking for a more traditional oven temperature gauge, but this will work nicely to show clear readings.

It’s my last day in Biovilla Sustentabilidade, so I wanted to use the chance to cook some more as it was a sunny and warm day, around 23 degrees.

I propped the oven on the east side of the house to catch the morning sun and at 10, I was able to get a reading of over 100°C.

Macaroni measures

Chair as a solar oven stand
Garden chair repurposed for scientific experimentation
Solar Oven temperature measurement
The highest reading so far, 106.6°C
pasta in solar oven
Macaroni ready to be cooked










I had some whole-wheat macaroni, so I put some water, oil, spices, salt and the pasta in the smaller dish and closed the lid. An hour later the macaroni was softened enough to eat, but I left it for another hour to make it almost mushy. At 12 the thermometer showed 68°C on the pasta and over 80°C on the black dish below.

While munching the macaronis, I left the oven to dry by leaving the fastener hook between the lid to circulate air. This way the oven dries automatically in about 15 minutes.

After closing the lid again properly, I took another reading and got the highest temperature so far, 106.6°C.  This temperature reading is inspiring, as it shows that the oven can handle most cooking jobs on sunny days.

Cooking pasta with solar oven
Cooked macaroni in Solar Oven

Encouraged, I sliced a sweet potato I had, and put it in the oven to cook for the afternoon. Somewhere around 3 o’clock I moved the oven on the backyard.

Finally at 6, I was feeling hungry and open the box to see a pleasing sight of steam rolling up. The sweet potatoes were well-cooked in six hours, but not too soft yet.

So I had my second meal of the day prepared with the rays of sun. You can cook lunch and dinner with the oven if you time them right.

At the same time I realized the limitations with this setup. For example, if I had tried to cook a full dish of lasagne, it would have probably not been cooked well. Once again, using a large roasting bag raises the temperature and allows to cook more faster (if you can find any).


  • The temperature of the cooking dish drops fast when I open the lid, about 1 degree every second. It’s better to keep the lid closed as much as possible when cooking.
  • Smooth mirror would raise the temperature more, as the rugged surface diffuses the rays too much in this one
  • It’s good idea to keep a damp rag at hand to clean the glass which collects dust and pollen quite fast
  • Some sort of weather-proofing is a good idea

For the next oven of this type, I will be more precise with the woodwork and add more insulating material (+5cm) on the sides and bottom evenly. With these improvements and a smoother mirror, I’m confident to reach temperatures of 150°C.

solar oven backside
The wooden oven sits well in the surroundings
Sweet potatoes in solar oven
Some sliced sweet potatoes
cooked sweet potato slice
Yummy sweet potato










Also, Thanks for everyone in Biovilla. The place was amazing and the people were warm, generous and very friendly throughout my stay. I’m sure I will be back soon.

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