How to Make a Solar Oven

Do you know how to make a solar oven? I’ve always wanted to try one, so when the UK was unusually hot last summer we gave it a go. It was actually much easier than I expected and our marshmallows melted very quickly.

If you fancy setting up a few garden activities on a sunny day another idea is to create a DIY sundial.

What you need to make a solar oven

Cardboard box – like a pizza box
Aluminium foil
Matte black paper or card
Clingfilm
Food – not raw meat – we used marshmallows
Plate

Labelled diagram of a solar oven for a summer STEM challenge

How to make a solar oven

Cover the inside of the box lid with foil and the bottom with matte black card.

Place your food on a plate in the base of the box

Position the box so it faces the sun, adjusting the lid so the light is reflected onto the food. Fix the lid at this position with tape, a tack or stick.

Cover the food base with clingfilm to keep your food clean.

Solar oven made in a pizza box with marshmallows covered in foil — Marshmallows in a solar oven

After about 30 minutes our marshmallows had melted enough to squish between some biscuits.

S'more made in a solar oven — Melted marshmallow between 2 biscuits

How do Solar Ovens work?

The matte black paper absorbs the heat while solar radiation from the sun is reflected from the aluminium foil onto the food.

We tried a different activity with crayons and left one crayon in the sun on a shiny metal plate and one on a plastic plate. The crayon on the metal plate melted fastest. Why do you think this is?