Safety first
Remember not to touch hot surfaces because you can burn yourself, and protect your eyes with strong UV protected sunglasses.
Depending on the age range:
- Level 1 - You can experiment with simple processes, such as melting chocolate on cookies, melting cheese on a piece of bread, or heating drinks (a cup of tea, coffee, milk, etc.). Under the guidance of adults or youth, young kids can also prepare a more elaborated dish.
- Level 2 – Prepare and cook a small dish, a slightly more complex meal, not only heating or melting, as in level 1. Prepare the complete menu, add different elements, such as the drinks, garnish and main dish, in at least a portion for one person.
- Level 3 - Like level 2, carry out more complex elaboration processes and prepare portions for a small group; they can be family members, a scout unit , a school work team, etc. As a recommendation: You can join and work as a team to be able to have more than one solar oven or cooker working at the same time. Another option is that several teams prepare in their solar cooker one dish each for the joint menu.
In all cases, you must consider that in general, the processes are slow and therefore, you must plan your dishes and the timing well. On the other hand, you have the advantage that you can do other things while your cooker or oven is working.
Open the cooker and cooking pots the least times possible, as opening means loosing heat and extending cooking time. Using slow cookers (solar oven or panel cooker), there is little need to check and stir – the heating process is slow and the heat well distributed. Food does hardly stick or burn.
Cooking time depends on many factors, like the strength of the sunshine (strong sun = fast cooking), the power of your cooker (defined by its area and light concentration), the amount of food (start with small quantities), the quality and colour (dark or black = best) of your cooking pot and the size of the food to be cooked (chop vegetables in small cubes for fast cooking). Even if solar cooking is very easy to learn, it probably needs some experimenting until you feel confident.
Do not use your solar cooker if the sunlight is too dim or if it is a cloudy day, as you would end up frustrated
Some more cooking tips:
- Start early (clouds might show up, the sun might be less strong than you think, etc.)
- Don't overload, cook using little water first (you can add it later)
- No need to boil potatoes and vegetables in a lot of water (one inch of water is enough to keep them moist)
- Slow cookers are very 'tolerant' (just add all ingredients at once, don't worry much about cooking time)
- Always use a lid (example: boiling water takes twice as long without!)
- Orient your cooker ‘facing the sun’ in the beginning and correct its position every 20 to 30 minutes.
Evaluation
When your meal is ready, you can consume it and eventually share it with others.
THEORY
Not all energy is electricity, and solar energy is not limited to photovoltaics; there are many ways to take advantage of renewable energy for our benefit and without causing damage to the environment. Solar cookers apply different principles to harvest the sun’s energy. Two of them are the greenhouse effect (used in solar box cookers) and the concentration of sun rays at a focal point by using mirrors (for example in parabolic or panel-type cookers).
Remember that solar cooking is normally slow (unless you use a strong parabolic reflector), it will take some time to cook. On the other hand, simmering food is known to preserve some nutritional properties better than other cooking methods.
Fun facts
Did you know that a ‘soft boiled egg’ (i.e. an egg with a liquid yolk and a solid egg white) turns out completely different in a slow cooker than if you boil it in water? And why that is so?
You probably know that boiling eggs in water for 3 minutes leads to the described state of a ‘soft boiled egg’. Cooking an egg in hot air (the situation in a slow cooker where we put the eggs without water) for about 20 minutes leads to the opposite state: the yolk is solid and the egg white still partly liquid.
The reason is that egg yolk solidifies at a lower temperature than egg white. If we add an egg to boiling water, heat transport (kinetics) plays an important rule: A lot of heat enters in a short time into the egg and within the 3 minutes it takes to transport the heat to the yolk, the egg white is already solid! If we place an egg into hot air, the heat enters far more slowly and both the white’s and the yolk’s temperature raise in a slow and comparable way - their temperature stay about equal one to the other. The result is that the yolk solidifies first!
Reflection questions
- Why does a cooking pot that is black outside work much faster than one of a brighter colour when used in a solar cooker?
- Why do we reach a higher temperature with a parabolic solar cooker with a panel cooker? But, on the other hand, what is a big advantage of a panel cooker compared to most parabolic cookers (regarding transportability etc.)?
- Under the same weather conditions, does a solar cooker work faster in the mountains than on sea level? Why? Why not?
Additional activities and advice
- Practice will give you experience, try cooking different meals. Why not make a solar cooker recipe book with approximate times and portion sizes? You could share your knowledge and thus help more people! Remember that solar cooking is not limited to scouting, you can use it in any circumstance, including a family picnic at your school.
- Use good sunglasses and apply all measures of sun protection, as you will spend a lot of time outside in the sun.
- You could also organize a solar cooking competition. The participating teams cook a meal of their choice in their cooker and a jury is testing and rating it at the end. In one version, the organizers set up a table with different food products, the groups can help themselves at this table and improvise a dish for the competition.
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