Solar Thermal Cookers: [An Essential Guide]

Solar thermal cookers are a simple, efficient, and environmentally friendly way to cook food using the sun’s energy.

In this post, we've gathered all the information you need to know about these eco-friendly devices. We'll teach you what they are, how they work, the different types that are available, and some of the pros and cons of using solar thermal cookers.

What are Solar Thermal Cookers?

Solar thermal cookers are devices that use the sun’s energy to heat up materials inside the cooker.

The heat from the materials is then used for cooking food. Solar thermal cookers come in various shapes and sizes and can be used to cook a variety of different foods.

Solar thermal cookers are a great way to cook your food without using electricity or traditional fuels.

Components of a Solar Thermal Cooker

The components of a solar thermal cooker vary depending on the design. However, the basic solar thermal cooker consists of a box with a transparent lid, which allows sunlight to enter.

The lid is covered with a reflective material, which directs the sunlight to the bottom of the box.

The reflector can be made from various materials, including metal, plastic, or glass.

There is a dark spot or container inside the box, which absorbs the heat from the sunlight and cooks the food.

The Basic Working Principles of Solar Thermal Cookers

Solar thermal cookers work by utilizing the simple principles of reflection, concentration, and absorption.

Reflection

Solar thermal cookers use reflector(s) to focus sunlight onto a small area, which then heats up a cooking vessel.

Concentration

Sunlight is concentrated onto a dark surface, which then absorbs the heat and cooks the food.

Absorption

A black pot or pan absorbs the concentrated heat from the sun and then uses that heat to cook food.

Solar Thermal Cooker Designs

There’re three main categories of solar thermal cookers depending on the shape, the number of reflectors used, and the mechanism for moving the reflectors.

1. Shape

Parabolic solar thermal cookers

A parabolic solar cooker is a type of solar cooker that uses a curved reflector to focus sunlight onto a pot or container.

The advantage of a parabolic solar cooker is that it can achieve higher temperatures than other types of solar cookers. This makes it suitable for cooking foods that require a high temperature, such as meat and poultry.

Box solar thermal cookers

The most common type of solar thermal cooker is the box cooker. This design is simple, inexpensive, and easy to build. The box cooker consists of an insulated box with a glass top. The pot of food is placed inside the box, and the sun’s rays are focused on the pot to heat it up.

2. Number of reflectors

Single reflector solar thermal cookers

Single reflector solar thermal cookers use a simple reflector made of metal or cardboard, which focuses the sun's rays on a pot or container of food. The reflector is attached to a stand or frame, which allows it to be angled towards the sun.

Multiple reflector solar thermal cookers

A multiple reflector solar thermal cooker is a type of solar cooker that uses a number of mirrors to reflect sunlight onto a cooking pot. This increases the heating rate, allowing food to be cooked in as little as 30 minutes.

The design of a multiple reflector solar thermal cooker consists of a cooking pot, several mirrors, and a frame to hold the mirrors in place.

The mirrors are arranged around the cooking pot so that they all reflect sunlight onto the pot. This increases the amount of sunlight absorbed by the pot, which speeds up the cooking process.

3. Mechanism of moving the reflectors

Solar thermal reflectors with automatic reflectors

Solar thermal cookers with automatic reflectors are a new technology that can increase the efficiency of solar energy cooking. The best part of this technology is that the reflectors can automatically adjust to follow the sun.

This means that the receiver can always be in direct sunlight, which increases the cooker's efficiency.

Solar thermal cookers with manual reflectors

A manual reflector is an angled piece of metal or plastic used to reflect sunlight onto the pot or pan. The angle of the reflector can be manually changed to adjust the amount of sunlight that is concentrated on the pot.

These types of solar thermal cookers have the disadvantage of being inefficient.

A new design for solar thermal cookers: Evacuated solar thermal cookers

An evacuated solar thermal cooker is a new type of solar cooker that uses an evacuated glass tube to collect and concentrate solar energy.

This type of solar cooker is more expensive to make than other types. But the advantage is that it can achieve much higher temperatures and can be used to cook almost anything.

The evacuated solar thermal is the most expensive but the most efficient.

DIY Solar Thermal Cooker

Many models of solar thermal cookers can be made from materials that you already have lying around your home. The easiest to make is the box solar thermal cooker.

To make a box solar thermal cooker, you will need:

A cardboard box
An oven bag or large piece of plastic wrap
Aluminum foil
Metal rods
Scissors
Tape
A pot or pan

Here’s the procedure to follow:

Cut the top off the cardboard box and set it aside.
Cut a piece of oven bag or plastic wrap that is large enough to cover the bottom of the box. Tape it in place.
Cover each square of the top surfaces of the cardboard with Aluminum foil (reflective material).
Support the top surfaces with the metal rods (45 degrees) so that the reflective material faces the sun.
Put your pot or pan inside the cooker and leave it in full sun.
Wait for your food to cook.

Qualities of a Good Solar Thermal Cooker

A good solar thermal cooker should have the following qualities:

Affordability

Solar thermal cooker price depends on various factors, such as the design. However, most are cheap to make, therefore should not cost much. A good standard solar thermal cooker should cost around $200.

Durability

Durability is an important factor to consider when choosing a solar thermal cooker. The cooker should be able to withstand outdoor conditions, including wind, rain, and snow. a good solar thermal cooker should last for at least 10 years.

Heat absorption and retention

A good solar thermal heater should absorb as much sunlight as possible and be able to retain the heat it absorbs so that the food can cook slowly and evenly.

Good size and shape

Solar thermal cookers come in various shapes and sizes, so there's sure to be one that fits your needs.

Lightweight

When it comes to the size of solar thermal cookers, you should choose the small ones if you are for portability or the large and stationary ones if you want a cooker that can accommodate multiple pots.

If you need to carry your solar thermal cooker with you on trips, it's important to choose one that’s lightweight. You don't want to be struggling to carry a heavy and bulky cooker around with you.

Angle of the reflectors

The angle of the reflector surfaces is also important when choosing a solar thermal cooker. It should be adjustable to change the angle to face the sun as it moves across the sky. This will help you get the most heat from the sun.

Applications of Solar Thermal Cookers

Cooking food

Solar thermal cookers can be used to cook a wide variety of food items. They are especially good for dishes that require a long cooking time, such as stews and curries.

Solar thermal cookers can also be used to bake bread, cakes, and pies.

Water pasteurization

Solar thermal cookers are a great way to pasteurize water. They use the sun’s heat to slowly cook water, killing any harmful bacteria. This is an excellent way to ensure your water is safe to drink, especially when you’re camping or traveling.

Drying fruits and vegetables

Solar thermal cookers are a great way to dry fruits and vegetables. There are two things to keep in mind, though, when using a solar thermal cooker to dry food:

Make sure the food is spread out evenly in the cooker. This will help it dry evenly and prevent burning.
Keep the lid on the cooker as much as possible. The more heat that stays in, the faster the food will dry.

Pros and Cons of Solar Thermal cookers

Solar thermal cookers have some advantages and disadvantages over other types of cookers.

Pros

Common designs are very cheap to build
They are powered by the sun, which is a renewable resource
Eco-friendlier and don’t produce any emissions like traditional stoves and ovens
Solar thermal cookers are cheaper to operate and maintain
They also last longer since there is no heating element that can burn out or be damaged
Solar thermal cookers are safer than traditional cookers. This is because they don’t produce any flames or heat.

Cons

Solar thermal cookers are only suitable for simple cooking
Dependent on the sun for cooking so can only be used during daytime
Low efficiency, especially during cold weather
Can cause eye damage
Take longer to cook food than traditional methods
There may be inconsistencies in cooking
Health problems related to improper sanitization of food and water contamination.

Which solar thermal cooker is the best?

The best solar thermal cooker is the one that suits your needs perfectly. The best way to find the right solar thermal cooker for you is to think about how you’ll use it.

If you’ll be using it mainly to cook food, you’ll want a large enough model to hold a pot or pan. Other factors to consider include:

The type of food you want to cook
The climate where you live
How much money do you want to spend?

Are solar thermal cookers a good alternative to conventional cookers?

Solar thermal cookers are a good alternative to conventional cookers for several reasons:

They are cheaper to operate than electric or gas cookers
They also use a fraction of the energy that traditional cookers use
They don't release emissions hence are more environmentally friendly
They are easy to use and can be set up in just a few minutes
They are portable so that you can take them with you on camping trips or picnics

Is a solar thermal cooker the same as a solar oven?

Solar thermal cookers and solar ovens are designed to use the sun’s energy to cook food. However, there are some key differences between the two.

A solar thermal cooker uses a reflector to direct sunlight onto a pot, which then heats the pot and the food inside of it. On the other hand, a solar oven doesn’t use a reflector; it simply traps heat in an insulated box to cook the food.

How long do solar thermal cookers last?

The lifespan of a solar thermal cooker depends on a number of factors, including the quality of the cooker, how often it is used, and the climate conditions in which it is used. Most solar thermal cookers last for around 10 years but can last up to 20 years.

Why will a solar thermal cooker fail?

A solar thermal cooker won’t work as intended if it’s not aimed at the sun correctly. If the cooker isn’t pointed directly at the sun, the rays won’t be concentrated enough to heat the food inside.

Another reason a solar thermal cooker may not work is that the reflectors are dirty or covered in snow.

If the reflectors are not clean and shiny, they’ll not properly reflect the sun's rays. And finally, if it’s a cloudy day, the solar thermal cooker won’t work because there isn’t enough sunlight to heat the food.

Signs of a failing solar thermal cooker include:

Insufficient heat production
Uneven heat distribution
The food is taking too long to cook

Are solar thermal cookers worth it?

There are a lot of solar thermal cookers on the market. Some are good; some are not so good. So, are solar thermal cookers worth it?

The answer to that question depends on two main factors. One is the cost of the solar thermal cooker.

They vary in price, but most are not expensive. The other factor is how much sun you get where you live. If you have a lot of suns, a solar thermal cooker is definitely worth it.

What is the biggest disadvantage of solar thermal cookers?

The biggest disadvantage of solar thermal cookers is that they can’t function or be of any use without sunlight. If it's cloudy or raining, there is no way to cook food using this method.

Additionally, if you want to use a solar thermal cooker to pasteurize water, you also need direct sunlight.

Wrapping Up

Solar cookers take a bit longer to cook food, but they’re very easy to run and don't require any fuel, so they’re perfect for people who don’t have easy access to traditional cooking fuels.

They are also very eco-friendly and can save you a lot of money in the long run. Get or make your solar thermal cooker and start cooking with free solar power today!