How to Make a Solar Cooker Easily at Home

Climate change and global warming have been like a nightmare in most nations of the world for the past couple of years.

As a result, human beings have been seeking better ways to show kindness to their environment since a good environment means a better dwelling place for humans.

One of the ways through which human beings are turning away from hurting the environment is by seeking better alternatives to conventional energy sources. For example, more people are preferring to use a solar cooker over a charcoal cooker.

So, today we shall go back to history to see the solar cooker ideas passed on to us and how to make a solar cooker easily at home. But first things first, let's start with the basics!

What is a Solar Cooker?

Most people use the terms "solar cooker" and "solar oven" interchangeably, but both mean the same thing. But what exactly are these vessels?

A solar cooker/oven refers to a cooking vessel that takes sun rays, converts the rays into heat, and then uses the heat to cook food.

Some of the parts you will find in a solar oven include a reflector, polished metal or cardboard, and aluminum foil, among others depending on the cooker model.

A simple DIY solar oven can give you a 300°F which is the perfect temperature to bake most foods.

Some innovators have even broken records by creating solar cookers that offer beyond 500°F temperatures. You can comfortably sear some meat or fry other foods without using charcoal or electricity at this temperature.

Types of Solar Cookers

There are four main types of solar ovens: box cookers, panel cookers, vacuum tube cookers, and panel cookers. Let's now see each of these models in detail.

Box solar cookers

A box solar cooker features an insulated box, a glass top, and reflectors to guide sunlight energy into the oven.

A simple box solar cooker can help save around 16.8 million tons of firewood and prevent about 38.4 million tons of carbon dioxide emissions annually. 

However, box solar cookers are the least efficient but easy to construct compared to other solar cookers. We shall see how to make a box solar cooker later in this article.

Solar panel cookers

This cooker features several reflectors. Also, this oven has a place in the middle for placing your cooking pot. 

One vital strength to note about this sun oven is that it is more efficient than the solar box we have just spoken about above.

However, one drawback with this simple solar cooker is that it can quickly lose heat during a windy day. 

Vacuum tube cookers

This solar cooker is the latest model in the market today. A vacuum tube solar cooking vessel features some parabolic reflectors and a glass cooking tube in the middle.

The glass on this cooker resembles the double-wall insulation on your travel mug and helps in trapping heat.

Parabolic solar cookers

A parabolic solar cooker has a curved shape to capture sunlight efficiently. Also, this cooker resembles a radar dish; you would think the two are siblings!

Something else to note about these parabolic solar ovens is that they are expensive to manufacture. The high manufacturing costs result from the nature of their construction and superior ability to track the sun.

Advantages of a Solar Cooker

● A solar cooker helps you save on fuel bills since sunlight is free

● It doesn't pollute the environment

● You can sanitize water using a solar cooker

● It's less likely to burn or dehydrate food when cooking in a solar cooker; thus, the quality of your food remains intact

● Low maintenance efforts needed

● There is a solar cooker model for every budget

Disadvantages of a Solar Cooker

● Solar ovens take longer to attain the desired cooking temperature, and as a result, the cooking process might take long

● It might be challenging to use a solar cooker during a cloudy, windy, rainy or snowy day especially if it doesn't have a thermal storage system

● You will need to keep unprotected eyes from the reflected light 

● You can't fry or roast a lot of food at a go on a solar cooker as you do on an offset smoker grill

Historic Solar Cookers

Before I take you through the simple steps of making your solar cooker, let's first see the origins of this concept. 

This way, you will be able to relate to the journey of this innovation. Also, you will be free to analyze the recommendations given here and probably come up with an award-winning solar cooker!

If there is no other concern, let's now see several historic solar ovens.

SPRERI type concentrating solar cooker

This SPRERI solar cooker, as seen in the below diagram, was developed in 2003 by Sonune in conjunction with other contributors.

Image Source: Google Scholar

The authors of this domestic solar cooker tested it, as seen below.

As you can see in the table above, the SPRERI cooker had a cooking potential, but there was a lot of modification needed to lower the cooking duration. 

High concentration ratio solar box cooker

This solar box cooker had several reflectors and a cooking chamber, as seen below.

Image Source: Google Scholar

The developers of this cooker then tested it using some water and peanut oil, whereby results showed that this solar cooker could boil 1 liter of water for 11 minutes. Also, it would take 41 minutes to heat one 1liter of peanut oil from 40°C to 220°C.

However, the developer of this cooker raised concerns over its high cost of construction and limitations whereby you could only use it on clear sunny days.

That said, the author suggested using a thermal energy storage unit along with this cooker to improve its performance.

Single family solar cooker (SFSC)

Image Source: Google Scholar

SFSC used poly-methyl methacrylate as a glazing material and hardboard for the external casing. The insulating materials of this solar cooker were newspapers, polystyrene, and cardboard. 

After testing this cooker, results showed that it could reach a maximum temperature of 144°C. However, a single-family meal would take over two hours to reach doneness on this cooker.

Transparent Insulation Material (TIM) solar cooker

Image Source: Google Scholar

This cooker featured a double reflector. The materials used to produce this oven resulted in its higher efficiency. 

In addition, the payback period and yearly energy saving were estimated at 1.66 – 4.23 years and 1485 MJ, respectively.

The authors of this cooker carried out a study to identify critical areas in its build that would require improvement. This study recommended improvement in the cooker's heat capacity and optical efficiency. 

Reduced pyramid solar cooker

Image Source: Google Scholar

Kumal and other contributors invented this pyramid-styled solar cooker.

The cooker featured an absorbing plate made of black tinted aluminum with a 49cm air gap. 

In addition, this cooker could achieve a maximum temperature of 140°C with an average temperature of 130°C.

Parabolic Solar Cooker (PSC) with two-axis tracking

This solar cooker was invented and tested by Al-sound and other contributors. The authors of this cooker realized that it could heat water up to 90°C while the ambient temperatures were at 36°C.

The Programmable Logic Controller (PLC) controlled the operations of this cooker. This logic would help cook food or keep it warm.

Another notable feature of this solar cooker was its double-layered wall. This wall's interior featured an aluminum sheet with two glazing surfaces.

Image Source: Google Scholar

Box solar cooker with a rear window

Image Source: Google Scholar

The cooker in figure (a) above was fabricated and tested by Mirdha and other contributors. These authors aimed to have a solar oven that could reach and maintain high temperatures.

Later, the contributors investigated a better way to use the cooker, as seen in figure (b) above. Here, they loaded the oven with two vessels to test it. 

The investigation results showed that the cooker performed better when placed on the lungs since there was more surface area for heat transfer. 

This concept later birthed the cylindrical-shaped cooker in figure (c) above. The cylindrical solar oven became more efficient and affordable for a rural population.

Box solar cooker without reflectors

Image Source: Google Scholar

Guidara and other contributors developed this solar cooker. These developers created a mathematical model and used it to examine the temperatures of the different parts of the oven.

The test results showed that temperatures increased significantly on the absorber plate when the reflectors were in use compared to when the reflectors were unavailable.

Also, the authors discovered that the boiling time of a liquid was directly proportional to the amount of the liquid.

Angular optimization solar cooker

Image Source: Google Scholar

Arabacigil and other contributors invented this cooker and investigated it for more possible features. 

This cooker comprised inner and outer reflectors, with the outer reflectors sitting at 30°. Also, the oven featured some paraffin wax for energy storage.

Solar cooker with an adjustable parabolic mirror 

This solar cooker was invented and enhanced by Zamani and other contributors. Investigations showed that this cooker was more efficient than other models. 

In addition, there were two cooker designs for this model: A Solar Box Cooker (SBC) with a single booster mirror and a Square Parabolic Dish Solar Concentrator Cooker (SPD-SCC).

The authors later investigated the two designs to see which design provided better results.

(a) SBC                                  (b) SPD-SCC

Image Source: Google Scholar

Investigations revealed that both solar cooker designs performed better with matt back coating. However, design improvement on SPD-SCC produced more significant results than design improvement in SBC.

Solar stove with sunlight funnel

Image Source: Google Scholar

The construction of this cooker featured a funnel to concentrate and guide solar energy. In addition, a curved parabolic surface was merged with the funnel and a flat mirror.

Then, the concentrated solar energy on the funnel moved to a stove equipped with a heat exchanger and a storage system.

In addition, the authors investigated two different reflective surfaces to see which best suited this solar cooker. The findings indicated that a more reflective surface produced higher temperatures than a lesser reflective surface.

Also, a temperature of 250°C was attainable with a highly reflective surface.

Recommendations From Historic Solar Cooker Innovators

From all the above historic solar cooker models, many literature works concluded that:

1. Using booster mirrors and reflectors is the most beneficial modification for a box-type solar cooker.

2. Increasing the concentration ratio and improving the construction of solar collection units will lead to higher cooking temperatures and lesser cooking time.

3. A solar cooker that can maintain a cooking temperature of at least 100°C for a long time can cook a significant quantity of meals.

4. Modifying the shape of the absorption plate resulted in higher cooking temperatures and efficiency.

5. An optimum air gap and a Transparent Insulation Material (TIM) improve energy usage and reduce thermal losses.

How to Make a Solar Cooker

Here are the simple steps to follow when making your box solar oven.

1. Tools 

Gather the following tools for the task ahead:

● Cardboard or carton

● Foamboard

● Glass board

● Aluminum foil

● Black construction paper 

● Wire

● A cutter or scissors

2. Prepare the outer box

We will create a box measuring 235mm x 235mm x 140mm in this project. 

3. Insulate the inner box

It's now time to insulate the inner parts of the box. Insulation helps preserve solar energy in the cooker.

So, cut the foam board into four pieces, each measuring 200mm x 110mm x 10mm, then fit them into the interior of the cardboard box.

On top of the base foam board, fit the black plastic wrap using duct tape.

4. Set up the solar reflectors

Solar reflectors are some of the critical features of a solar oven. In our case, we shall use aluminum foil due to its reflection capabilities.

So, begin by cutting the aluminum foil into sizeable pieces that will fit each cooker wall.

Next, glue the aluminum foil pieces on the four walls of the cooker.

5. Fix the glass cover

This cover will act as a door to help you load your food into the cooker or remove the food when done.

Also, the glass cover helps to keep heat in the cooker for a perfect cooking session.

So, ensure you have a level cardboard box top, then fix the glass board.

6. Make a collector

Since we would like to collect a significant amount of solar energy, it will be great to enhance the surface area of the cooker by attaching some collectors to it.

The collector will help collect more heat for a faster cook, especially when there isn't enough sun.

So, to create the collector, grab a carton and cut it into four 470mm x 350mm dimensions. 

Next, fit the aluminum foil pieces on the collectors. Then fit the collectors on top of each wall to look like wings.

7. Test your DIY solar oven

Before placing your expensive foods in there, test your oven first.

So, grab a glass of water and place it in the solar oven. Leave the cooker outside in the direct sunlight.

At around ten to thirty minutes, the water should be hot enough for that cup of coffee.

DIY Solar Oven Tips

Cooking in a solar oven is fun, whether camping or relaxing with your family. So, hereunder are some tips to ensure you have a smooth cooking experience on your solar cooker.

Allow the solar cooker to face the sun

Always ensure that your solar oven is facing the sun. Therefore, you will need to monitor the sun's movements and direct your cooker accordingly.

A solar cooker sitting directly under sun radiations will cook faster than a cooker facing elsewhere.

Use a weather app

Imagine camping somewhere in the wild, and the only cooking vessel you have is a solar cooker. What if it rains the whole day?

To avoid such frustration, you can use a weather app. This way, you can tell beforehand if the weather will be conducive to cook using a solar oven.

Set a timer

You can set a timer to help you not forget that you have a meal cooking outside. The timer will remind you to check the food for doneness.

Use the right cookware

Not every cooking pot is suitable to use in a solar cooker. Skillets and black pans are the perfect cookware for solar cookers. You can even paint your cookware with the same paint used in barbecue grills.

Also, solar cookers accept various cookware materials such as glass, metal, and cast iron.

Keep your cooking pot covered

Have a matching lid for your pot to keep heat inside but resist the temptation to keep opening the lid to stir your food. Frequent opening of the pot will lead to heat losses which might take longer to restore, thus prolonging your cooking time.

Keep reflective surfaces clean 

Reflective surfaces are critical in solar cookers. Thus, you will need to keep these reflectors clean for maximum heat collection and quicker cooking sessions.

Preheat the solar oven

You will need to preheat your solar oven just like you preheat your kamado grill or vision grills. 

So, preheat your solar oven for an hour or two. As a result, your food will start cooking immediately after placing it in the cooker.

Final Word

In this article, we have looked at the foundations laid by several solar cooker pioneers. Based on these amazing innovations, I have provided you with detailed steps on how to make a solar cooker easily at home.

So, grab the tools we have spoken about above and manufacture your solar cooker! This way, you will be saving on fuel bills, conserving the environment, and even opening up your mind to more creative ideas.

References 

1. Advances in the developments of solar cooker for sustainable development: A comprehensive review

2. A comprehensive review on solar cooker tracking techniques for performance enhancement

3. Performance investigation of improved box-type solar cooker with sensible thermal energy storage

4. Safe Minimum Internal Temperature Chart

5. Parabola