A solar cooker is a device that harnesses direct sunlight to cook, bake, and fry foodstuffs. There are many different design styles for the solar cooker, but they all feature in common using no fossil fuels and only solar energy to make food. 

The solar cooker was long considered too slow and impractical to cook food within any reasonable length of time; it was consigned to middle school science fairs and third-world disaster relief. But recent advances in materials technology have drastically reduced the time it takes to prepare food with a solar cooker, making it a serious competitor to conventional ovens.

This post features the following information about the solar cooker:

• A description of how it works 
• Overview of the different types solar cookers (box, panel, parabolic, vacuum tube)
• Analysis of parabolic/vacuum tube hybrid technology
• Tips for how to use a solar cooker effectively
• Where to buy a solar cooker

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How Does a Solar Cooker Work?

One of our ultimate goals is to demonstrate and train how solar cooking technology works and how this type of technology can better the lives of families everywhere. Understanding the various physical science helps new solar chefs understand what it takes to harness the power of the sun, and create some serious cooking power to create some.

Reflection & Ray Tracing

To generate functional cooking temperatures from the sun, you are going to need to gather or concentrate a lot of sun. Using mirrors and other reflective surfaces, we can move the sun’s rays around and increase their intensity onto a specific surface. By using aluminum foil, Mylar, or mirrors, solar ovens basically multiply the amount of sun on a cooking chamber to boost its efficiency.    

 

 

Ray Tracing is a “method of calculating the path of waves or particles through a system of regions by varying propagation velocity, absorption characteristics, and reflecting surfaces.” Many conditions and surfaces complicate the analysis because waves and rays tend to bend, refract, and reflect off surfaces. Good, everyday examples of the complexity of ray tracing are radio, tv and cell phone waves, each with different parameters and affecting the way our receivers capture those waves for our use, which becomes very apparent when mountains interfere with them.

 

There are many ways to manipulate solar rays before directing them to strike an absorbing surface that can be heated. 

The Greenhouse Effect: Absorption & Insulation 

It’s not easy to accumulate enough heat to cook with the sun so after the solar harnessing via the reflectors you’re going to need to hold onto as much of that concentrated sunlight as possible. In order to do this, the Greenhouse Effect is critical to any solar cooker. It is also a critical process by which our planet is made habitable. The Greenhouse Effect is "the process by which radiation from a planet's atmosphere (heated by the sun) warms the planet's surface to a temperature above what it would be without its atmosphere" according to Wikipedia.

CO2 is a critical gas in our atmosphere, which captures the suns heat and enhances the Planet's Greenhouse Effect, making our Planetary home habitable. Unfortunately, due to fossilized CO2 being released through the burning of fossil fuel (refer to our blog post "Peril or Promise" to learn more about this) we are enhancing this process to a currently unknown end. Fortunately, by you cooking on your solar cooker you are not only mitigating this process but also utilizing this science to create tasty food.... definitely a win win for you and our planet.  Once the sun passes through the tubes first layer of glass it needs an effective way to capture and hold that heat, which absorbing colors and materials make that possible. 

 

After this we need to prevent it from escaping, of which insulation is one of the best methods in which to do this. Whether it's fiberglass insulation, rigid foam insulation or cellulose, they all prevent energy escaping by sealing pockets of air. Glass, unfortunately, is not a good insulator and the problem with most solar ovens is that the heat rises out the top where a single layer of glass does little to hold the heat inside.  Fortunately, in the 20th century, vacuum technology became an important development with incandescent light bulbs and vacuum tubes for various technical applications, such as TV’s and radios. Outer space is an even higher quality vacuum, producing conditions that have raised awareness about the impact of vacuum properties. These are increasingly being featured on solar cookers (more on that when we talk about GoSun solar cookers).

 

Thermodynamics & Cooking

According to NASA, thermodynamics is “the study of the effects of work, heat, and energy on a system.” These principles are fundamental to successful solar cooking.

The efficiency of some solar cookers is estimated to peak out around 80%. That means 80% of the infrared, visible light and ultraviolet radiation from the Sun is turned into heat inside the tube’s chamber.

Conduction

Another type of heat transfer is when objects are in direct contact with each other. When an object is heated, the particles move faster and bump into nearby particles and ultimately transferring the energy to the particles of a object that make contact. This happens inside your solar cooker's cooking chamber when sunlight heats up the collector tube which transfers into the cooler cooking tray and food, changing the internal energy of all of elements involved. Different types of materials conduct heat better than others, for example metal is better than wood; we chose to use stainless steel for this reason (along with its durability).

Convection

This happens in liquid or gas which causes transfers of heat from the hotter areas to the cooler areas. When warm air or liquid rises, the cooler parts sink until it is heated, to rise again; causing a continual circulation pattern or “convection currents”.

 

Solar Cooker Design Types Compared

Solar cookers have been getting a lot of good press in the last months, and for good reason! Solar cooking is a great idea for anyone looking to reduce their fuel use, keep their kitchen cool or find a more convenient alternative to a conventional stove.

Luckily, if you're searching for a solar cooker, you now have more options than ever. From an oven that can bake a Turkey, to a stove that can cook a meal under clouds and snow, the technology of solar cookers has come a long way since your grade pizza box oven!

Comparing stoves is like picking a car; each model excels for certain uses and but may fall short in others. In fact, it's common for solar chefs to combine technology to meet the needs of their situation and environment. In order to demystify the options, we have created a comparison looking the most popular solar cookers on the market. Due to the nature of the comparison, we have compared cooker types rather than models, with exception to the GoSun solar cooking devices which have no parallels.  

Consider a few key questions before exploring your options:

• Do you have good continuous sunlight where you intend to cook?
• Are you willing to change cooking habits to adapt to a new technology?
• Do you plan on using the stove daily or just on occasion?
• Will you use your cooker at home or for on-the-go adventure?

Important aspects examined in the infographic below include: Speed, Capacity, Cold and Wind Performance, Low Light Performance, Attention Needed to Cook, Durability, Portability / Weight, Cook Style Versatility, and Cost.

 

Solar Cookers: The Results

Download our free PDF to find which one is right for you! 

To further clarify, we have expanded on each cooker type:  

 

Simple Panel Solar Cookers:

The panel cooker is an unparalleled winner in cost-effectiveness allowing tens of thousands to be deployed in refugee camps around the world. With more than 90 documented designs, each model varies a bit in the details but contains two primary elements: a heat absorbing pot and a reflective non-metallic panel (thus its namesake).

Perhaps the most well know basic panel cooker, the CooKit by Solar Cookers International uses a foil-lined cardboard for the reflective panel and can cook a full meal for 6 in a matter of hours. This model is a classic and has been utilized by people in need all over the world. 

Notable Models: Copenhagen, CooKit

Cost: <$50

Capacity: 5-6 Meals 

Primary Advantages:	Primary Disadvantages:
-Cost -Ease of Construction -Portability	-Low Max Temperature (≈120°C/ 248°F) -Unable to Fry Food -Varying Durability

 

Basic Box Solar Cookers:

A Basic Box Cooker is constructed of an insulated box capped by a single pane of glass, with a single reflector positioned above to expand its solar footprint. A black absorbing pot is placed inside the box and is locked in by the pivoting glass top, trapping the sun’s heat while allowing light to pass. 

This design generally obtains higher temperatures than a Basic Panel Cooker by virtue of its added insulation protecting the pot more effectively from wind and cold. There are many basic box-style cookers that can be made at home with simple materials. (For DIY plans take a look at the Solar Cooking Wiki here.) 

Notable Models: Easy Lid Cooker, Minimum Solar Box Cooker

Cost: ≈ $<40

Capacity: 4-8 Meals

Primary Advantages:	Primary Disadvantages:
-Capacity -Ability To Bake -Low Maintenance While Cooking	-Can’t Fry -Poor Low Angle Light Performance -Portability

 

Advanced Panel Solar Cookers:

For the sake of comparison, we have divided panel cookers into two general categories. Structurally similar to a Simple Panel Cooker above, Advanced Panel Cookers like the Hot Pot by Solar Household Energy, use an external greenhouse layer to create dead air space around the cooking vessel. This layer adds significantly to the pot's insulation value by providing a thermal buffer between the pot and the ambient air. In the case of the HotPot, this layer takes the form of a glass bowl covering the black absorbing pot. Other models create this barrier by elevating the pot on a heatproof trivot and covering the assembly with a heat-resistant plastic bag, often used for baking in a conventional oven. (Examples of different box cooker designs here.)

The reflectors are typically made of a more durable material such as anodized aluminum, and can easily collapse for storage. Cooking pots can vary in size but can generally feed between 4-8 people. 

With thousands on the ground in Mexico and other developing countries, the HotPot (like the panel cooker) is reliable for consistently Sunny and relatively temperate environments.

For a more in-depth review of the HotPot, take a look at this review by Solar Cooker at Cantina West.

Notable Models: HotPot, Sun Flair, All Seasons Solar Cooker

Cost: ≈$100 - $185

Capacity: 5-6 Meals

Primary Advantages:	Primary Disadvantages:
-Faster and Higher Max Temp than Panel Cooker -Low Maintenance	-Not As Rapid to Cook as Others -Moderate Capacity -Poor Absorption of Winter Sun

Parabolic Dish Solar Cookers:

Rather than insulating, parabolic cookers use a reflective dish to concentrate large amount so sunlight onto a cooking vessel. This sheer amount of energy can top temperatures in excess of 250°C and allow users to cook using a frying pan as if on a stove top.

This design is ideal for boiling grilling or frying on sunny days but requires periodic re-adjustment to track the Sun. 

Notable Models: SolSource, SK14

Cost: ≈$549

Capacity: 4-8 Meals 

Primary Advantages:	Primary Disadvantages:
-Culinary Versatility (Fry and Grill) -Cooking times similar to conventional stove top	-Require periodic adjustment to track Sun -Low performance in intermittent/ diffused light -Dangerous if used incorrectly -Portability -Cost

 

Advanced Box Solar Cookers:

In addition to an insulated box, Advanced Box Cookers utilize a more sophisticated reflector system that can better absorb off angle sunlight. Interior racking for the cooking pot is used to keep heat from leaching into the box’s floor. Perhaps the most well-known design of the style of the Sun Oven which uses four flat reflectors that can fold flat for transportation.

This variety of solar cooker excels in capacity and use on primarily sunny days. DIY designs also exist such. such as the Heaven’s Flame Solar Cooker, which can be made in a few hours with simple materials. 

Notable Models: Sun Oven, Heaven’s Flame

Cost: ≈$350

Capacity: 4-10 Meals

Primary Advantages:	Primary Disadvantages:
-Capacity -Ability To Bake -Requires little adjustment to track Sun -Faster to Heat Than Normal Box Cooker	-Difficult to Fry -Poor Low Angle Light Performance -Portability

 

GoSun Grill 

The GoSun solar cookers are unique in their unparalleled reliability and low light performance (this applies to any of GoSun's solar cookers, particularly the GoSun Sport and the GoSun Fusion). Second to the parabolic dish cooker in speed, tube cookers can hit temperatures in excess of 480°F/250°C and stay hot for hours after the Sun sets. Though a relatively new innovation, this style of cooker has received significant media attention as of late.

At the core of the technology is a solar vacuum tube that acts as a near perfect insulator. Light is reflected onto the tube's internal absorber surface, which is then trapped inside the vacuum layer. This unparalleled insulation allows vacuum tube cookers to operate in frigid environments with little, if any change, in performance. 

The stove also uniquely utilizes compound parabolic reflectors, with the ability to reflect light from a wide range onto the cooking tube. This ability to absorb diffused light gives the GoSun cookers the unique ability to cook even in light overcast. This is further amplified by the tube's broad spectrum absorbing surface that can convert both ultraviolet and visible light into useable heat.

Solar vacuum tubes do however require sensible handling to keep from breaking. For a long life, don't preheat the stove empty for long periods or drop it on hard surfaces. (More best practices here.) GoSun does, however, offer a Two Year No Questions Asked Warranty on all of its solar-powered cookers. 

The GoSun Grill also has the potential to be paired into a hybrid solar electric cooking system which is currently under development for release in late 2018. 

 

Cost: $599

Capacity: 6-8 Meals 

Primary Advantages:	Primary Disadvantages:
-Diffused and Intermittent Light Performance -Culinary Versatility (Bake, Roast, Fry) -Minimal adjustment to track Sun -Capacity -Speed	-Cost -Moderate Durability -Weight

 

GoSun Sport 

GoSun Sport vacuum tube solar cooker takes the best qualities of the Grill: low light performance, speed, and versatility, putting them in a lighter and faster cooking package. 

The Sport has the ability to bake, roast steam or fry a meal in as little as 20 minutes in full Sun and pack up into a 7.5lb package to be taken on the go.

 

Cost: $279

Capacity: 2 Meals

Primary Advantages:	Primary Disadvantages:
-Speed -Diffused and Intermittent Light Performance -Culinary Versatility (Bake, Roast, Fry) -Minimal adjustment to track Sun -Portability	-Limited Capacity -Cost -Moderate Durability

GoSun Fusion

See our latest innovation here: the GoSun Fusion, which let's you cook at night

 

Picking the best solar oven, cooker or stove for your needs can be a challenge, but there are other great resources to help make a decision. For more information on solar ovens and stoves, take a look at the Solar Cooking Wikia by Solar Cookers International.

For more info on the GoSun Solar Coookers, including larger and smaller models not mentioned above, take a look at our solar cookers here.  

 

 

Box Solar Oven: Advantages and Disadvantages

The box solar oven is one of many types of solar oven designs. In this article we will briefly go over its advantages and disadvantages compared to others.

When adventurers, environmentalists, and anyone who wants to take advantage of a free energy source looks into a new way to cook food, they are never far from solar cooking. Solar ovens and cookers are good for the local environment because they produce no smelly or toxic waste and they emit no greenhouse gases. They also require no fuel other than plentiful sunlight, which means no fuel costs. Many are easy to maintain and clean, and so it makes sense to adapt one’s cooking habits to use a solar cooker or oven.

Given that solar cookers are growing in popularity different solar ovens and solar cookers create different experiences for the user. Some solar chefs want portability above all else and are willing to pay for durable materials and a compact design. Others want the economic impact of a cooker to be low, so that it can be mass-produced and distributed quickly, even if some of the features are less impressive. Regardless of how you want to use your solar oven, it is valuable to look at the options before you settle on a particular model.

The box solar oven is quite simple in design. Some of them are designed to be effective, inexpensive, and able to be created quickly and easily by anyone using common materials. The structure involves a reflective box which contains the pot for the food, along with a lid and a single reflective panels that concentrates sun into the cooker. There are also more complex models which have multiple collapsible reflective panels rather than just the one flap. Regardless, these ovens tend to be on the less expensive side, though depending on the materials they are also more vulnerable to wear and tear over time. They can bake and create meals for large amounts of people, sometimes even 8-10, but they do poorly with low angle light and are somewhat less portable than other solar cookers.

Vacuum Tube Solar Cookers, on the other hand, have some very different benefits. These cookers concentrate the sun onto a vacuum tube, which slowly absorbs all of that heat without letting it escape. The food inside the tube can become cooked or baked quite quickly and the reflectors use relatively less surface area. 

At the same time, Vacuum Tube and the box solar oven offer different options to the world, they also both offer quite good capacity for cooking and the option for doing some baking, which can be a struggle in other forms of solar cookers.

These are certainly popular options in the solar oven world, but there are even more options to explore. To see all major solar cooking technology compared, check out this blog post.  

 

Dish Solar Cookers vs Vacuum Tube Solar Ovens 

Solar cooking is growing in popularity because people are realizing two valuable truths: no one wants to pay for fuel when there is plentiful free sunshine, and many are becoming concerned with their environmental impact. Using the sun to harness enough heat to cook food is a great method to both reduce one’s greenhouse gas emissions and save some money from using less fuel at the same time. There are numerous solar oven designs, and this article will take you through a couple of the major ones. 

Different solar oven designs have different advantages; as people look for the best solar ovens online, they are often tempted to try the model they run across first. However, in the cases of dish solar cookers and vacuum tube solar ovens, they are valuable in different contexts. Some people, like adventure travelers, are looking for an extremely portable oven or stove, while people who want to cook in their backyard may value a range of available cooking options over the ability to move their stove.

 

Solar Oven Designs: Dish Solar Cookers

Dish solar cookers are great for speed of cooking, durability, and versatility. Dish solar cookers use a large parabolic dish to focus the sun’s rays to create a spot of intense heat. You can use them to cook or fry a variety of items since they concentrate the sun’s energy on a single pot or pan in the center. The downsides are that they need to be adjusted to where the sun is, and they can be costly and somewhat dangerous if operated incorrectly. They can often be a bit expensive and take up a lot of space, which isn’t a problem if you have plans to keep your Dish in a particular location long-term and use it frequently.  On a sunny day, they can truly shine.

Solar Oven Designs: Vacuum Tube

Vacuum tube solar ovens, on the other hand, have some very different contextual advantages and disadvantages. One of the most interesting positives is that they are quite portable and don’t need a lot of attention, since their design allows them to capture light for long enough to cook without constant adjustment. While they are not always inexpensive, they excel in weight, versatility, and ability to work with cloudy or low light environments. The GoSun Sport is a good examples of this technology.

In light of these two solar oven designs, if you need your food quickly and don’t mind using a large device to do it, a dish solar cooker will often be a good option. However, if you want a cool-to-the-touch item that requires less space and has increased portability, you might be a better candidate for a vacuum tube solar oven. Both styles are fairly versatile, but your needs will ultimately determine which fits your choices most.

While Dish and Vacuum Tube cookers are certainly popular options in the solar oven world, there are even more options to explore. To see all major solar cooking technology compared, check out this blog post.

 

The Parabolic / Vacuum Tube Hybrid Solar Cooker

This explains how the technology works and its comparable advantages and disadvantages to conventional cooking. We'll also describe why we think the GoSun makes the best solar ovens.

The GoSun's patented solar cooking technology can bake, boil or fry a meal using nothing but energy from the sun, even in clouds, wind and freezing conditions. Heating up to 550°F/280°C while staying cool to touch, the stove's performance is only made possible from a combination of ideal materials and clever engineering.

Let's take a look inside:

 

The Solar Vacuum Tube

The core of GoSun Technology is with the vacuum tube cooking chamber, which absorbs light while acting as a perfect insulator. We think of it as a physics hack, one of thermodynamic’s only free lunches. 

A perfect insulator? That’s right. Between the tube’s two layers of borosilicate glass (wiki link), is a pocket of beautiful nothing (AKA outer space). Heat requires a medium to transfer. Without a thermal bridge, the heat absorbed by the stove collects rapidly.

How is the heat absorbed? Great question! The internal face of the tube is coated in three layers of metal: aluminum nitride, stainless steel, and copper. Placed on the inside of the vacuum (away from your food), these three layers work in unison to trap both viable light and ultraviolet, allowing one to cook in a light overcast.

• Aluminum Nitride: An absorber common in the semiconductor industry with fantastic energy absorbing properties.
• Stainless Steel: Moves heat evenly, cooking food cooking from 360°. 
• Copper: Reflecting heat, in the form of infrared radiation, back into the tube.

What is borosilicate glass? Borosilicate glass is known for its chemical and thermal resistance, making it a go-to choice for bakeware, LED lights, and lab equipment.  

So this is high-tech, right? This technology is new but not cutting edge. GoSun founder and solar energy expert, Patrick Sherwin, got the idea while working with a solar vacuum tube water heater. The tubes used for solar hot water heaters have been known to last decades on roofs around the world. 

 

Compound Parabolic Reflectors

Compound parabolic reflectors concentrate light from a variety of angles onto the cooking tube. This means that there's little need to re-adjust the stove while cooking and even diffused light (such as light going through clouds) can be focused on the tube.

Roland Winston invented the first compound parabolic concentrator (CPC) in 1974, a breakthrough technology in solar energy. His discovery has now been used extensively in solar energy collection, wireless communication, and biomedical research.  

Cook Times With Our Solar Cookers

Solar cooking times vary but this chart will help you figure out what to expect when dealing with the weather. 

Heat Bank Technology (GoSun Only)

 

This simple innovation allows GoSun's solar ovens to cook steadily with inconsistent sunlight and in some cases, cook small meals or leftovers without sunlight. GoSun's tubular oven chamber is designed with a highly conductive aluminum chassis. While in sunlight, it channels heat into a heat bank underneath the tray. This heat bank allows you to store heat until you're ready to use it, meaning once up to temperature, the Heat Bank will help guarantee a consistent cook, even when the sun is lacking.

 

7 Tips for Using a Solar Cooker

 

2. Set A Timer

Treat the stove like an oven. Perhaps the most common mistake made by new GoSun users is underestimating how quickly food can cook on a sunny day. To prevent petrifying your potatoes, set a timer or just ask Siri to remind you. 

 

 

3. Line the Tray for Easy Cleanup

Tray liners are a great way of limiting mess and quickly transitioning from one dish to the next. There are a few techniques you can use depending on your culinary preferences. 

 

 

6. Vent Moisture to Cook Crispy Dishes

Looking to get a good crust on your baguette? Here's the secret: once the bread has fully risen, open the tray and let out the moisture for a few seconds. Then continue cooking with the tray cracked open for another 5 minutes or until crunchy. 

The same technique can be used for meat with the GoSun Grill's drip tray, to get a more crispy texture on those chicken wings. This will lead to the right consistency for any of your solar cooking dishes.

 

7. Get Inspiration From the GoSun Recipe Blog and Community Kitchen Facebook Page

It's fun to experiment, but even Picasso needed some inspiration! Visit the GoSun Recipe Blog to explore our latest creations, such as our Solaricious Salmon Bake in a Butter Rub or our healthy and hearty Vegetable Quinoa Pilaf.

Have questions or ideas about solar cooking? Jump onto the 3,500 member strong GoSun Community Kitchen Facebook Page and join the discussion! 

 

Solar Cookers For Sale

Looking for solar cookers for sale? Are you planning a long camping trip, a simple day at the park, or a backyard dinner party? Maybe you’re thinking about getting prepared for emergencies such as long-term power outages. Or perhaps you just want to cook the same things you always do, but in a more environmentally friendly way.

Whatever your situation, GoSun offers many different solar cookers for sale to meet your needs. Read on to compare the various models available within this ingenious, patent pending line of solar stoves. Whichever GoSun you choose, you’ll be cooking delicious food, efficiently and easily.

 

GoSun Dogger

Perfect for: Picnics or hiking

Capacity: One meal

Time required: 10 minutes

Weight: 1.5 lb

Cook two hotdogs or sausages in just ten minutes. The vacuum tube cooking chamber provides fantastic heat dispersal to cook evenly and thoroughly. Use the multi-position base to setup the Dogger just about anywhere and capture sunlight from almost any angle. It’s light enough to carry in a backpack and easy to use for anyone!

Order the Dogger Plus and you’ll also get a solar cooking educational kit, a padded carrying case, temperature probe, sundial, ray tracing laser, and experimental reflector.

Click here to order GoSun Dogger

Click here to order GoSun Dogger Plus

 

GoSun Sport

Perfect for: Camping, RVing, picnics

Capacity: Two meals

Time required: 10 minutes

Weight: 7 lb

Bake, roast or steam a meal for two people in minutes, at temperatures up to 550°F (290°C). The GoSun Sport folds into a slim package that’s easy to take along when you go camping or picnicking.

Order the Pro Pack and you’ll also get a padded carrying case for secure travel, an extra cooking tray so you can cook one dish while prepping the next, and non-stick silicone baking pans (these come in extra handy!).

Click here to order GoSun Sport

Click here to order GoSun Sport Pro Pack

 

Order Your Solar Cooker & Join the Revolution

We offer various solar cookers for sale to meet your needs. Each grill comes with a two-year warranty and 30-day money back guarantee. What are you waiting for? Choose the perfect GoSun and start cooking with the power of the sun!

Shop GoSun's Solar Cookers ➞