Yep, by definition solar depends on sun, though ambient air temperature apparently has little effect. This means solar effectiveness varies by season and climate. You wouldn't want solar in a winter BOB in a cloudy climate, but if that climate has a sunny summer ....

But I know I already change gear, like my sleeping system, in my BOB and car kit for winter even here in California. Ditto for the rest my camping and hiking gear. A great piece of gear with seasonal limitations is nothing new.

“Clear weather is essential. On partially cloudy days, solar cooking takes longer. On extremely cloudy days, we suggest that you rely on the old energy-consumer standbys like house ovens or barbecues.

Outside temperature has little effect on solar cooking; if the sky is clear, you can cook on a snowbank high in the mountains.”

http://www.azsolarcenter.com/technology/solcook-5.html

Fast and light! Fast and light!

Jeez Louise! Does anyone even really consider anything else?

If you really want instant cooking on a camping trip or a survival situation, all you have to take with you is a generator and a microwave.

As you might have noticed, this topic is in the Long-Term forum. Let's see how long the wood supply lasts, esp if there are others around. Just how much petroleum-based fuel do you intend to store? Carry?

Sue (yes, as a matter of fact, I AM in a bad mood. How could you tell?)

While a solar water heater can be unattended for hours, it does in fact take hours to boil the same amount of water a Thermette or Kelly Kettle can do in 5-min or less. Also you should re-aim the solar cooker throughout the day to keep it pointed at the sun so it’s not the set it up and forget it thing you make it out to be. The setup time for both would be about the same I would imagine. The Thermette fills with water in just a few seconds, but it does take a min to get the fire going. But 5-min from starting the fire I will have boiling water, this process is repeatable even faster for any additional water boiling as the fire is already started.


As far as building a solar cooker from materials found, I would say it’s a lot easier to find a few sticks then the material to make a solar water heater.


And 2 or 3 min of picking up sticks will give me enough free fuel to boil several gallons of water. I can also cook with the Thermette (as can those that have a Kelly Kettle) while boiling the water. It gives me a lot of choices in how to do the job in a very short time.


Yes people may be able to see the smoke from the Thermette or Kelly Kettle, but it produces less smoke then you may think. And as far as the remains being found. Is this really an issue? If so I would use my alcohol stove or Svea stove, or dig a small area to use the Thermette in and when done spread the ashes around and cover the spot over with the removed dirt. I have done this with small camping / cooking fires in the past and you are hard pressed to see that a fire was made there.

If trying to remain stealthy I would suggest that a 5-min fire is no more going to be seen then spending all day in a spot waiting for a solar water to boil water. But again I don’t see this as an issue at all.


And if there is a fire ban on in the area I’m camping in, the Thermette works on top of any camp stove. It works slower this way, not as fast as with a wood fire. But it’s still much faster then a solar water cooker.


I’m not trying to take apart the idea of using solar as a way to cook and make drinkable water. I’m just pointing out how the Thermette & Kelly kettles work and can be used, and continuing the debate to help all of us get the most information we can to be ready for any given unknown situation.

Good post, BobS.

I have no knock on the Thermette. I expect I will eventually own and use one; especially for car and canoe camping.

Cooking solar takes some practice. Mid-day is usually best. Better portable solar setups can reach in excess of 250 degrees in about 30 minutes of full sun, regardless of ambient air temperature. Time to pasteurize or boil is going to depend on altitude but, except for massive parabolic cookers, solar will never be as fast as a Thermette.

There are some foods, especially baked goods, that can be cooked in less than an hour, depending on conditions.

You can cook soups, stews, casseroles, and other dense foods unattended for substantial periods of time with solar. There is no need to keep adjusting the cooker to track the sun, but you can if you want.

With the efficiency of modern solar a typical cycle begins with pointing the solar cooker so that it will get best sun from 11 to 2. Earlier than that it is warming, during peak it is cooking, and after peak it is keeping food warm. Solar cookers are like other slow cookers, you really cannot burn food very easily. So “set it and forget it” as Ron Popeil (sp?) would say; go fishing or take a nap.

I agree that, except in the most desperate of escape and evasion bug outs, the smoke and residues of a small fire are not a big issue. But I think many of us know that even burying, or spreading and covering, evidence of a fire leaves at least telltale smell, as does the downwind smoke plume long before and long after you can see actual smoke. So if being found or tracked, or just minimizing your impact on the land is an issue, then solar might be a better option.

In many places picking up a few handfuls of fuel will not be a problem, though in all California parks and many local and national parks it is technically illegal. Much of the time you probably also are supposed to get a fire permit, and at times the permits will not be issued due to fire danger. I agree that the no-harm-no-foul rule will probably apply most of the time, but solar eliminates these legal concerns. This may be a consideration for you, perhaps especially if you are trying to model behavior you want youngsters to follow.

The stealth scenario presumed you were already holing up for the day and traveling at night only. Again, I agree it is only relevant in extreme evasion situations and it is up to you if you want to think about preparedness for such cases. My current BOB plan includes an alcohol stove. In fairness, if aerial pursuit was an issue, I would not want to deploy a large reflective solar cooker either.

Making a solar cooker from found materials is definitely harder than assembling found fuel for a Thermette you are already carrying and could be impossible in some situations. But of course that is an apples and oranges comparison. If solar makes sense you can put together a game plan for making a solar cooker more easily than making a Thermette.

By the way, if you are traveling you can sometimes set up a solar cooker to cook as you go. In a canoe or on top of a vehicle, would be examples.

Is solar perfect for all applications, all the time, everywhere? Nope. But is a Thermette, or an alcohol stove, or a pressurized gas stove?

I’d be interested in seeing pictures of the solar cooker you make. If you make one, take pictures and post them and the results.

Will do.

This weekend I am testing a couple of cardboard box solar cookers. I intend to cook a stewed chicken in one and chili in the other. I will report.

I am having technical difficulties with photos. I take them and can upload them to my computer, but my PhotoBucket account no longer recognizes me. Email to the company has not been answered yet.

Wood supply will last forever, a Thermette or Kelly Kettle takes a surprisingly little amount of wood. And wood is a renewable resource. In my yard more of it falls to the ground then I could use in the Thermette. In a disaster situation construction debris is abound everyplace. In almost everyplace on the planet you will not have a problem finding burnable fuel.

Counting my trees and the neighbors tree that drop things in my yard there are 5-trees.

In almost everyplace you will have more trees then that to harvest firewood from.


I went to a music festival a few weeks ago with 50,000 people in attendance. (With all those people, a lot of them grabbing all the wood they could find. As it’s against the law in Ohio to transport firewood, it has to be bought locally or scavenged on site)I was able to have an abundance of wood to use, in fact even using the Thermette to heat enough water for 3-people to take showers and wash dishes once a day I still had a small pile of wood left over at the end of the week.


I would like to see a good solar cooker / water heater in use, but I don’t think in a survival situation it comes close to burnable fuels for generating heat. That’s why I went the way I did, it works well.

"I don’t think in a survival situation it comes close to burnable fuels for generating heat."

Large array solar can generate temperatures into the thousand of degrees Farenheit [ see for example http://www.eia.doe.gov/kids/energyfacts/sources/renewable/solar_plants.html#Parabolic%20Troughs], though typical small cooker designs get into the 250 - 450 degree Farenheit range by design [ see for example . http://home.att.net/~cleardomesolar/parabolic.html].

Improvised solar can be as simple as a board, a tire, a black pot , and a pane of glass:
http://www.solarcooking.org/plans/tire_eng.htm
Making a solar still and cooker from improvised materials should be on the list of survival skills. Check out this parabolic solar cooker basket made of found materials, including in part of of blackberry branches and tin can lids!
http://www.appropedia.org/Parabolic_Basket_Solar_Cooker

“The next time we tested the cooker, we used a quart-sized jar that was painted black and created dead air space by placing a transparent pickle jar over it. That day, we set up the jar at 11:20 am on a warm sunny day without wind. After an hour, the water inside the jar was starting to bubble, meaning that we surpassed pasteurization temperature. After about two and a half hours the water in the quart jar was at a rolling boil.”

Like all survival gear, solar needs to fit the situation. For your fixed site survival retreat or large bug out vehicle, a large solar device is possible and smaller types easily incorporated. For man-portable solo survival situations, you are probably looking at a small, folding system which will cook and pasteurize water, but may not boil water except in near ideal solar conditions.

BobS and I have explored some of the virtues and vices of solar versus Thermette in earlier parts of this thread. I think going with a Thermette makes sense much of the time; I intend to buy one in the future. I think going solar has tremendous potential and am exploring its use now; many others around the world have been using solar on expeditions for more than a century.

My main point: consider taking a hard new look at solar.

That tin can lid cooker was interesting. But the math! I hate math!!!

So don't calculate, OBG. Use something alreday parabolic like the inside-of-an-umbrella projects. I bet as a practical matter you can figure out where curved relector panels focus their light / heat against a target like a piece of cardboard just like you zero in with a magnifying lens.

Or do as I am: start with a cardboard box project instead of one that is parabola-based. My thought is to then duplicate the box with thin aluminum sheets lined with foil at first, then with super reflective material like:

http://home.att.net/~cleardomesolar/solareflexpanels.html