Any thoughts on solar ovens?

silentrust

Just been browsing instructables looking at solar ovens as a green way of cooking food and a potential backup if I run out of solid fuel if the SHTF, one example here:



Looks simple enough even for the DIY inept like myself. The advantages if it functions correctly are obvious - a continual supply of cooked food and warm water for cooking/washing/drinking copious cups of tea.

However I get the impression that these instructions are written by North Americans who of course live in a vast desert by and large, so get much more sunshine than we do.

Does anyone here in Ireland have experience of using this type of oven? Is it not worth the bother considering the frequent cloud and drizzle in which the Emerald Isle is enveloped?

eirator

Any thoughts on solar ovens?

One word IRELAND - is it worth the effort for the one day in summer when it might work?

silentrust

eirator wrote: »

Any thoughts on solar ovens?

One word IRELAND - is it worth the effort for the one day in summer when it might work?

The reason I asked is I wasn't sure how much direct sunlight is needed to cook food adequately - presumably it depends on the oven in question to an extent, would be interested to know if anyone has tried to use these outside the single day of summer Ireland gets! :-)

Tabnabs

I think anywhere north of the English Channel would be pretty worthless.

silentrust

Tabnabs wrote: »

I think anywhere north of the English Channel would be pretty worthless.

Have received a PM from a user who has made use of one to heat water in the past but outside Summer a solar oven in Ireland is just a paperweight apparently. Heigh ho!

mawk

I think you might be better off with a trangia and a haybox cooker

eirator

mawk wrote: »

I think you might be better off with a trangia and a haybox cooker

Might depend where you are intending to use them?

Trangia is a great camping cooker for anyone on the move but why limit yourself to a lighter weight cooker if you are staying put. I say that because I don't see anyone lugging the bulk (not weight) of a haybox around and the OP has mentioned bugging in in other threads.

We do a lot of our cooker top cooking at home on gas and a cylinder lasts 3-5 months (never used more than 3 in one year but boil water with electric) so if anyone is bugging in it might be easier to change over the way they cook now from electric to bottle gas and just stock up on gas cylinders. Then when the power goes thats one thing you don't need to worry about at least in the short term. The addition of a haybox could save a lot of gas and extend fuel supplies even more.

Longer term I have plans for an outdoor bread oven which for those who have a survival group plan could be a good community project. Which reminds me, I must check the price of firebricks and stock up on them as they are very useful for a lot of heating and cooking projects.

Solair

They work in Spain or California but in Ireland you definitely won't get enough solar energy to make it work.

silentrust

eirator wrote: »

Might depend where you are intending to use them?

Trangia is a great camping cooker for anyone on the move but why limit yourself to a lighter weight cooker if you are staying put. I say that because I don't see anyone lugging the bulk (not weight) of a haybox around and the OP has mentioned bugging in in other threads.

We do a lot of our cooker top cooking at home on gas and a cylinder lasts 3-5 months (never used more than 3 in one year but boil water with electric) so if anyone is bugging in it might be easier to change over the way they cook now from electric to bottle gas and just stock up on gas cylinders. Then when the power goes thats one thing you don't need to worry about at least in the short term. The addition of a haybox could save a lot of gas and extend fuel supplies even more.

Longer term I have plans for an outdoor bread oven which for those who have a survival group plan could be a good community project. Which reminds me, I must check the price of firebricks and stock up on them as they are very useful for a lot of heating and cooking projects.

Thanks again Eirator, very touched that you remembered my strategy (if you can call it that) revolves around bugging in. My father and his partner cook with bottled gas though they seem to need more than you do, perhaps they're a bit too liberal with their usage? I do remember a bottle running out before his pension was due forcing us to cook spaghetti bolognese on the BBQ, very tasty! :-)

Am I right in thinking the Haybox works along the principle of reflecting heat back into the cooking container? I have read it can reduce the energy required for cooking as much as 40% but have always been a little sceptical, as I always am when trying to apply things I learned in school to everyday life - anyone here made use of one?

eirator

The haybox doesn't so much as reflect the heat as just stop it escaping but a layer to reflect heat back wouldn't go a miss. There was a bonniebede thread that looked into them in more detail. I've never used one to cook with but have used them to keep food hot and they do that great. We use all cast iron saucepans and casseroles and I suspect that they would work well with a hay box as the cast iron would hold a lot of heat to keep the cooking process going.

I said we use gas but we boil most water in an electric kettle and have and electric oven as well as a multi-fuel cooker so gas is just part of our strategy.

silentrust

eirator wrote: »

The haybox doesn't so much as reflect the heat as just stop it escaping but a layer to reflect heat back wouldn't go a miss. There was a bonniebede thread that looked into them in more detail. I've never used one to cook with but have used them to keep food hot and they do that great. We use all cast iron saucepans and casseroles and I suspect that they would work well with a hay box as the cast iron would hold a lot of heat to keep the cooking process going.

I said we use gas but we boil most water in an electric kettle and have and electric oven as well as a multi-fuel cooker so gas is just part of our strategy.

Sounds ideal, I have a small stove with hexane fuel tablets which we use to boil water and cook small amounts of food occasionally for practice if nothing else - would much rather have one that can make use of scavenged deadwood and twigs but will have to wait until next month's paycheque!

eirator

silentrust wrote: »

Sounds ideal, I have a small stove with hexane fuel tablets which we use to boil water and cook small amounts of food occasionally for practice if nothing else - would much rather have one that can make use of scavenged deadwood and twigs but will have to wait until next month's paycheque!

If you want to boil water there is NOTHING better than a Kelly Kettle it burns free fuel, twigs, bits of stick, deadwood, pine cones and most things that can be made to burn including I believe camel dung but then if we had that easily available your solar oven would be a better bet

The only problem is the Kelly Kettle is ONLY for outdoor use and don't be using the hexi stove indoors as iirc the fumes aren't good for you.

The attachments you can get for Kelly Kettle to use it like a stove are of limited use but fit in well with some peoples mode of operation.

I currently don't have a Kelly Kettle as I can't decide which one to get (I really want 2:o) but from experience the small one works well as does the largest but the medium one doesn't have the best flue to size ratio so seems slightly less efficient.

A haybox shouldn't cost much to make its just a box with a lid/door stuffed with insulation. Long term convert an old fridge, even a large cool box can be used with more insulation.

silentrust

eirator wrote: »

If you want to boil water there is NOTHING better than a Kelly Kettle it burns free fuel, twigs, bits of stick, deadwood, pine cones and most things that can be made to burn including I believe camel dung but then if we had that easily available your solar oven would be a better bet

The only problem is the Kelly Kettle is ONLY for outdoor use and don't be using the hexi stove indoors as iirc the fumes aren't good for you.

The attachments you can get for Kelly Kettle to use it like a stove are of limited use but fit in well with some peoples mode of operation.

I currently don't have a Kelly Kettle as I can't decide which one to get (I really want 2:o) but from experience the small one works well as does the largest but the medium one doesn't have the best flue to size ratio so seems slightly less efficient.

A haybox shouldn't cost much to make its just a box with a lid/door stuffed with insulation. Long term convert an old fridge, even a large cool box can be used with more insulation.

Just had a look at the website, many thanks for this. I like the look of the small one as it seems to me better economy of fuel to heat up small amounts as they're needed - bearing in mind you can always empty and refill it with cold water - just don't use it to run any baths...!

Hot water is a luxury I could really do without losing. Years of public school ice cold showers have taken their toll - perhaps there'd be a way to upscale something like this to a full scale boiler?

eirator

silentrust wrote: »

Just had a look at the website, many thanks for this. I like the look of the small one as it seems to me better economy of fuel to heat up small amounts as they're needed - bearing in mind you can always empty and refill it with cold water - just don't use it to run any baths...!

Hot water is a luxury I could really do without losing. Years of public school ice cold showers have taken their toll - perhaps there'd be a way to upscale something like this to a full scale boiler?

Just throw money at the problem Get a Frontier Stove and its water boiler attachment although the one review of the water boiler isn't great.

I took a look at the Frontier Stove in that outdoors shop on the quays in Waterford and while I like the design I thought it was a bit thin, but I suppose you have to compromise on weight on an item like that.

The larger Kelly Kettle is the one to get if you are not going to back pack it. Its what has put me off getting one, the little one only boils enough for a mug and a bit of the size mug I use but the bigger ones are just a bit big to carry solo.

silentrust

eirator wrote: »

Just throw money at the problem Get a Frontier Stove and its water boiler attachment although the one review of the water boiler isn't great.


I took a look at the Frontier Stove in that outdoors shop on the quays in Waterford and while I like the design I thought it was a bit thin, but I suppose you have to compromise on weight on an item like that.

The larger Kelly Kettle is the one to get if you are not going to back pack it. Its what has put me off getting one, the little one only boils enough for a mug and a bit of the size mug I use but the bigger ones are just a bit big to carry solo.

Most interesting, will see if finances allow then give you all a full review.

I take it then your strategy is centred around bugging out? A fortified cabin in the woods where you can survive as the world burns?

Returning to the topic at hand one of my survival buddies from back in Blighty says that solar ovens are useless for bread apparently, so perhaps another reason to get one that runs on twigs.

eirator

Bugging in with a good bit of gear packed and ready to bug out. In fact various levels of preparedness including grab bags if we needed to leave in a couple of minutes down to a few boxes of stuff that would make bugging out a lot more comfortable assuming transport is available. Cars would also carry a few useful basic survival items at all times.

jaqian

What about a coke can stove...
http://www.thesodacanstove.com/alcohol-stove/how-to-build.html

silentrust

jaqian wrote: »

What about a coke can stove...
http://www.thesodacanstove.com/alcohol-stove/how-to-build.html

Brilliantly innovative Jaqian many thanks, I have printed this and added it to my ongoing SHTF ring binder (on the basis you may not be able to look it on Digg come the apocalypse).

Have you tried this before? I suppose you'd need a fewof these to get anything cooking properly?

eirator

They cook very well, effectively the same as the burner part of the trangia and many other meths stoves.

If you are looking for something really lightweight they are ideal and can be made while out in the field if necessary but you still need a supply of meths.

silentrust

eirator wrote: »

They cook very well, effectively the same as the burner part of the trangia and many other meths stoves.

If you are looking for something really lightweight they are ideal and can be made while out in the field if necessary but you still need a supply of meths.

Well said chief, I suppose that's the attraction of the solar oven in that the Sun is an abundant resource (outside Ireland and Britain ).

Still there is no shortage of twigs out there. Certainly safer to store wood than alcohol in any case.

maddragon

I have a proper solar oven for demos etc. brilliant when you have direct sunlight. As useful as a chocolate teapot if you don't. In full sun it will cook a full chicken in about 2 hours. Great thing is you will never burn the food even if you head off for the day because it will move out of the suns path as the day wears on. I'm lucky to get 15 days a year out of it in this place though (Cork)

silentrust

maddragon wrote: »

I have a proper solar oven for demos etc. brilliant when you have direct sunlight. As useful as a chocolate teapot if you don't. In full sun it will cook a full chicken in about 2 hours. Great thing is you will never burn the food even if you head off for the day because it will move out of the suns path as the day wears on. I'm lucky to get 15 days a year out of it in this place though (Cork)

Thanks Maddragon, question answered it seems - did you build the oven yourself or buy a pre-made one? Very jealous you're in Cork!

H.O.T.A.S.

Whilst not ideal for Irish weather in terms of cooking a meal how would a solar oven fair up if used for food preservation? Can you make/modify one as a dehydrator?

maddragon

I bought a premade one and it can be used as a dehydrator.

silentrust

maddragon wrote: »

I bought a premade one and it can be used as a dehydrator.

Most promising! I have toyed with the idea of buying a hydrator but so far only growing enough strawberries to be eaten immediately. Let's hope one day there is a surplus! :-)

eirator

silentrust wrote: »

Most promising! I have toyed with the idea of buying a hydrator but so far only growing enough strawberries to be eaten immediately. Let's hope one day there is a surplus! :-)

LOL you obviously haven't been gardening long!

Some fruits are best eaten immediately!

The problem is Plan A) Grow enough food to survive soon becomes plan God that was good lets eat it now. You really need a few years experience before you can grow enough to satiate Plan and have enough left for the primary Plan A), unless of course you don't have any taste buds.

silentrust

eirator wrote: »

LOL you obviously haven't been gardening long!

Some fruits are best eaten immediately!

The problem is Plan A) Grow enough food to survive soon becomes plan God that was good lets eat it now. You really need a few years experience before you can grow enough to satiate Plan and have enough left for the primary Plan A), unless of course you don't have any taste buds.

Only for a year or so I'm afraid, my SO really is the expert. She does it to save money and because she is a flower child. I do to batten down the hatches come the Apocalypse - having said that I have seen dried strawberries but agree they're probably best eaten off the bat...

...Anyone had experience making jams? That's what I'd like to do next. Have bought some jars just for the purpose.

eirator

silentrust wrote: »

Only for a year or so I'm afraid, my SO really is the expert. She does it to save money and because she is a flower child. I do to batten down the hatches come the Apocalypse - having said that I have seen dried strawberries but agree they're probably best eaten off the bat...

...Anyone had experience making jams? That's what I'd like to do next. Have bought some jars just for the purpose.

Its interesting that some of the stuff we talk about here is really just the lost art of house keeping. 50 years ago making jam and pickles from summer excess would have been automatic now its something an enlightened few do because it tastes so much better than shop bought and even fewer do because its part of self sufficiency.

silentrust

eirator wrote: »

Its interesting that some of the stuff we talk about here is really just the lost art of house keeping. 50 years ago making jam and pickles from summer excess would have been automatic now its something an enlightened few do because it tastes so much better than shop bought and even fewer do because its part of self sufficiency.

cf. Encyclopedia of Country Living. :-)

nigra

What with the good weather and the need to keep young children occupied outdoors, I managed to boil 500mls of water for my first cup of tea from a DIY solar oven and then hard boil a couple of eggs without really trying in my back garden.

I glued kitchen foil to a cardboard IKEA box to make reflector panels. Then I put a water filled black pot inside a clipped oven bag, all under the glass dome of a cake dish and placed the reflector panels to concentrate the sunlight onto it. It took an hour initially from 1pm to heat the water (which turned out to be hot enough to make tea), then a second try with a lot more water in the pot cooked the 2 eggs from 3pm until 6pm - the water was actually boiling when I opened it up.
I was quite surprised at just how seriously hot it could get.

If tomorrow is as good i'll try and be a bit more adventurous and try to cook a full meal. Anyone else up for the challenge?

mjv2ydratu679c

nigra wrote: »

What with the good weather and the need to keep young children occupied outdoors, I managed to boil 500mls of water for my first cup of tea from a DIY solar oven and then hard boil a couple of eggs without really trying in my back garden.

I glued kitchen foil to a cardboard IKEA box to make reflector panels. Then I put a water filled black pot inside a clipped oven bag, all under the glass dome of a cake dish and placed the reflector panels to concentrate the sunlight onto it. It took an hour initially from 1pm to heat the water (which turned out to be hot enough to make tea), then a second try with a lot more water in the pot cooked the 2 eggs from 3pm until 6pm - the water was actually boiling when I opened it up.
I was quite surprised at just how seriously hot it could get.

If tomorrow is as good i'll try and be a bit more adventurous and try to cook a full meal. Anyone else up for the challenge?

Hi that's seriously impressive, could you post up a few pics of your setup?

nigra

I'll put up some pics later once i figure out how!

It was a hell of a day again today so i put out a similar solar oven setup as yesterday but this time (as i was emboldened by yesterday's success) with new potatos/carrots/parsnips/onions. I put it out at 11am. Planning on taking the pot out at 5.30pm.

mjv2ydratu679c

nigra wrote: »

I'll put up some pics later once i figure out how!

It was a hell of a day again today so i put out a similar solar oven setup as yesterday but this time (as i was emboldened by yesterday's success) with new potatos/carrots/parsnips/onions. I put it out at 11am. Planning on taking the pot out at 5.30pm.

Will be interesting to see how you get on today, especially the potatoes

nigra

Another success today, the pictures which follow will tell the story better than i could. If anything the veg + spuds were a little overdone. It was a large quantity of food, enough for 4 people this time.
I'm quite amazed at just how easy this is!

mjv2ydratu679c

nigra wrote: »

Another success today, the pictures which follow will tell the story better than i could. If anything the veg + spuds were a little overdone. It was a large quantity of food, enough for 4 people this time.
I'm quite amazed at just how easy this is!

Must give it a go myself. When I see how you built yours I'll just copy it

nigra

nigra

If it can be done in west Dublin in May, there shouldn't be any reason anyone else can't do it!
If vegetables like carrots or parsnips can be cooked there really isn't going to be a problem with meat. As you can see my whole setup is quite flimsy really, i have a few ideas to make it a bit sturdier but as this is 'Survivalism and Self Sufficiency' i'm running with the cheap and cheerful philosophy for the moment. I left the pot out today from 11am until 6pm as i was worried about the veg being overdone. I didn't need to leave it out so long and cooking time could have been shortened by at least an hour.

The oven bag i got in Supervalu, the other materials were to hand and whatever little technical knowhow came from solarcooking.org

It looks like it will be another fine day tomorrow, i'll try chicken drumsticks or thighs. Anyone else going to give it a shot?

nigra

Its going to be another scorcher tomorrow. If anyone else feels the urge to give solar cooking a try then post some pics please...

mjv2ydratu679c

nigra wrote: »

The oven bag i got in Supervalu, the other materials were to hand and whatever little technical knowhow came from solarcooking.org

Fantastic job - seriously impressive

my3cents

nigra wrote: »

... but as this is 'Survivalism and Self Sufficiency' i'm running with the cheap and cheerful philosophy for the moment....

The Primus Litec kettle is a fairly serious bit of kit

nigra

Another nice sunny day. I tried putting chicken thighs into the pot this time around. I left them out at 12 midday when it was intermittently overcast and initially was resigned to failure, but as the evening turned out so well i needn't have worried. I used a similar setup to the last couple of days with one or two minor variations. I put the pot with the chicken into 2 oven bags this time, again all under the glass dome. I placed a few stones under the pot inside the bags to support it off the tinfoil reflector base. Both tricks are supposed to improve performance. I had to resite the whole oven setup once in order to better catch the sun. I finished up at 6.30pm and was relieved to find perfectly cooked chicken.
Apologies for the food porn which follows...









Anyway, i think the matter is settled. Also i don't want to keep posting food pictures here. You can easily make and successfully use a basic DIY solar oven in Ireland... in summertime. I take the point about the Primus Litec pot, but from what i've read any dark ,ideally metal and thinwalled, pot should do the trick. Now i just wish i had tried all this out last year during the heatwave.

Boardnashea

That's some great work nigra. Well done.

my3cents

nigra wrote: »

...I take the point about the Primus Litec pot, but from what i've read any dark ,ideally metal and thinwalled, pot should do the trick. Now i just wish i had tried all this out last year during the heatwave.

LOL I was just pulling your leg about the Litec pot. Surprised no one else noticed it. tbh it just shows that you are more prepared than the average Irish citizen

There are areas where you can get away with using everyday items and others where specialist equipment pays dividends.

At one level a heavy cast iron dutch oven is a good S&SS item and at the other extreme a lightweight Litec pot is what you need. I'd have both because I want to be able to have that choice in how I survive if the need arises, bug in or bug out.

A solar oven is just another of those options we do not have ideal conditions every day of the year but its another option when its sunny and very handy if fuel is in short supply. Another point is that a solar oven doesn't leave a footprint like a cooking fire does (smoke and the fireplace).

For me its not about having one answer its all about having as many options as possible.

Ditto - good work! Its one thing having an option its another to prove it works.

Kevhog1988

Small fella made one of these the other day after seeing it on rte home school hub.

GinSoaked

Kevhog1988 wrote: »

Small fella made one of these the other day after seeing it on rte home school hub.

So what did he cook with it?

Kevhog1988

GinSoaked wrote: »

So what did he cook with it?

just heated a small bottle of water so far.

GinSoaked

Kevhog1988 wrote: »

just heated a small bottle of water so far.

Thats a really good thing to try with because you can work out the amount of energy you are getting from the sun.

So you could compare different solar ovens efficiencies at different times of day etc.

To put an actual figure on the energy used the calculation is....
The specific heat capacity of water is 4,200 Joules per kilogram per degree Celsius (J/kg°C). This means that it takes 4,200 J to raise the temperature of 1 kg of water by 1°C. (https://www.bbc.co.uk/bitesize/guides/z2gjtv4/revision/5)

But really for comparison you'd just want to know how long it took a solar oven to raise say 100ml (100grams) of water by say 10 degrees.

Why would you do that - well its day 30+ of restrictions