Solar Cooking in the UK?

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Toadflax

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Mar 26, 2007
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Has anybody here tried solar cooking in the UK? Have you had any success?

I've just been given a solar cooker (one of these http://solarcooking.wikia.com/wiki/HotPot) but, looking out of the window at the cloudy sky, I think it may be a while before I can try it out. :(

Would be good to try it at the Moot, but with all those trees...and Welsh rain!


Geoff
 
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Toadflax

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Totaly unrelated to the subject of the thread, but a Google must index new stuff very fast. A search on "solar cooking in the UK" less than 30 minutes after the original message was posted comes up with this thread.


Geoff
 

Toadflax

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With a bright sunny day, I had a chance to try out the Hot Pot solar cooker I was given a couple of weeks ago. It's not something I would have bought, given the British weather, but something that looked interesting to experiment with.

It has been designed primarily for countries that are sun-rich, but fuel-poor, and where the primary cooking fuel is wood. The supporting documentation suggests that (primarily) women can spend two days a week gathering cooking fuel and that solar cooking, where it is effective, can therefore release them to work on other cash earning projects.

As you can see from the picture, it comprises a black enamelled cooking pot (black body absorption of heat), which sits suspended in a glass bowl with lid (greenhouse effect)...



...and the whole thing sits inside a shiny reflector 'dome', so directing further sunlight all around the cooking pot.



I didn't expect good results on a Winter's day in England, but was impressed with the heating that I did get on a bright sunny day. It certainly gave me optimism that it might work in a British Summer, on the right day, but most definitely not something on which any reliance could be placed.

I put one pint of water in the cooking bowl, with a thermometer left in it, and took readings throughout the day. The ambient temperature remained at a constant 5degC all day, and the water temperature (from the kitchen tap) started out at 10degC. This is a graph of the readings, with a peak of 64degC at about 2pm. At this time you could see bubbles starting to form at the base of the cooking pot, and curls of steam rising from the surface of the water.



Whilst this would be a long time to wait for a cup of tea, I can see that it may be possible to cook later in the year. With an ambient temperature that could be 15+ degrees higher at the height of Summer and the sun much higher in the sky, I'm hopeful that it may get to boiling point, given the 60degC rise above ambient that it achieved in Winter.

Anyway, more to follow as I try it out later in the year.


Geoff
 

dwardo

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Aug 30, 2006
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Looks interesting and considering the 5 deg C ambient it did pretty well.

Will be interesting when the weather is a little warmer..
 

IanM

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Oct 11, 2004
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I tried it last summer on the hottest, longest day, blastingly hot. 29 June, 30.6°C @ 51° 27" North.

I made a tinfoil and cardboard reflector similar to but about 20% larger than the one above. The target was a 2 litre aluminium pan painted black with radiator paint placed inside an oven bag and resting on a 1cm cork mat insulator. In the pan was one litre of water and 50g of rice to cook.

The reflector was kept facing the sun by adjusting every 20 minutes or so.

The water finally, after a couple of hours was too hot to put a finger in (60C+) but never boiled. After another three hours (11-14:00) I broke it down and had lunch.

The rice was still not cooked enough to eat.

Fail.

Don't forget to wear very good sunglasses or in my case welders goggles, it is BRIGHT.
 
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Toadflax

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Ian

That's interesting information. I saw your earlier posting. :)

I'm hoping that a design that has evidently gone through a number of design refinements will be reasonably efficient.

As I said, it was a freebie for me, so it's worthwhile playing with, but I wouldn't otherwise have even thought of trying it in the UK.

I'll let you know how I get on with in the Summer.


Geoff
 

IanM

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Oct 11, 2004
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Please let me know even by PM, I am seriously interested for professional reasons. I just can't find any real world tests of these cookers.

I strongly suggest a practical test such as my 50gm of rice cooking, it brings the whole thing into reality with feet on the ground.

PS Have a look at:

http://www.solarcooking.org/asae_test_std.pdf
 
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Toadflax

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Mar 26, 2007
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Please let me know even by PM, I am seriously interested for professional reasons.
I will do. I'm certainly going to keep trying throughout the year and I'm happy to give it a go with your rice test, though it won't be under seriously controlled conditions.

I've glanced at the PDF doc, but will have a proper read through another time.


Geoff
 

Toadflax

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Mar 26, 2007
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An update on a much warmer day than last time, though still didn't quite get to boiling.

With a much warmer day (20 degC ambient) the water temperature got up to a maximum of 87 degC, and held close to that level for a reasonable period of time. I'm not sure whether 80 degC is sufficient to cook food (e.g. meat) but if I continue to get some good days, I'll certainly have an attempt at cooking some rice.






Geoff
 
you can cook meat (some ) as low ans 55 deg but it needs a long time ot get the heat thru (Heston BlominHeck did a whole animal in a Jaccusi turned right up but it took all night

its also hot enough sterilise water as apparntly you only need raise it to 77deg and hold for 20mins or hotter for shorter etc

ATB

Duncan
 

Glen

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Oct 16, 2005
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I beleive if you were trying to make jerky 80 degC would be considered cooking rather than drying.

I'd be interested to see updates throughout the year, if you've got the time and inclination to do them.
 

spiritwalker

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Jun 22, 2009
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apart from poor people in africa or similar places i cant see a need for one? in this country it would be useless to lug something that size about camp when surrounded by trees or other sources of fuel. But for desert or really hot areas it might be viable but i guess those people could never afford one or probably hear about it?
 

Toddy

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Jan 21, 2005
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True, true, but it is the sort of thing that could be included in emergency aid packages for tropical countries.

I wonder whether it would give results equivalent to our slow cookers, and if instead of rice, which really does need at least an initial boil to cook properly, it would work with legumes like lentils, or quinoa, or steamed lentil cakes like idli ??
It would certainly cook porage (whether oats, sorghum, millet or gari )at those temperatures; slowly, but it would cook, and I suspect that root vegetables, like potatoes, yam, taro, etc., too would cook in hot, even if not boiling water.

Interested to hear how it goes with greater sunshine here in the UK.

Thanks for the post.

cheers,
Mary
 

Toadflax

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Mar 26, 2007
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apart from poor people in africa or similar places i cant see a need for one? in this country it would be useless to lug something that size about camp when surrounded by trees or other sources of fuel. But for desert or really hot areas it might be viable but i guess those people could never afford one or probably hear about it?
As noted earlier in this thread, these have been designed for the equatorial regions, with sales to people in the better off nations being used to subsidise the sale to the people who can benefit most from them, and to promote their use in such areas. More details can be found here: http://www.she-inc.org/hotpot.php

A number of my colleagues work in such areas, and I was fortunate enough to be given one to try out in the UK.

Geoff :)
 

Glen

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Oct 16, 2005
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You can actually get hybrid Solar/electric cookers, at least for 120v supplies.

I guess the idea behind those is that you can rely on a temperature and hence cooking times.
 

Toadflax

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Mar 26, 2007
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On the first really good day that I had spare (i.e. at a weekend) I tried cooking some rice, 2 pints of water with 2.5 oz (i.e. one portion) of rice, and the results are very encouraging.

It certainly looks like this cooker would be a very viable cooking method given the right weather conditions (i.e. not a reliable method for the high temperate regions except on cloudless days). It didn't boil, but with the time period for which it held a very high temperature, it would appear that stew type meals could be cooked in a similar way to a slow cooker. The temperature started dropping after 15:00, but was still at about 80 degC by 4pm. The rice was disintegrating by 12:30.




Geoff
 

Mikey P

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Nov 22, 2003
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With a bright sunny day, I had a chance to try out the Hot Pot solar cooker I was given a couple of weeks ago. It's not something I would have bought, given the British weather, but something that looked interesting to experiment with.

It has been designed primarily for countries that are sun-rich, but fuel-poor, and where the primary cooking fuel is wood. The supporting documentation suggests that (primarily) women can spend two days a week gathering cooking fuel and that solar cooking, where it is effective, can therefore release them to work on other cash earning projects.

Geoff
Geoff,

There's an excellent section in Cody Lundin's book, 'When All Hell Breaks Loose' about solar ovens. I'd really thought much about it until I read a few pages of the book and it really makes sense. It's good to see that it works even here in the UK, but when you think about how much fuel it would save in developing countries...