solar cooking

I've been cooking with pure unmediated sunlight for 20+ years and would love to hear how the permaculture community is doing likewise  I have a non-monetized video series focused entirely on the many dedicated solar cooks who use, design, and promote solar cookers. Not selling any product, just the idea! youtube.com/@SolarCookingMuseum

My wife for several years made her Molly Baker Solar Oven. It was a very lucrative sideline for her. She has since moved on to other pursuits. Here is a review by one of her purchasers.  https://www.youtube.com/watch?v=KC7Ti3uh2Xs
I used it on many Kayak adventures and hunting trips during fire season when open flames were prohibited.

I use a simple cardboard box lined with aluminum foil with a foil reflector. Very simple. It easily gets right up to, but not quite boiling. I think with a few simple modifications it would easily boil water. We use it for any job that requires hot water. Sun tea, coffee, make yogurt in it, raise bread dough.

My wife generally preheats pans or pots of water before cooking on the stove. Greatly reduces time. We use it every non-rainy day spring summer and fall.

Luther Krueger wrote:I've been cooking with pure unmediated sunlight for 20+ years and would love to hear how the permaculture community is doing likewise  I have a non-monetized video series focused entirely on the many dedicated solar cooks who use, design, and promote solar cookers. Not selling any product, just the idea! youtube.com/@SolarCookingMuseum

Ha,  and I watch every video  

Hi Luther this is Mart from MeWe  now decommissioned group,  glad to see you here.     I just posted one of your videos here....

I so enjoy your interviews as there is a wealth of know how the people you interview have that is useful to know for those of us who like to cook or use solar in original ways.

I do enjoy your videos and recommend them to all who see the value of using the sun to our advantage.

Your video on using solar panels direct to a resisitive  loads  had been most helpful to me with my sand battery experiments.      

Thank you again!

I have had a solar oven for years.  I use it in the summer, as I use my fireplace in the winter, to offset my use of LP gas.  While I don’t use it daily …I live under frequently cloudy skies .. it does help.

Luther Krueger wrote:I've been cooking with pure unmediated sunlight for 20+ years ......

Luther,   Just finished the other night watching your conversation with Nate Hagens on solar cooking:  https://www.youtube.com/watch?v=AaLHkRRbbT4    I use the Solavore Sport which has been discontinued for many years, but appears to possibly be poised for a re-boot...?  This is good news to me as my old original has taken some bumps and bruises along the way and I hope I can get a new, clear top for it soon.  If not, I plan to just cut a 'to-fit' piece of twin-wall greenhouse glazing as a substitute. As with others who live under partially sunny skies most of the time, I use mine on the 'good days' and shortly will be adding a batch of cookies for an afternoon bake.  A favorite task for the stove is to fill the black pots that come with it with water and dry beans for a day-long cooking.  Truly set-it and forget-it for this kind of cooking.

My mom had one growing up, and I have one currently sitting under my house. Problem is the erratic weather in Hawaii kind of ruins the experience. If it stays sunny then the solar ovens do cook some delicious food but in Hawaii it's not uncommon for it to rain on and off again even on sunny days which significantly slows everything down.

Cooking with solar: my first impression of how this would work best was a solar panel, battery, and an instapot pressure cooker. Those things are so low wattage, intermittent power usage when up to pressure and temperature, that they'd be fast and efficient compared to reflector based ovens.

There are several groups that are working to distribute solar PV-to-induction or electric heating element cookers in Africa (SunSpotPV, ECOCA, MPISHI). My sense is they are running into unanticipated costs for what should be an appliance that would cost under US$300. When the sun is shining, parabolics and vacuum tube cookers cook just as fast as any fossil-fuel or electric cooker. Box cookers are as good or better than "crock pots" for slow cooking, and many panel cookers equal their cooking prowess. One needn't use them side-by side for comparison, e.g., I've often stir fried food in a 1.4 meter parabolic every bit as fast--and with far less need for fussing with dials--than my gas range. I have several guests' stories about both PV-direct cookers along with the standard fare of strictly thermal reflector/insulation cookers on youtube.com/@SolarCookingMuseum Recently I also posted the great work of Alexis Ziegler who's set up a whole community cooking system with strictly DC direct to heating element cooker at the Living Energy Farm in Virginia.

Joseph Bolton wrote:Cooking with solar: my first impression of how this would work best was a solar panel, battery, and an instapot pressure cooker. Those things are so low wattage, intermittent power usage when up to pressure and temperature, that they'd be fast and efficient compared to reflector based ovens.

Yes, the Ports, to whom the operations for the popular Sport model reverted after Solavore stepped out of the picture, hope to bring it back into production soon. I'd recommend going ahead and using greenhouse glazing, which I think would work very well. Glad you mentioned it, I have a few Sports (what with it being produced near my home town of Mpls) and one has a cracked window which sometimes feels more awkward to set up with the reflectors--and also I've gotten accustomted to only using the reflectors in the winter. Will see how I can make the reflectors that came with them attach to my scrap greenhouse glass--let me know how your plan works!

Luther Krueger wrote:I've been cooking with pure unmediated sunlight for 20+ years .....

John Weiland wrote:I use the Solavore Sport which has been discontinued for many years, but appears to possibly be poised for a re-boot...?...If not, I plan to just cut a 'to-fit' piece of twin-wall greenhouse glazing as a substitute. .

A solar electric system is about 20% efficient.

I’d guess a solar-thermal slow-cooker is probably 40-50% efficient.

An optimized higher temperature (commercial) design is around 65-75% efficient.

Happy to share my interview with Stephen Thomas, recorded in May for my solar cooking channel. I learned a ton from Stephen and especially excited to see the hybrid solar/wood-energized solar dryer. I just shared our visit also with facebook.com/@SCWNet, which I encourage fellow Permies to check out! https://youtu.be/OopjFimRG4c

Luther,

I think you would greatly enjoy this video.

This is a rabbit trail I knew nothing of, of how solar was used in times of old.

https://youtu.be/mz-iKEMWQKE


This guy does his homework.

Yes, that's the kind of thing that the book "A Golden Thread" talks about. It begs the question if so many people know how powerful the sun was, why didn't solar cooking become a routine thing? Like on history prof said, If the Romans could stamp out coins, why didn't the take it to the next step and make the printing press? We may never know!

Luther Krueger wrote:Yes, that's the kind of thing that the book "A Golden Thread" talks about. It begs the question if so many people know how powerful the sun was, why didn't solar cooking become a routine thing? Like on history prof said, If the Romans could stamp out coins, why didn't the take it to the next step and make the printing press? We may never know!

I believe because for a few pennies of electricity, or gas they can have the meal done 24 hours a day....

I believe solar panels + batteries  + a charge controller is the way to go as it gives you the power of the sun at about any time.        I am wondering why we don' use solar panels to distill alcohol and then have energy that will store for years?

Today I finished putting together this 1.5 M    ( 2 inches shorter than 5 feet )  solar cooker.

It is a beast....     I am impressed with the size and the price $85.00 delivered!   which blew me away.

What I liked about this one is it had all of the hardware to adjust  what needed it to work.

https://www.ebay.com/itm/166566234548?_skw=Portable+Solar+Oven+Cooker+1.5m+Diameter+Multi+Function+Camping+Outdoor+Stove&itmmeta=01J842TNFGW1MMAWXVVGKCSX0C&hash=item26c81f09b4:g:DM4AAOSwD2Vmmloq&itmprp=enc%3AAQAJAAABEHoV3kP08IDx%2BKZ9MfhVJKlkyCunQFEFVY9cxYwfYZUHeyJH8yC4rVZ%2FaUSBxauikCyMxZaD9XPQ7i7xXLcLhhQz45mDCn2rs7tmqvVgowTEsnXuaWFDjAX24CxfXLuBswM%2BIJbgwW66bmJL06GTFkMvInGY1e4%2BZJu8lvZGwck%2Fo%2Ba7Nmybo%2F2a2OaYQyHaI%2FAEn9nddyTwyl2LEhq0bMXpyRLpm6CRBLafC18BY%2BE2CdcuD9wfdBV9nVPnl6x1LViXIGE2kuTrSuWoYDEy3HW%2BNLOwgh63Yyd1rQatHFryMHwzXT3tc3KGSKpv33g7vTOGCSYKliJbI5s2n4CPJUF03ZUTOYh%2BjAaTOwU2B%2B3k%7Ctkp%3ABk9SR-rX6oLBZA

Lesson learned....   the solar cooker is more powerful than I thought.     While I was cooking I heard a ping sound with my cast iron pan.        It cracked the cast iron pan!    heat was so intense the pan  my dear grizzwall  is now  experimental material.......       But it makes me happy that  there is that much power there.     so...  my next plan is to use this grizwall on the solar cooker with sand in it, about 1/2 inch, then I will put another cast iron pan on top of this which I will try to cook in..    because there is that much heat there should give me a medium burner cooking and much more even cooking.     Farwell  grizwall pan..

Mart Hale wrote:Lesson learned....   the solar cooker is more powerful than I thought.     ....  It cracked the cast iron pan!    heat was so intense

Woah, that is impressive! (and sad)
I suspect that the pan had some stresses in that some differential heating made worse....That can happen going to temperature extremes quickly. Solar cooking is not something I'm prepared to invest in here - just not worth it for the few days we'd get enough sun. The last 2 or 3 may have been good enough though!

Nancy Reading wrote:

Mart Hale wrote:Lesson learned....   the solar cooker is more powerful than I thought.     ....  It cracked the cast iron pan!    heat was so intense

Woah, that is impressive! (and sad)
I suspect that the pan had some stresses in that some differential heating made worse....That can happen going to temperature extremes quickly. Solar cooking is not something I'm prepared to invest in here - just not worth it for the few days we'd get enough sun. The last 2 or 3 may have been good enough though!

Yeah, I did some temp readings.     Once section of the skillet was over 400 deg   about 2 inches over it was 200 deg.      

To mitgate this I put in 2 inches of sand  with a lid..       when I lifted the lid sand was about 200 degrees...       all over top,   I then went to 1 inch of sand temp was consistent a little over 300 deg...      I put a tea kettle on top of the sand just to see how that would do.       The water is climbing up rapidly.     Good heat transfer through the sand...and I can regulate the temp by depth of sand..

I understand about the sunshine or lack of...    I used to live in Indiana, and this motivated me to move to Florida ...

I have a tracking solar cooker project that made good progress this year.  Its experimental,  I'm trying to expand the reach of solar cooking so I don't cook food in it.
Instead, in a "play to get gardeners interested" I steam soil and I make weed soup instead of compost and compost tea.  

Because I didn't know how good my new tracking system would be,  I didn't go with a standard parabolic dish, instead going for something with a deeper curve, that doesn't concentrate the light as much, ( but the bonus is that it still concentrates well even if it isn't accurately aimed, plus it is less likely to hurt your eyes if it misses the target).

 My tracking system was bulky at the start,  now it's a lot smaller.  And the latest version is a bit "steam punk". Its mostly made of wood, and  It has  a miniwaterwheel that "winches" the solar reflector around!
There are no electronics outside.  It is all run on compressed air that comes from a pond air bubbler. It's a "time based tracker". The gradually increasing air pressure over the day in one pipe tells it where to point.    

So, results?  Are they good?
I steam soil in 7 liter batches,  it cooks or simmers  the whole day. 7 liters of soil with one liter of water added to prevent the soil burning.    I used it first to grow seedlings (no weeds) so they have no competition. They "seem" to do better.  The real test was accidental.  I was planning a planter with just solar cooked soil over a layer of solar cooked weeds.  BUT, I ran out of solar cooked soil half way.  So, I just used ordinary soil for the rest.  WHAT    A    DIFFERENCE!
(In fairness I transplanted lettuce into the non cooked soil one day later than into the solar cooked). In the solar cooked soil, the lettuce is significantly bigger and a darker green.  And there is an explanation.   The weed seeds, bulbs, stolons and tiny bugs, and bacteria have been cooked and they have released their juices into the soil.  New bacteria quickly colonized it and converted a lot of this stuff into plant food.  And the plants, without pathogens or soil insects eating their roots and making them sick, grew faster.
   
Weed soup is the 7 liter pot packed with chopped weeds, tamped down and water added to the top.  Put on the solar cooker,  and track for the day,  If it gets to about 80 C its good enough.  (Usually gets to over 90 and simmers most of the day if its sunny).     I use the soup water at about one in 20 in my watering can like compost tea.  Seems to have given my beans a big boost.  (It's carbohydrate and nutrients for the soil bacteria).  Probably helped the other plants too.   I have used the dry part of the cooked weeds mostly as mulch.  It rots down really fast,  and the worms seem to love it.  
Advantages?  I can use tomato clippings back on tomatoes, (because they are cooked).  Blackberry smells like strong rose perfume when it is cooked,  fennel smells great too, and even my mulch has a great scent when I put it on.  And instead of waiting 3 months to get the value out of compost,  I get the weed nutrients the very next day,  plus the carbohydrates can work right there in the soil to boost plant growth immediately, (instead of just doing rotting in the compost heap.   I am putting in a link to a playlist,  because it is a big project.  
The beauty of this system is that you reset it every evening,  and put the next batch on (if it wasn't cloudy all day)  and  you can safely ignore it all day till next evening.  Here is the playlist https://www.youtube.com/playlist?list=PLkzXlmAwZTZdwFHYgD8mp4RFg2-Ap-ZNy and here is one of the vids in case the playlist link doesn't work https://youtu.be/IKMkPy4kkTY