Help with Solar Oven article by sci

The Solar Cookers International has an article (in pdf), "Solar Baking Under the Sonoran Sun" by Laurie Stone, in which describes the building of a big solar oven. As the article was written in 1997 I have some questions about the construction of the oven.
1. I do not think the high temperature for the oven was given and I would like to know if the solar oven reached 400 degrees or above. If the solar oven does not reach 400 degrees what could be done in it's construction so that it would reach the 400 degrees.
2. The article mentions using Everbrite for the reflectors. Are glass mirrors better for reflectors than the Everbrite. Since 1997 are there newer materials that would make better reflectors than the Everbrite?
3. The article says that 3/4 inch plywood was used in constructing the solar oven's frame. Would a higher cooking temperature be obtained if the frame was built more like a box solar cooker in that one frame construction is constructed and then another one constructed about 2 or 3 inches bigger than the first one which would sit inside the second one which is about 2 or 3 inches bigger?
4. The article mentions using PV fans (I think these are solar cells to run the fans) -"The fans are run by a 6 Volt, 5 Amp module." - if these are solar cell powered fans information on the types of solar cells to use and the type of fans. And do you run the fans on all the different types of meals or just the cookies and pasteries - how about bread
A few questions about cooking with the solar oven described in the article.
1. Can a 16 inch pizza be cooked with the solar oven?
2. Can frozen foods be cooked with the solar oven such as: frozen pot pies - like Banquet and other type brands. Frozen TV type dinners. frozen fish breaded portions - like Gorton's and other types of brands. Frozen pizzas. Frozen egg rolls. Frozen Boritoes. Frozen fries like oreda fries.
3. Breads - sence the sun comes in through the glass do you move the bread after it has cooked for so long so the backside of the bread gets some sun
Thanks

sgotr wrote:

The Solar Cookers International has an article (in pdf), "Solar Baking Under the Sonoran Sun" by Laurie Stone, in which describes the building of a big solar oven. As the article was written in 1997 I have some questions about the construction of the oven.

You might do better to direct your questions to Solar Cookers International. info@solarcookers.org or http://solarcookers.org/
That said, I think I can offer some insight.

1. I do not think the high temperature for the oven was given and I would like to know if the solar oven reached 400 degrees or above. If the solar oven does not reach 400 degrees what could be done in it's construction so that it would reach the 400 degrees.

I think it's unlikely that the oven reached 400F. It's more likely that their design would run between 250F to 300F. This is, I assure you, quite hot enough to bake. It just takes a little longer than at higher temperatures.

2. The article mentions using Everbrite for the reflectors. Are glass mirrors better for reflectors than the Everbrite. Since 1997 are there newer materials that would make better reflectors than the Everbrite?

Glass is heavy and prone to breakage, not to mention being rather expensive. I've used reflective mylar to good success (much better than aluminum foil) but it does degrade over time and needs to be replaced every year or so.
This article describes using Anocoil Aluminum sheeting. http://www.sunspot.org.uk/Prototypes.htm

3. The article says that 3/4 inch plywood was used in constructing the solar oven's frame. Would a higher cooking temperature be obtained if the frame was built more like a box solar cooker in that one frame construction is constructed and then another one constructed about 2 or 3 inches bigger than the first one which would sit inside the second one which is about 2 or 3 inches bigger?

The article says that they used 3/4 plywood and ductboard insulation on the inside surface. This insulation is a fiberglass board type that is used to insulate air ducts in HVAC systems and typically runs around R6. This is more than enough for a solar oven with an R1 glass cover.
If you want to make it slightly better then you can double pane the glass cover. Adding a tracker to keep it pointed at the sun will help a lot as well. Adding more insulation could help but not a huge amount. Ductboard is pretty cheap though so it's not a major expense.
This fellow has some good ideas on trackers. http://www.redrok.com/main.htm

4. The article mentions using PV fans (I think these are solar cells to run the fans) -"The fans are run by a 6 Volt, 5 Amp module." - if these are solar cell powered fans information on the types of solar cells to use and the type of fans. And do you run the fans on all the different types of meals or just the cookies and pasteries - how about bread

Hmm, 6 Volts at 5 amps is a 30 watt solar PV panel. Seems rather excessive for a simple circulating fan. Either that's a typo or they're circulating one heck of a lot of air. You can probably do quite well with a 2 or 3 watt 12V solar PV panel running a couple computer style muffin fans. Any 12V PV panel would suffice to run 12V DC fans. You might want to find fans that don't produce toxic smoke when baked and that don't mind the temperatures inside an oven. I haven't tried baking any DC fans so I can't say how well they work.
The idea with the fans is that they circulate the air inside the oven so the temperature is even throughout. This means that parts of the oven that don't actually have something sitting absorbing the sunlight are still contributing by heating the air. I would think it would improve the performance of the cooker for most any cooking.
You can, of course, use mains power or rechargeable batteries to run the fans.

1. Can a 16 inch pizza be cooked with the solar oven?

Yes, assuming you have a 16 inch (or larger) solar oven that you can physically fit the 16 inch pizza inside.

2. Can frozen foods be cooked with the solar oven such as: frozen pot pies - like Banquet and other type brands. Frozen TV type dinners. frozen fish breaded portions - like Gorton's and other types of brands. Frozen pizzas. Frozen egg rolls. Frozen Boritoes. Frozen fries like oreda fries.

Yes. Typically it takes roughly twice as long to cook things in a solar oven than an ordinary oven due to the solar oven having a lower temperature.

3. Breads - sence the sun comes in through the glass do you move the bread after it has cooked for so long so the backside of the bread gets some sun

The entire inside of the oven is at roughly the same temperature, even more so with circulating fans, so spinning the food isn't required.
You might find the following links of use. http://www.solarcooking.org/ http://www.solarcooking.org/plans.htm http://www.solarcooking.org/docs.htm
Solar cookers, How to make, use and enjoy. http://www.solarcooking.org/Plans.pdf
Anthony

sgotr wrote:

The Solar Cookers International has an article (in pdf), "Solar Baking Under the Sonoran Sun" by Laurie Stone, in which describes the building of a big solar oven. As the article was written in 1997 I have some questions about the construction of the oven.

No link, no article seen, so general info only

1. I do not think the high temperature for the oven was given and I would like to know if the solar oven reached 400 degrees or above. If the solar oven does not reach 400 degrees what could be done in it's construction so that it would reach the 400 degrees.

I dont know what 400 is, usually they reach about 160C, but they can be made to reach whatever design temp is required. For higher temps you need more concentration, double glazing, and cavity materials that can withstand the temps used, ie metal rather than wood or card.

2. The article mentions using Everbrite for the reflectors. Are glass mirrors better for reflectors than the Everbrite. Since 1997 are there newer materials that would make better reflectors than the Everbrite?

You dont need 'better' reflectors. If its for mobile use, glass is the worst option.

3. The article says that 3/4 inch plywood was used in constructing the solar oven's frame. Would a higher cooking temperature be obtained if the frame was built more like a box solar cooker in that one frame construction is constructed and then another one constructed about 2 or 3 inches bigger than the first one which would sit inside the second one which is about 2 or 3 inches bigger?

thats a cheap way to insulate things. No idea about your oven plans though. Filling that cavity with fibreglass or rockwool really helps too.

4. The article mentions using PV fans (I think these are solar cells to run the fans) -"The fans are run by a 6 Volt, 5 Amp module." - if these are solar cell powered fans information on the types of solar cells to use and the type of fans.

6v 0.5A, and 6v 0.5A. The fan needs to be a high temp type though, any room temp fan would quickly fry itself. These can be rescued from dead fan ovens or combi cookers. Those would be mains voltage ac only fans. Naturally it doesnt matter whenther you use 3v, 6v, 12v, 240v, whatever, as long as you give the fan what it needs.
'5A' is a typo.
If for some reason you wanted to run a mains fan off a solar cell, either invert the cell output or rewind the motor for lower voltage and add a chopper so it sees a.c.

And do you run the fans on all the different types of meals or just the cookies and pasteries - how about bread

a fan moves heat from the hotspots to the cooler areas. Without it you get uneven heating and possibly even charring on one side. Always use the fan for best results.

A few questions about cooking with the solar oven described in the article.
1. Can a 16 inch pizza be cooked with the solar oven?

Havent seen the oven, but why not.

2. Can frozen foods be cooked with the solar oven such as: frozen pot pies - like Banquet and other type brands. Frozen TV type dinners. frozen fish breaded portions - like Gorton's and other types of brands. Frozen pizzas. Frozen egg rolls. Frozen Boritoes. Frozen fries like oreda fries.

why not.
The only gotcha is fries need very high temps to be best quality, and most solar ovens dont get that hot. The ovens I've seen typically do around 160C. This will cook anything, though its not quite the ideal nearly-universal temp of 180C, so cooking often takes longer at 160. Fries like 220C best, though will cook at any temp.
If I were making a solar oven, I would definitely make a little extra effort to get it running at 180C. Double glaze the front, use a metal liner with glass fibre insulation, and incorporate a thermometer so you can always see exactly what you've got. It takes the keep-checking element out of cooking.
To get best results from chips/fries in a 180 oven, perhaps put them all in direct sun and turn the fan off. You would need to move them part way through cooking then. That should get you top results.

3. Breads - sence the sun comes in through the glass do you move the bread after it has cooked for so long so the backside of the bread gets some sun

only if you find the oven has an uneven heating problem. The fan is meant to prevent that.
NT

Anthony Matonak wrote:

1. Can a 16 inch pizza be cooked with the solar oven?
Yes, assuming you have a 16 inch (or larger) solar oven that you can physically fit the 16 inch pizza inside.

Qualifier - You'll probably find that thin crust and regular crust pizza will be unacceptably soggy unless the crust was pre-baked, and that the cheese will not brown. It'll be edible, but not much more.
Some of the best pizzas are cooked at above 400 degrees F. to give the outer layer of the crust a distinct crispness. Many foods benefit from slower cooking. Pizza isn't one of them.
I did see one design for a solar oven that focused the light on the bottom of the oven, allowing good insulation where it counts. An oven like that, with a flat cooking stone inside to provide thermal mass, might do a decent job at cooking a pizza, but as I recall the oven had to be constantly moved to track the sun.

I found the link for the article it's here in pdf
http://www.solarenergy.org/resources/docs/stone_hp59.pdf
and I'm thinking of building it about half the 72" size
ok do not use mirrors lol
Reading the information posted thanks

Anthony
"The article says that they used 3/4 plywood and ductboard insulation on the inside surface. This insulation is a fiberglass board type that is used to insulate air ducts in HVAC systems and typically runs around
R6. This is more than enough for a solar oven with an R1 glass cover. "
If the solar oven can be improved to around 400 degrre + do you know if the ductboard would work for the insulation?
"You can probably do quite well with a 2 or 3 watt 12V solar PV panel"
Question on the PV panel in general - most that I have read about PV is that you use a battery which the PV charges the battery - can they be used to directly run the fans - if so more info on it please

2. Can frozen foods be cooked with the solar oven such as: frozen pot pies - like Banquet and other type brands. Frozen TV type dinners. frozen fish breaded portions - like Gorton's and other types of brands. Frozen pizzas. Frozen egg rolls. Frozen Boritoes. Frozen fries like oreda fries.

"Yes. Typically it takes roughly twice as long to cook things in a solar oven than an ordinary oven due to the solar oven having a lower temperature."
Does the crust brown?
"Solar cookers, How to make, use and enjoy. http://www.solarcooking.org/Plans.pdf "
for some reason the one in the pdf article is not listed there that I could fine


NT
"No link, no article seen, so general info only" Thanks read that and posted a link to the pdf article

4. The article mentions using PV fans (I think these are solar cells to run the fans) -"The fans are run by a 6 Volt, 5 Amp module." - if these are solar cell powered fans information on the types of solar cells to use and the type of fans.

"6v 0.5A, and 6v 0.5A. The fan needs to be a high temp type though, any
room temp fan would quickly fry itself. These can be rescued from dead fan ovens or combi cookers. Those would be mains voltage ac only fans. Naturally it doesnt matter whenther you use 3v, 6v, 12v, 240v, whatever, as long as you give the fan what it needs." "If for some reason you wanted to run a mains fan off a solar cell, either invert the cell output or rewind the motor for lower voltage and
add a chopper so it sees a.c."
Thanks
"The only gotcha is fries need very high temps to be best quality, and most solar ovens dont get that hot. The ovens I've seen typically do around 160C. This will cook anything, though its not quite the ideal nearly-universal temp of 180C, so cooking often takes longer at 160. Fries like 220C best, though will cook at any temp." "If I were making a solar oven, I would definitely make a little extra effort to get it running at 180C. Double glaze the front, use a metal liner with glass fibre insulation, and incorporate a thermometer so you
can always see exactly what you've got. It takes the keep-checking element out of cooking."
what is 220c in degrees?

Harry
on pizza "Qualifier - You'll probably find that thin crust and regular crust pizza will be unacceptably soggy unless the crust was pre-baked, and that the cheese will not brown. It'll be edible, but not much more." Would fresh made pizza work?

I have been doing some research and found these two links Temperature of a Home Oven (f and c and gas mark) http://hypertextbook.com/facts/2005/JenniferZhong.shtml Temperature of a Pizza Oven (f and c) http://hypertextbook.com/facts/2003/SaraElzeftawy.shtml
If the information is correct there the solar oven 400 f would be 205 c and for the pizza 480 - 515 f would be 250 - 280 c

sgotr wrote:

Anthony
"The article says that they used 3/4 plywood and ductboard insulation on the inside surface. This insulation is a fiberglass board type that is used to insulate air ducts in HVAC systems and typically runs around
R6. This is more than enough for a solar oven with an R1 glass cover. "
If the solar oven can be improved to around 400 degrre + do you know if the ductboard would work for the insulation?

This was already explained, as was how to get higher temp.

"You can probably do quite well with a 2 or 3 watt 12V solar PV panel"
Question on the PV panel in general - most that I have read about PV is that you use a battery which the PV charges the battery - can they be used to directly run the fans - if so more info on it please

panel runs fan, no battery involved.

2. Can frozen foods be cooked with the solar oven such as: frozen pot pies - like Banquet and other type brands. Frozen TV type dinners. frozen fish breaded portions - like Gorton's and other types of brands. Frozen pizzas. Frozen egg rolls. Frozen Boritoes. Frozen fries like oreda fries.
"Yes. Typically it takes roughly twice as long to cook things in a solar oven than an ordinary oven due to the solar oven having a lower temperature."
Does the crust brown?

no it goes green.

"The only gotcha is fries need very high temps to be best quality, and most solar ovens dont get that hot. The ovens I've seen typically do around 160C. This will cook anything, though its not quite the ideal nearly-universal temp of 180C, so cooking often takes longer at 160. Fries like 220C best, though will cook at any temp." "If I were making a solar oven, I would definitely make a little extra effort to get it running at 180C. Double glaze the front, use a metal liner with glass fibre insulation, and incorporate a thermometer so you can always see exactly what you've got. It takes the keep-checking element out of cooking."
what is 220c in degrees?

Its 220 degrees centigrade.

on pizza "Qualifier - You'll probably find that thin crust and regular crust pizza will be unacceptably soggy unless the crust was pre-baked, and that the cheese will not brown. It'll be edible, but not much more." Would fresh made pizza work?

Sometimes I cook pizza at 180 and it still comes out good.
Build one, if possible with double glazing.
NT