Solar Cooking

There is nothing difficult about cooking with solar energy. A cardboard carton and a sheet of glass will do the trick. This document is in two parts:-

(1) A first trial of cooking rice in a cardboard carton

(2) A series of enhancements to the initial system - faster cooking, bigger dishes, and so on.

I encourage you to try cooking a small bowl of rice in a carton. Either that, or dry some vegetables or fruit. Then you will know by your experience that this can be done.

Cooking Rice

A cardboard carton, a dessert bowl, rice, water, and a sheet of glass that covers the bowl.

(1st) Use a regular dessert bowl from your kitchen. The aim here is to cook a ½-cup of rice into an amount that could be used later today as a bed for a meat sauce or for a vegetable dish.

The size of the bowl will determine the size of your carton. You want a carton that can hold the bowl, but only just. We will cut the carton down vertically to a size where it is tall enough to hold the bowl with a bit of air-space on top. The idea is to have the sun's rays fall directly onto the bowl, and heat the contents of the bowl, but not have to heat too many gallons of air.

(2nd) Find a clean cardboard carton and cut it down, glue it together if necessary, to make a container that leaves about one-inch of wall on each side above the bowl.

Don't worry too much about the size. If you have a carton that leaves about two inches of space, then use that for this first trial; don't spend half the day making a carton.

(3rd) Use a clean sheet of glass. An old window pane works well, as does the glass from a picture frame.

Clean the glass (a) so that no bits of grit or fluff fall into your rice and (b) so that the sun's rays can pass unobstructed through the glass.

(4th) Same old drill: half a cup of rice and one cup of water into the bowl.

Place the bowl in the carton and the carton where it will receive sunshine for most of the day. You want a spot where curious pets, children, and raccoons will not venture.

If there is even the slightest breeze, place house-bricks around the base of the carton. We do not want to waste a day of trial by the carton tipping over partway through.

(5th) Crank up your patience. If this is a good day to be away from home all day, so much the better.

Avoid the temptation of "lifting the lid" every fifteen minutes to see how things are getting on.

(6th) Maintain a log or diary; record the time when you set the bowl in the carton, whether there is partial cloud, and the time you sampled the rice.

Rice is fairly cheap, so be prepared to toss a few trials on the compost heap!

My bowl, bracketed by a cup of water and a half-cup of rice.

The bunch of bananas ($0.99 at Foodland yesterday) suggests that I might try drying slices at the same time.

My cut-down carton, cut down to height. Because I was too lazy to trim it to length, it can accommodate a plate of sliced banana as well as a bowl of rice.

I might regret drying banana; how can banana dry out when rice is boiling? Heigh-ho! If I end up with only softened rice and soggy banana, I have tomorrow to try again.

The carton is sitting on a thick scrap of timber to heat-insulate it from the damp grass.

Four half house-bricks serve as simple wind guards.

And here is one of my old sliding-window panes, newly hosed down on both sides.

This is the thickest cloud I could see at eight o'clock this morning.

And here, almost overhead, is the thinnest cloud. These clouds might well burn off within the hour.

The solar cooker is sitting where it is about to receive full sunlight, since I severely lopped my aspen trees two months ago.

My image-loading system is accustomed to identifying each photograph with a date and time stamp, so the image name itself serves as a record of time.

You can't see the image name, so I will tell you that I set out the empty bowl at 07:58 and took the photos of the clouds at 08:11. This trial took me ten minutes to set up.

Have at it!

By 11:30 decent-size drops of water have condensed under the glass pane.

I decide to slip the banana slices outside; my goal is to have edible rice by 17:00. The banana can take its chances air-drying under glass outside the box.

But as I type this up I think that the other half of the carton could be a second box that fits under the pane, with a very small gap to allow vapor to escape from the banana box.

This is why I find a Second Use For Everything: The second part of the trimmed down carton is perfect for making a second carton for the drying oven. Had I tossed that cardboard into the bin I would be searching for another carton.

The banana carton has the glass propped open with a stick.

The stick makes a gap of just under one centimetre, plenty of room for molecules of water vapor to escape (there are, I believe, three thousand billion molecules of water per cubic millimetre.

By 13:00 the glass above the banana is clear, while the glass above the rice shows condensed moisture.

By 15:30 six people have sampled the rice. To my mind it is perfectly cooked, steamed rice, separate kernels, light. I had planned to eat Cod Tongues at Skippers tonight, but a thunderstorm sweeps across town, so I eat steamed rice for supper instead.

Two days in the refrigerator (bad weather) then out go the fish at 09:00 on Friday.

Enhancements

This section is incomplete; the paragraphs are placeholders for ideas I have stolen from other web sites, or thoughts that popped into my head.

(1) Research drying tips. For example, lemon juice to inhibit "browning" of banana chips..

(2) Use a wooden box with carrying handles.

(3) Purchase a thermometer to record heat throughout the day.

(4) Use a polystyrene foam container as the cooking oven.

(5) A recessed (flanged) oven container that provides a snug air-tight fit for the glass. My thought here is that as hot air escapes, it takes with it the heat required for cooking.

(6) Back, and also side-flaps that can augment solar rays without moving the box. The flaps should be covered with reflective material such as aluminium foil; glass mirrors cut to size would work, but would add weight.

(7) Add reflective material to the interior walls and floor of the cooking oven.

(8) Consider using muffin-trays to cook rice in smaller volumes, thereby increasing its cooking-surface area.

(9) Coaster beneath the bowl or pot to avoid melting or charring your cooking oven.

(10) Pre-soak rice the night before.

(11) This method of cooking takes time, but it is difficult to over-cook your food. You have no need to check "boiling over" every fifteen minutes; worst-case you have to finish cooking the food indoors.

(12) The set of foodstuffs that can be dried is not endless, but apple, pear, and banana, are readily available in the stores here, year round. Fish, especially capelin.

(13) This day I have four window panes available. Three more windows will be extracted over the next few months, which means I will have sixteen panes available. Hat is a fair-sized drying farm!

(14) Baking bread or cakes

(15) Drying fish

(16) Re-caking shoe polish in tins.

(17) Drying pairs of socks that caught a mild rain shower.

Calculations

The glass area of each unit is 21"x30".

With sixteen panels I could make a drying array either 28 feet long or 17.5 feet long.

Either way I get thirty square feet of glass.

That is a lot of dried banana chips in one day.

By the same token it is a lot of ground-level forcing covers to accelerate growth in the early spring.

Drying Fish

On Saturday my neighbour went out for Fish; in Newfoundland "fish" means "cod", everything else is bait.

I strip the carcasses (which are now buried deep in my compost bins) and reclaim about fifteen pounds of flesh.

I Made twelve packets of large flakes, twelve packets each of two smaller flakes, six packets of small pieces, and three bags of scraps - which I will use to make chowder.

Here they are, bagged and heading for my freezer.

I extracted a dozen or so strips of flesh which would have gone into the chowder-bags, but will this day be used as an experiment in drying.

The two side-plates weigh 11 ounces.

The two side-plates with fish strips weigh 1 pound 5 ounces, so I have ten ounces of fish flesh at 10:00

The two plates go into the carton where yesterday I made steamed rice.

At this time I have not looked up "How to dry fish"; I am still interested only in the basics - do I generate enough heat to dry the fish, that is, to boil off much of its moisture content?

Yesterday's banana chips enter their second day of desiccation, we hope.

I took the fish in after a second day (Friday, July 22, 2022) and insects were present under the glass. I weighed them and then stored them in a screw-top Jar to see if grubs hatched.

Sunday, July 24, 2022

11:00 bowl with ½ cup brown rice (not soaked overnight) and 1 cup water.

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