Por Kirk Jackman.

In this fourth article about easy ways to use solar energy we will further explore Solar Heat Harvesting and how we can use it for our benefit.

This series of articles focus on the direct use of Solar Heat Energy for household Heat applications such as cooking, food drying and heating domestic water.  We Harvest the Heat and we use the Heat. This series does NOT explore solar panel technology which produces Electricity.  We Harvest the Heat and we use the Heat.

The next few articles will explore Solar Food Dehydration.

Why dehydrate foods?   Why use solar heat?

1. Food Drying provides a way to preserve foods for long periods after the harvest.
2. Solar Heat is Free.

Solar Food Dehydration is one of the simplest examples of how we can harvest and use the Heat from our Sun.

Food Dehydration is one of mankind’s oldest technologies, at least 12,000-year-old. Today, you can go into a supermarket and find many dried food products such as herbs, spices, grains, nuts, fruits, meats and fish.

We mentioned last month, that the ideal conditions for drying foods is the same as for drying laundry: warm, dry air, moving across sun-warmed clothing. 

Similiarly, in a Solar Food Dehydrator, we warm the air with sunlight and move that warmed air across what we want to dehydrate.  We need three functions in our dehydrator: First, a way to warm air.  Second, a means to move the warm air across the food.  Third, a place to put our food to dry.

Typically, in a commercial food dehydrator, the air is warmed with an electric heating element, and a fan moves the warmed air across the food on grills in a box.  And we pay I.C.E. For the electric heat and electric fan.

Typically, in a Solar Food Dehydrator, the air is warmed in a rectangular box with clear plastic or glass on the top side to let warm sunlight enter and hold the warmed air in the box.  The box is open on each end with one end raised off the ground, about one half of it’s length. 

With one end raised we get natural air convection.  Just as in a chimney, like warm air rising from a “fogon”, the warmed air in the inclined box moves up and exits the higher end of the box. 

The top of the heat collector box is connected to the bottom of a cabinet that has internal supports for removable trays.  Food is placed on screen trays which allow warm air to rise through the cabinet, across the food, and exit at the top of the cabinet.

With the Solar Food Dehydrator, we have FREE warm air [no electric heating element] and FREE air circulation [no electric fan].

Here are some advantages and disadvantages for electric and solar dryers:

ELECTRIC

Advantages

• Compact        
• Operate in any weather                                  
• Operate day or night 

Disadvantages

• More expensive to operate
• More expensive to purchase

SOLAR                     

Advantages 

• Less expensive for buy.   
• Less expensive to operate.

Disadvantages

• Larger size, requires space outside
• Daytime use only
• Requires sunny conditions
• Requires more time to dry food

SOLAR DEHYDRATOR DESIGN AND CONSTRUCTION

Here is a type of Solar Dehydrator.

This one is made with plywood and 2x4s.  The collector box cover is plastic. There are a few important details to this design.

• -Can be moved like a wheelbarrow, with wheels in the front and a pair of handles in the rear.  This
• allows easy adjustments during the day as the sun moves through the sky and makes storage easier.
• -There is air circulation control with small doors, near the top. These can be closed at night and other humid times
• -There is screen against insects on the air input and also inside the small doors at the top
• -There are numerous simple trays made with wood frame and screen
• -There is a door that seals well against insects and humid air at night

For more details on this design at:

English   https://www.motherearthnews.com/diy/tools/solar-food-dehydrator-plans-zm0z14jjzmar

Espanol https://www.youtube.com/watch?v=RXWYQqtvs5Y

For more examples and details I recommend that you google,   ‘Secadores Solares’ o ‘Deshidratadores Solares.

There are also designs on my facebook page ‘Soluciones Carbono Neutral’.

The markets.

There are growing markets for healthy foods free of pesticides and chemicals.  Some examples are: dried bananas, dried mangos, dried apples, dried meats, a variety of gluten free flours such as banana, plantain, yucca, sweet potato, etc. and dry soup mixes free of preservative and artificial flavors.

 See you next month when we explore how to use prepare foods and use the Solar Dehydrator.

Training for creation and use of solar dryers

If more than 6 people show interest, I would be glad to host a virtual ZOOM workshop to support your specific questions.  Send a message to Julio at ‘Soluciones Carbono Neutral’ if interested.

Kirk Jackman is founder of ‘Soluciones Carbono Neutral’, and promoter of the use construction and design of solar food dryers and ovens.  He lives in Pérez Zeledón.  He is currently prototyping a commercial scale solar bakery oven.

Follow us on facebook: https://www.facebook.com/Soluciones-Carbono-Neutral-514245642267416/