What is a sun dryer?

A homemade sun dryer is a simple box that uses sunlight to dry food (fruits, vegetables, fish, maize) faster and cleaner than leaving it on the ground. It protects food from dust, insects and animals and reduces spoilage.

Why make one?

• Low cost — uses local materials (wood, wire mesh, old window glass or polythene).
• Uses free solar energy — good in Kenya's dry seasons.
• Improves food safety and shelf life — less mould and rot.
• Great school or community project.

Simple diagram (how it works)

Materials (local & cheap)

• Wood for frame (reclaimed timber or poles)
• Wire mesh or mosquito netting for trays
• Clear plastic sheet (UV-resistant) or old window glass
• Black sheet / painted metal or black-painted board (absorber)
• Screws/nails, small hinges, and glue
• Thermometer (optional, for school experiments)

Step-by-step build (simple cabinet dryer)

1. Choose size: small box (about 60cm x 40cm x 40cm) is good for practice.
2. Make frame: build a wooden box with a sloping top towards the sun-facing side (south in Kenya if in the northern hemisphere? — in Kenya, face the glass toward the equator: generally north in Southern areas, south in Northern areas; best to place where sun hits most).
3. Black absorber: fit a black-painted board or metal sheet at the bottom to absorb heat.
4. Trays: make 2–4 wooden frames covered with wire mesh or mosquito netting for airflow.
5. Cover: fit clear plastic or glass over the top to let sunlight in and prevent dust and insects.
6. Vents: make small vents at the bottom front (air inlet) and top back (outlet) so warm air can flow across the trays.
7. Place and angle: put the dryer where it receives direct sun most of the day (mid-morning to late afternoon). Tilt top to catch sunlight and allow water to run off.
8. Test: measure inside temperature (if possible) or check that it gets noticeably warmer than outside on a sunny day.

How to dry different foods (Kenyan examples)

• Mango slices — cut thin, pre-treat with lemon water if available, dry 1–3 days until leathery and no juice remains.
• Tomatoes — slice or halve, 2–5 days until leathery/dry.
• Fish (small) — clean well, salt, sun-dry 1–3 days depending on size and weather.
• Maize/beans — dry kernels fully before storage; aim for moisture below 13% (takes several sunny days if already partly dry).
• Groundnuts — dry and then shell; avoid wet season to reduce aflatoxin risk.

Simple tests for dryness (no lab needed)

• Fruits: bend a piece — it should be flexible but not wet or sticky.
• Grains: bite a kernel — it should be hard, not soft; or grind a few and check for mould smell.
• Fish: no soft, wet spots and should break but not be powdery.

Hygiene, safety and good practice

• Wash hands and clean food well before drying.
• Protect dryer from dust and animals — keep top closed when not checking trays.
• Avoid drying during rainy or very humid days — moisture encourages mould and aflatoxins.
• Regularly clean trays and replace worn mesh to avoid insects.
• Store dried food in clean, dry containers (airtight if possible).

Advantages & Limitations

When to dry in Kenya?

Best during dry seasons when humidity is low. In many parts of Kenya, dry months include January–March and June–September, but check your local area — arid and semi-arid counties (e.g., Turkana, Kitui) get long sunny periods while highland areas can be misty.

School project idea

Build two small dryers: one with a clear plastic cover and one open tray. Measure inside temperature and drying time each day. Record results and show which keeps food cleaner and dries faster.

Quick checklist before you start

• Clean and cut produce uniformly.
• Use clean trays and protective cover.
• Place dryer in direct sun and secure it from animals.
• Check daily for pests, damp spots and even drying.