Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?

Solar dryer (dehydration)

Passive

One of 3 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.

What your site needs

Sun-exposed siting with several consecutive dry days achievable in-season

A box where the sun warms air that then flows over trays of fruit, vegetables or herbs. The warm, moving air draws out their water, so mould and bacteria cannot grow. Food keeps for months with no fridge and no running cost, but it needs several dry, sunny days for a batch.

Cost

Low

Upkeep

Seasonal

Skill to build

Basic

Lifespan

10-20 years for the collector/frame structure; glazing cover follows standard glazing lifespan if glazed

Embodied carbon

Low

Space / material use

Medium

Output timing

Weather/time-dependent

Skill to repair

Basic

Inputs

• Solar radiation
• Fresh or perishable food

Outputs

• Preserved food

Compare the 3 ways to meet this need

Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.

• Solar dryer (dehydration) (This page)
  Can I use it? Works in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Regular · Change to daily life: Occasional · Works without the grid: Yes
  Choose it if you want fruit, vegetables or herbs to keep for months with no running cost.
• Pressure canning / autoclave sterilization
  Can I use it? Works in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Medium · Skill to build: None · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes
  Choose it if you want cooked dishes and vegetables to keep for months at room temperature.
• Boiling-water bath preserving (pasteurisation)
  Can I use it? Works in a flat · No rebuilding needed
  What does it cost me? Upfront cost: Low · Skill to build: None · Upkeep: Light · Change to daily life: Occasional · Works without the grid: Yes
  Choose it if you want fruit, jams and pickles to keep for months with just a large pot.

Sources

• General solar-dryer practitioner/NGO durability consensus

Limitations of this page

We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.