Passive solar throughput (~10 L/m²/day) means collector area scales directly with population served
#00060
Solar evaporation yields ~10 L/m²/day outdoors—near the physical ceiling, not an engineering gap. Full domestic use (~50–100 L/person/day) requires 5–10 m² per person; a 10,000-person town needs 5–10 hectares. This bounds the technology to household/hamlet scale, not municipal su
Parent issue
#00056 Passive solar-thermal interfacial crystallizer using laser-textured superwicking black metal
Sustainable Development Goals
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Description
The problem
Solar-thermal evaporation is fundamentally limited by the solar energy arriving per unit area. The measured outdoor figure of ~10.3 L/m²/day is close to the physical ceiling, not an engineering shortfall to be optimised away. That number sets hard sizing limits:
- Drinking water alone (~2–3 L/person/day): ~1 m² serves 3–4 people.
- Full basic domestic use (~50–100 L/person/day): ~5–10 m² of collector per person.
- A 10,000-person town therefore needs on the order of 5–10 hectares of panels.
By contrast, a single containerized RO unit produces ~75,000 L/day from a shipping-container footprint.
Implications for deployment
This is a positioning fact, not a defect. It rules the technology out of dense municipal supply and in for decentralized, household- and hamlet-scale, off-grid coastal use—specifically drinking and cooking water rather than full domestic demand. Solutions claiming to "solve water for billions" are mis-scoped; the honest claim is a distributed, low-maintenance drinking-water tier where RO is uneconomic.
What a resolution needs
Realistic per-household and per-village area, siting and cost envelopes, and a clear statement of which demand tier (drinking only vs. full domestic) a given deployment targets.
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