raw · articles · ingested 2026-07-02
DIY Phase Change Material for Heat Storage (BuildItSolar)
confidence: low
Source: https://www.builditsolar.com/Experimental/PCM/DIYPhaseChangeMaterial.htm
Source: BuildItSolar (Gary Reysa). Maker authority, not peer-reviewed. Credibility: Low (DIY, unverified build) — confidence low; useful for practical hazards.
Key points
- Recipe: CaCl₂·6H₂O + NaCl + KCl + ~2% SrCl₂·6H₂O nucleator; ~26 °C freeze / 30 °C melt (comfort band).
- Containers: rigid plastic, walls ≥0.035 in (1-L PET bottles); or transparent 10-mil polycarbonate (GE Lexan) film cavities. Must be sealed against water gain/loss (hygroscopic).
- Hazards: ~10% volume expansion → need headspace; overheating >40 °C permanently kills nucleation centers → supercooling; verify water content.
- Honest gap: no verified build / no measured result.