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Solar Water Heater

Flat-plate / ETC collector area for hot-water demand.

Design

Inputs (SI units)

Results

Collector area
3.25 m²
Daily energy
9.3 kWh
Recommended panels (2 m²)
2 × 2 m²

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Engineering Formula

  • E = m × Cp × ΔT (Cp=4.186 kJ/kg·K)
  • A = E / (G × η × 3600) [m²]

Sensible heat law m·Cp·ΔT. Collector area equals daily energy divided by useful insolation, converted to kWh.

Step-by-step Calculation

  1. 1.Energym·Cp·ΔT9.3 kWh
  2. 2.AreaE/(G×η)3.25 m²

Design Assumptions

  • • Water density ≈ 1 kg/L.
  • • Well-insulated tank (< 5% standby loss).

Engineering Tips

  • ◆ETC beats FPC in cold climates (> 4 °C dawn).
  • ◆Size tank 1.5–2× daily draw.

Warnings

  • ▲Add scale-arrestor in hard-water regions.

Standards & References

IS 12933 (FPC)IS 16368 (ETC)

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