About the Pedestal Height
Pedestal height calculation determines the minimum height of the mounting structure's support pedestal (post or leg) to achieve the required module tilt angle and bottom-edge clearance above the roof or ground surface — preventing waterlogging damage, maximising airflow under modules, and meeting any fire-access or snow-clearance requirements.
Formula
Back leg height = Front leg height + (module_length × sin(tilt_angle))
- module_length
- Panel length along the tilt direction (m)
- tilt_angle
- Module tilt from horizontal (degrees)
How to calculate it
- 1Define minimum front-edge clearance: 150–300 mm for rooftop (prevents standing water contact); 300–500 mm for ground (grass/vegetation clearance).
- 2Calculate the rise needed: module_length × sin(tilt_angle). For a 2 m panel at 15°: 2 × sin(15°) = 0.518 m.
- 3Front leg height = minimum clearance. Back leg height = front leg height + rise.
- 4Verify structural adequacy: taller pedestals have higher wind bending moments — cross-section and base plate must be rechecked.
Worked example
Rooftop installation: 2 m panel at 15° tilt, 200 mm minimum front clearance. Rise = 2 × 0.259 = 0.518 m. Front leg: 200 mm. Back leg: 200 + 518 = 718 mm. Round up to 750 mm standard section. Check: at 44 m/s wind speed, a 750 mm post with 60×60×4 mm angle section is adequate for a single-panel span.
What you can calculate
- Tilt from heights
- Ventilation clearance
- Height difference
- Rear pedestal
Frequently asked questions
Why does module clearance above the roof matter?
Low clearance (< 100 mm) traps heat under modules — panel temperatures can rise 5–10°C above ambient, increasing resistive losses. It also traps moisture, accelerating frame corrosion. For sloping RCC roofs, clearance must account for drainage paths: the structure must not block rainwater runoff channels.
How does tilt angle affect pedestal height?
Higher tilt increases the height difference between front and back legs, requiring taller (and heavier) back pedestals. For a 2 m panel: at 10° tilt the rise is 347 mm; at 25° it is 845 mm — 2.4× taller. Higher tilt also increases wind uplift force on the structure. The optimum tilt balances maximum annual yield (close to latitude angle) against structural cost (lower tilt = lower structure cost).
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