Calculate maximum allowable rail span based on beam deflection limits (L/240) for PV mounting rails.
Input Parameters
Results
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Max Rail Span
ft
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Max Deflection
in
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Bending Stress
psi
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Status
Note: L/240 is the standard deflection limit for PV rail spans. Common aluminum rail spans are 4-6 ft depending on load. Always check both deflection and stress.
Reference
δ_max = 5wL⁴/(384EI) ≤ L/240
L_max = ∛(384EI/(5w×ratio))
Bending Stress σ = Mc/I
M = wL²/8 (uniform distributed load)
Aluminum E ≈ 10×10⁶ psi, Steel E ≈ 29×10⁶ psi