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Wind Load on Module

Wind pressure and force on a module per IS 875-3.

Mechanical

Inputs (SI units)

Regional basic wind speed per applicable wind-load code (e.g. IS 875-3 / ASCE 7).

Signed and negative by convention (suction/uplift acts away from the roof/array surface).

Results

Governing design force per module
4,899 N
Uplift force per module
4,899 N
Downforce per module
3,674.2 N
Design wind speed Vz
44 m/s
Velocity pressure
1,187 N/m² (1.19 kPa)
Reaction per clamp/support
1,224.7 N
4 supports per module
Zone
Interior
✓ PASS — Design wind speed within typical mid-latitude design range.
✓ PASS — Per-support reaction below an indicative 1500 N screening threshold.
⚠ WARNING — Preliminary estimate only — final mounting-structure (MMS) design requires project- and code-specific structural engineering, including fatigue, dynamic gust factors and local anchorage capacity.

Engineering Recommendations

  • →This is a preliminary load estimate for screening only — final structural design of the mounting structure, clamps, purlins and roof/ground anchorage must be verified by a qualified structural engineer against the applicable local wind-load code.
  • →Edge and corner zones typically see 1.5–2× the interior pressure — confirm zone boundaries per the applicable code's zoning diagrams.
  • →Engineering-grade preliminary calculation. Final design must be verified against project-specific site conditions, manufacturer datasheets, applicable standards and utility requirements.

Detailed Calculation Log

Velocity pressure basis: pz = 0.613·Vz² (SI units, per IS 875 Part 3 / ASCE 7-style dynamic pressure formulation).

Save & Load Project

Designs are stored privately in this browser — nothing is uploaded.

Engineering Formula

  • Vz = Vb × k1 × k2 × k3 × kh
  • pz = 0.613 × Vz² (SI, dynamic/velocity pressure — code basis stated)
  • Design pressure = pz × Cp,net (separately for uplift and downforce)
  • F = |Design pressure| × A (× edge amplification if applicable)
  • Reaction per support = F / supports_per_module

IS 875 (Part 3) uses design wind speed corrected by risk (k1), terrain (k2), and topography (k3). Dynamic pressure follows the Bernoulli-based 0.6 constant for air at sea level.

Step-by-step Calculation

  1. 1.Design wind speed VzVb·k1·k2·k3·kh44 m/s
  2. 2.Velocity (dynamic) pressure0.613·Vz²1,186.8 N/m²
  3. 3.Zone amplificationinterior×1
  4. 4.Design uplift pressure|pz·Cp,uplift|×zone1,898.8 N/m²
  5. 5.Design downforce pressurepz·Cp,down×zone1,424.1 N/m²
  6. 6.Total uplift force per modulep_uplift × A4,899 N
  7. 7.Total downforce per modulep_down × A3,674.2 N
  8. 8.Governing (max) force per modulemax(uplift,downforce)4,899 N
  9. 9.Reaction per clamp/supportF_gov / supports1,224.7 N

How to use this calculator: Wind Load on Module

Wind pressure and force on a module per IS 875-3. The example below is calculated by this page's real engine from the displayed inputs.

  1. 1Confirm that the Wind Load on Module matches the quantity or design check you need.
  2. 2Enter Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 using the units printed beside each field.
  3. 3Select the applicable Array zone options; these choices change the calculation method or factors.
  4. 4Calculate, then follow the substituted equations in the worked example and compare the result with any stated limit.
  5. 5Read the assumptions, warnings and cited references before using the result for a financial, medical or engineering decision.

Input guide and example values

Use values from the same measurement basis and time period. Conditional fields appear only when the related option is selected.

InputExample valueWhy it matters
Basic wind speed44 m/sRegional basic wind speed per applicable wind-load code (e.g. IS 875-3 / ASCE 7).
Risk/importance factor k11 -Measured or known risk/importance factor k1 used by the calculation engine.
Terrain/exposure factor k21 -Measured or known terrain/exposure factor k2 used by the calculation engine.
Topography factor k31 -Measured or known topography factor k3 used by the calculation engine.
Height factor kh1 -Measured or known height factor kh used by the calculation engine.
Net pressure coefficient — uplift-1.6 -Signed and negative by convention (suction/uplift acts away from the roof/array surface).
Net pressure coefficient — downforce1.2 -Measured or known net pressure coefficient — downforce used by the calculation engine.
Array zoneInterior zoneSelect the option that matches the real installation or scenario.
Edge-zone amplification factor1.5 -Measured or known edge-zone amplification factor used by the calculation engine.
Module area2.58 m²Measured or known module area used by the calculation engine.
Supports/clamps per module4 -Measured or known supports/clamps per module used by the calculation engine.

Formula inputs & variables for Wind Load on Module

These are the named quantities used by this calculator. When the source formula does not define a mathematical symbol, OneCalcApp keeps the real input label instead of inventing one.

Variable / inputUnitMeaning in this calculation
Basic wind speedm/sRegional basic wind speed per applicable wind-load code (e.g. IS 875-3 / ASCE 7).
Risk/importance factor k1-Measured or known risk/importance factor k1 used by the calculation engine.
Terrain/exposure factor k2-Measured or known terrain/exposure factor k2 used by the calculation engine.
Topography factor k3-Measured or known topography factor k3 used by the calculation engine.
Height factor kh-Measured or known height factor kh used by the calculation engine.
Net pressure coefficient — uplift-Signed and negative by convention (suction/uplift acts away from the roof/array surface).
Net pressure coefficient — downforce-Measured or known net pressure coefficient — downforce used by the calculation engine.
Array zone—Select the option that matches the real installation or scenario.

How the Wind Load on Module works

The Wind Load on Module uses Basic wind speed, Risk/importance factor k1, Terrain/exposure factor k2, Topography factor k3, Height factor kh, Net pressure coefficient — uplift, Net pressure coefficient — downforce, Array zone, Edge-zone amplification factor, Module area, and Supports/clamps per module to calculate Governing design force per module, Uplift force per module, Downforce per module, Design wind speed Vz, Velocity pressure, Reaction per clamp/support, and Zone. Its engine applies Vz = Vb × k1 × k2 × k3 × kh; the worked values below come from that same live calculation rather than a separately typed example.

With Basic wind speed 44 m/s, Risk/importance factor k1 1 -, Terrain/exposure factor k2 1 -, Topography factor k3 1 -, Height factor kh 1 -, Net pressure coefficient — uplift -1.6 -, Net pressure coefficient — downforce 1.2 -, Array zone Interior zone, Edge-zone amplification factor 1.5 -, Module area 2.58 m², and Supports/clamps per module 4 -, the main worked-example result is Governing design force per module = 4,899 N.

How each Wind Load on Module input is used

Basic wind speed

The Wind Load on Module worked example uses Basic wind speed = 44 m/s. This value is passed directly into the calculation, with an allowed minimum 20 and maximum 80. Regional basic wind speed per applicable wind-load code (e.g. IS 875-3 / ASCE 7).

Risk/importance factor k1

The Wind Load on Module worked example uses Risk/importance factor k1 = 1 -. This value is passed directly into the calculation, with an allowed minimum 0.7 and maximum 1.3.

Terrain/exposure factor k2

The Wind Load on Module worked example uses Terrain/exposure factor k2 = 1 -. This value is passed directly into the calculation, with an allowed minimum 0.7 and maximum 1.4.

Topography factor k3

The Wind Load on Module worked example uses Topography factor k3 = 1 -. This value is passed directly into the calculation, with an allowed minimum 1 and maximum 1.36.

Height factor kh

The Wind Load on Module worked example uses Height factor kh = 1 -. This value is passed directly into the calculation, with an allowed minimum 0.8 and maximum 1.5.

Net pressure coefficient — uplift

The Wind Load on Module worked example uses Net pressure coefficient — uplift = -1.6 -. This value is passed directly into the calculation, with an allowed minimum -3 and maximum 0. Signed and negative by convention (suction/uplift acts away from the roof/array surface).

Net pressure coefficient — downforce

The Wind Load on Module worked example uses Net pressure coefficient — downforce = 1.2 -. This value is passed directly into the calculation, with an allowed minimum 0 and maximum 3.

Array zone

The Wind Load on Module worked example selects “Interior zone”. Available choices include Interior zone and Edge / corner zone. This selection may change the method or factor used by the engine, so choose the option that matches the real case.

Edge-zone amplification factor

The Wind Load on Module worked example uses Edge-zone amplification factor = 1.5 -. This value is passed directly into the calculation, with an allowed minimum 1 and maximum 3.

Module area

The Wind Load on Module worked example uses Module area = 2.58 m². This value is passed directly into the calculation, with an allowed minimum 0.1.

Supports/clamps per module

The Wind Load on Module worked example uses Supports/clamps per module = 4 -. This value is passed directly into the calculation, with an allowed minimum 2 and maximum 8.

Wind Load on Module formulas and result interpretation

Formula 1: relationship used

In the Wind Load on Module, Vz = Vb × k1 × k2 × k3 × kh. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 2: relationship used

In the Wind Load on Module, pz = 0.613 × Vz² (SI, dynamic/velocity pressure — code basis stated). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 3: relationship used

In the Wind Load on Module, Design pressure = pz × Cp,net (separately for uplift and downforce). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 4: relationship used

In the Wind Load on Module, F = |Design pressure| × A (× edge amplification if applicable). The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Formula 5: relationship used

In the Wind Load on Module, Reaction per support = F / supports_per_module. The quantities in this relationship come from the named inputs or from an earlier calculation step shown in the worked example.

Governing design force per module

For the displayed Wind Load on Module worked example, Governing design force per module is 4,899 N. Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Uplift force per module

For the displayed Wind Load on Module worked example, Uplift force per module is 4,899 N. Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Downforce per module

For the displayed Wind Load on Module worked example, Downforce per module is 3,674.2 N. Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Design wind speed Vz

For the displayed Wind Load on Module worked example, Design wind speed Vz is 44 m/s. Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Velocity pressure

For the displayed Wind Load on Module worked example, Velocity pressure is 1,187 N/m² (1.19 kPa). Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Reaction per clamp/support

For the displayed Wind Load on Module worked example, Reaction per clamp/support is 1,224.7 N. 4 supports per module Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Zone

For the displayed Wind Load on Module worked example, Zone is Interior. Verify Basic wind speed, Risk/importance factor k1, and Terrain/exposure factor k2 and their units before relying on this output.

Wind Load on Module accuracy, checks and limitations

  • Wind Load on Module units check: confirm Basic wind speed (m/s), Risk/importance factor k1 (-), Terrain/exposure factor k2 (-), Topography factor k3 (-), Height factor kh (-), Net pressure coefficient — uplift (-), Net pressure coefficient — downforce (-), Array zone, Edge-zone amplification factor (-), Module area (m²), and Supports/clamps per module (-) before calculating.
  • Wind Load on Module result check: compare Governing design force per module, Uplift force per module, Downforce per module, Design wind speed Vz, Velocity pressure, Reaction per clamp/support, and Zone with the substituted formula steps and the displayed rounding precision.
  • Wind Load on Module: Use this result for preliminary design and cross-checking. Confirm the applicable code edition, manufacturer data, site conditions and qualified-engineer approval before final design or installation.

Understanding the result

Read the main result together with supporting checks, assumptions, limits and intermediate values.

For a manual check, repeat the first equation, confirm the units and change one input at a time.

Common mistakes when using Wind Load on Module

  • Do not mix units for Basic wind speed (m/s), Risk/importance factor k1 (-), Terrain/exposure factor k2 (-). A unit mismatch changes the input magnitude even when the typed number looks reasonable.
  • Do not leave Array zone on the default choice unless that choice matches the real scenario; the selected option can change the calculation path or factor.
  • Do not replace the displayed Vz = Vb × k1 × k2 × k3 × kh relationship with a different convention without also changing the underlying assumptions; compare like-for-like methods when checking the result.
  • Do not treat Governing design force per module = 4,899 N from the worked example as a universal answer. It belongs to the displayed example inputs and must be recalculated for the actual case.

When the Wind Load on Module is useful

Wind Load on Module is designed for cases where Basic wind speed, Risk/importance factor k1, Terrain/exposure factor k2, Topography factor k3 are known and you need Governing design force per module, Uplift force per module, Downforce per module. The page keeps the live calculator, calculation method and worked example together so the result can be checked instead of treated as a black-box number.

Use the calculator for the scope described by its inputs and notes. The displayed method is Vz = Vb × k1 × k2 × k3 × kh. If the real project or decision needs factors that are not represented here, treat the result as an estimate and add the missing checks separately.

Basic wind speed and Risk/importance factor k1: what changes the answer

The worked example uses Basic wind speed = 44 m/s, Risk/importance factor k1 = 1 -, Terrain/exposure factor k2 = 1 -, Topography factor k3 = 1 -. With those values, Governing design force per module is 4,899 N. Changing an input should be interpreted according to that field's unit, range, option and hint rather than by the number alone.

For this calculator, the main input roles are: Basic wind speed (m/s): Regional basic wind speed per applicable wind-load code (e.g. IS 875-3 / ASCE 7). Risk/importance factor k1 (-): Measured or known risk/importance factor k1 used by the calculation engine. Terrain/exposure factor k2 (-): Measured or known terrain/exposure factor k2 used by the calculation engine. Topography factor k3 (-): Measured or known topography factor k3 used by the calculation engine.

How to sanity-check a Wind Load on Module result

Start by confirming the entered values and units, then compare the substituted working with the displayed formula or calculation steps. Pay particular attention to Governing design force per module, because it is the first worked-example output shown by the live engine.

Finally, compare the result with the assumptions, warnings and related calculators on this page. A nearby calculator can be useful as a cross-check when it measures the same workflow from a different input or output direction.

Next logical calculator

Continue with Solar MMS Structural Design & STAAD Pro Calculator

Solar MMS Structural Design & STAAD Pro Calculator covers the same practical workflow from a related calculation angle, making it a useful cross-check after Wind Load on Module.

Open Solar MMS Structural Design & STAAD Pro Calculator

Design Assumptions

  • • Air density 1.225 kg/m³.
  • • Cp for tilted PV panels ≈ 1.2–1.8 (up-lift dominant).

Engineering Tips

  • ◆Anchor cable ties every 300 mm along frames.
  • ◆Use dynamic gust factor for spans > 6 m.

Warnings

  • ▲Coastal zones need Cp up to 2.2 — check IS 875-3 Table 4.

Standards & References

IS 875 (Part 3):2015ASCE 7-22IEC 61215 §10.16

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