viridian solar wind load calculator

Wind Loading Calculator

USE ONLY FOR VIRIDIAN SOLAR PRODUCTS

PROJECT

Project numberProject NameClient

INPUTS

SiteBasic wind speed (from map) 23 m/s

Site altitude above sea level 10 m

Distance from the sea 10 km

Location type town

Installation

Roof height 5 m

Parapet > 200mm high YesRoof Zone EdgePanel tilt angle 10 degrees

The roof edge zone width is 0.1 x the longest roof dimension

RESULTS

Fixed System Free-standing System

Peak force on each bracket per panel

Number of 450 x 600 x 50mm concrete slabs per panel

V20E or PV20 V20E or PV20 5.8Fh max 145 N V30E or PV30 8.8Fv max 481 NFv min -296 N Dead load on roof per panel (including panel and ballast tray)

V30E or PV30 Load Uniformly Distributed

Fh max 217 N V20E or PV20 259 kg 113

Fv max 709 N V30E or PV30 376 kg 164Fv min -457 N

Example

Version 1.2

Edit the values above to reflect those of the project under consideration.

The calculation is based on BS6399-2:1997. Viridian Solar has added no additional loading factors to the result. The coefficient of friction is assumed to be 0.4 (rubber/steel), topography is assumed to be insignificant. If in doubt, consult a structural engineer.

(dynamic plus static loads, double the value for bracket between two panels)

kg/m2

kg/m2

For a free standing system of 10 solar panels in a single row, it is calculated that the required number of concrete slabs is 7.7 per panel. The total number of slabs is therefore 7.7 x 10 = 77. 10 panels require (n+1) = 11 ballast trays, so the number of slabs per ballast tray is calculated to be 77/11 = 7

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Wind Loading Pressure for Solar Panel on Open Framework

BS 6399-2:1997 Loading for Buildings Part 2 : Code of Practice for wind loads

From Inputs PageSite Altitude 10 m above sea levelLocation townDistance from sea 10 km

Building Height 5 m

Include Internal Pressure 0

Vb 23 m/s

Site Wind SpeedVs = Vb x Sa x Sd x Ss x Sp

Sd - site direction factor - set to 1 when the orientation of the building is unknownSs - seasonal factor - set to 1 when the building is permanentSp - probability factor - set to 1 for 50 year stormSa - Site altitude factor = 1 + 0.001 x altitude in m

Vs = 1.01 Vb

Effective Wind SpeedVe = Sb x Vs

Sb is based on height of building and whether it is in the country or town

In country or up to 2km into townBuilding Distance to sea (km)Height < 0.1 2 10 >100 1

5 1.65 1.62 1.57 1.45 2

10 1.78 1.78 1.73 1.62 3

15 1.85 1.85 1.82 1.71 4

In townBuilding Distance to sea (km)Height < 0.1 2 10 >100 1

5 1.5 1.45 1.36 2

10 1.73 1.69 1.58 3

15 1.85 1.82 1.71 4

Sb 1.45

Ve = 1.4645 Vb= 33.6835 m/s

Dynamic Pressure

695 Pa

qs = 0.613 Ve2

qs =

External Pressure

Ca = 1 for an element as small as a solar panel

Cp,net from lookup table

From BRE Digest 489, Wind loads on roof based PV systems

Table 4 Pressure coefficients Cp,net for PV modules based on open support structures

Roof zoneNo Parapet Parapet >200mm

Cp min Cp max Cp min Cp maxCorner -1.8 1.2 -1.5 1Edge -1.6 1.2 -1.2 1Central -0.6 0.6 -0.6 0.6

Table 5 Pressure coefficients Cp,net for PV modules based on enclosed support structures

Roof zoneNo Parapet Parapet >200mm

Cp min Cp max Cp min Cp maxCorner -1.7 0.5 -1.7 0.5Edge -1.6 0.5 -1.2 0.5Central -1.0 0.5 -1.0 0.5

NotesEdge zone is L/10 wide, where L is largest plan dimension of roof.

Conservatively consider location to be an edge

Parapet 2Central/Edge/Corner 1

Cp min from table 4 -1.2Cp max from table 4 1

Pe min -835 PaPe max 695 Pa

Pe = qs Cp,net Ca

Imposed Loads on Roof Due to Wind Load

V20/PV20

Positive Pressure 695 Pa Negative Pressure -835 Pa

FH FH

242 - 290 F FV F FV

1,391 1,370 - 1,669 - 1,644

W W510.12 510.12

459 N 481 N -271 N -296 N

NOTES:Loads shown are for each side of each solar panel.There is a horizontal force to react as well as the vertical force.

Area 2 Area

Angle θ 10 degrees _Theta

Panel and frame weight 510 N _W

m2

θ θ