pv system design and installation lo 9 – mechanical design
TRANSCRIPT
PV System Design and Installation
LO 9 – Mechanical Design
Mechanical Design (3% of text questions)
Task/Skill
9.1. Describe the relationship between row spacing of tilted modules and sun angle,
9.2. Describe the mechanical loads on a PV array (e.g., wind, snow, seismic).
Sun –
Radiant Energy
PV module
Shading issues
Flat roof PV installations
Tilted Modules and Sun Angle
Row Spacing Design/Layout
Reference 2
Tilt Angle Analysis
Definitions
T = Module Tilt Angle (degrees)
H = Module Tilt Height
M = Module Width
D = Module Row Distance
A = Solar altitude (degrees)
S = Frame distance
Tangent (A ) = H / S
S = H / Tangent (A)
What Sun Angle (solar altitude) do you use for design? Think Winter Solstice (9 am to 3 pm).
Right Triangle Geometry
C
A
B
A^2 X B^2 = C^2
C = Square Root (A^2 X B^2)
Tangent (Angle 1) = A/B
Cosine (Angle 1) = B/C
Sine (Angle 1) = A/C
Angle 1 + Angle 2 = 90 degrees
Most calculators use radians to calculate geometric functions. To convert an “angle” to a “radian”;
Radians = (3.14 x Angle) 180
Angle 1 90 degrees
Angle 2
Class Exercise
Calculate required distance between rows of modules on a flat roof