Page 129 - Solar Power in Building Design The Engineer's Complete Design Resource

SHADING ANALYSIS AND SOLAR ENERGY PERFORMANCE MULTIPLIER 99

of a topographical site diagram of the solar platform, geographic latitude and longitude,
or simply the area zip code. After you have entered the required parameters, the software
automatically calculates the mean yearly shading efficiency multiplier.

Shading Analysis and Solar Energy

Performance Multiplier

One of the significant steps prior to designing a solar power is to investigate the loca-
tion of the solar installation platform where the solar PV arrays will be located. In order
to harvest the maximum amount of solar energy, theoretically all panels in addition to
being mounted at the optimum tilt angle must be totally exposed to sun rays without
any shading that may be cast by surrounding building, object, trees, or vegetation.
To achieve the preceding objective, the solar power mounting terrain or the platform
must be analyzed for year-round shading. Note that the casting of shadows due to the
seasonal rise and fall of the solar angle must be taken into account as it has a signifi-
cant impact on the shadow direction and surface area. For instance, a shadow cast by
a building or tree will vary from month to month changing in length, width, and shape.
In order to analyze yearly shading of a solar platform, solar power designers and
integrators make use of a commercial shading analysis instrument called the Solar
Pathfinder shown in Figure 4.6. The Solar Pathfinder is used for shade analysis in areas

Figure 4.6 Solar Pathfinder and shading graphs.
Courtesy of Solar Pathfinder.