Page 144 - Solar Power in Building Design The Engineer's Complete Design Resource

114 INTRODUCTION TO SOLAR POWER SYSTEM DESIGN

trees, buildings, and tall objects such as power poles or hilled terrain, a comprehen-
sive Solar Pathfinder field survey and analysis must be undertaken. In particular
some agencies such as the Los Angeles Department of Water and Power base their
incentive rebates on the Solar Pathfinder power performance analysis as described
earlier in this chapter.
The following hypothetical shading study is applied to the solar power cogeneration
system reflected in the preceding rebate application. Let us assume that the Solar
Pathfinder diagram in Figure 4.14 represents the site shading diagram. Figure 4.14
depicts Pathfinder dome showing solar platform site shading and Figure 4.15 depicts
Pathfinder showing marked up platform site shading area.
To determine the solar shading performance multiplier, we must first compile the
monthly percentage totals and then calculate the yearly mean or average multiplier. In
this particular example the solar power cogeneration platform is heavily shaded by
trees and surrounding buildings, so we should expect a less-than-optimum energy out-
put performance.
Upon completion of solar shading tabulation and establishment of the shading mul-
tiplier, the overall solar power output performance will be calculated by applying all
power loss factors to the calculated total PTC.

Figure 4.14 Pathfinder dome showing solar platform
site shading.