Neptune 13458-000, Installation And Maintenance Manual

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R900 Gateway Installation and Maintenance Guide 77
Appendix A Solar Power Information
Appendix A provides information on the installation of the solar panels.
Installation Considerations for Solar Panels
Solar panels should be installed in a location where they receive maximum
sunlight throughout the year. When choosing a site, avoid trees, buildings, or
obstructions which could cast shadows on solar panels especially during the winter
season when the arc of the sun is lowest over the horizon. See "Facing True South"
on this page.
Magnetic Declination
Correction for Magnetic Declination and Solar Panel Tilt
Facing True South
For optimum performance, your photovoltaic (PV) array (solar panel) should face
true south in the Northern Hemisphere or true north in the Southern Hemisphere.
However, when determining direction using a magnetic compass, indicated
bearings vary from true bearings because of the difference between the location of
the true magnetic north poles. This angular difference varies with location on the
globe and is called the declination. Values of declination for the contiguous
United States and portions of Mexico, Canada, and the Caribbean are shown on the
map in Figure 98 – page 79. In order to correct for magnetic declination when
sighting your solar panel, complete the following steps.
1. Locate your site on the map shown in Figure 98 – page 79.
2. Interpolate the value for magnetic declination in degrees based on the lines of
constant declination (isogonic lines) shown in Figure 98 – page 79. For
example, the declination of Washington, D.C. is approximately -11°, for
Chicago, IL, -1°, and for Los Angeles, CA, +14°.
3. Determine magnetic south at your site using a magnetic compass.
If the local declination found in step two is negative, true south is that number of
degrees added to magnetic south. For example, at Washington D.C., true south
is the same as 180° + 11° = 191° indicated.
If the local declination found in step two is positive, true south is that number of
degrees subtracted from magnetic south. For example, at Los Angeles, true
south is the same as 180° - 14° = 166° indicated.