Permanently mounted modules should be For proper operation, the modules must be faced as close as possible toward the equator. In the Northern Hemisphere, this direction is true south. In most areas, this varies from magnetic south given by a compass. A simple correction must be made. First find the magnetic variation from the isogonic map shown below. This is given in degrees east or west from magnetic south. For example, a site in western Montana has a magnetic variation of 20º east. This means that true south is 20º east of magnetic south. On a compass oriented so the needle is at 360º, true south is in the direction indicated by 160º. The modules should be installed within 20º of true south. In areas with morning fog, the array can be oriented up to 20º toward the west to compensate. Conversely, arrays in areas with a high incidence of afternoon storms can be faced toward the east. If the array is located in the Southern Hemisphere the array must face true north.
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tilted up from the horizontal. The correct tilt angle varies with the time of
year the system is used and the latitude of the site. The tilt angle is measured
from the horizontal plane, not from a pitched roof or hillside. The tilt should
be within 10 degrees of your latitude. For example, a system used throughout the
year at a latitude of 35º can have a tilt angle of 25º to 45º without a
noticeable decrease in annual performance.
