In the case of a solar module or solar collector, the azimuth angle is the horizontal angle between exact south and the direction the surface of the device is facing. The other important angle involved in setting up a solar module or collector is the tilt angle – the angle at which the device is tilted away from the horizontal.
Because the Sun's position in the sky changes throughout the day, a static module or collector is hardly ever optimally placed to receive the Sun's rays at right angles to its surface. The best compromise solution, in the case of a module/collector that will never be moved, is to set up the device facing south (or north in the southern hemisphere) at a tilt angle equal to the latitude. An improvement in power- or heat-generating capacity of anywhere from 10% to 40% is achievable if the module/collector is moved to keep the incoming sunlight more perpendicular for more of the time. In some cases, this may involve manually adjusting the angle of the device several times a year to compensate for the Sun's seasonal north to south migration. In order to follow the Sun's daily east-to-west motion, tracking arrays are available.