Solar Panel Tilt Angle (Fixed Placement)

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Equation / Last modified by mike on 2015/07/30 06:46
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MichaelBartmess.Solar Panel Tilt Angle (Fixed Placement)
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This vCalc solar technology equation computes a "tilt angle" of the pointing face of a solar panel that optimizes solar collection.  The tilt angle is the angle from the vector perpendicular to the surface of the solar panel.  The tilt angle is defined so that 0 degrees has the panel facing straight up.  Positive tilt angles in the Northern Hemisphere, computed by this equation, are from the perfectly vertical pointing vector toward the South. When you're in the Southern hemisphere, the positive tilt angle is from the vertical toward the North.tilt angle.png

Usage

This equation determines a near-optimal tilt angle for fixed placement solar panels at latitudes up to 50 degrees.  The azimuth orientation should be due south and this equation then computes what  the angle from the vertical should be. 1 

The optimum way to mount multiple solar panels would be to mount them on a frame that would hold the surface of all the panels in the same plane as if all the separate panels were part of one larger flat surface. This way of mounting the panels would minimize the total footprint of the panels, the total area of the roof affected by the mounted panels

Typically, solar panels are not mounted this way but are mounted individually to the roof and tilted to achieve the pointing angle above the horizon (which this equation computes).  If individual panels are mounted at an angle to the roof, his has the affect to possibly cast the shadow of one panel on part of the panel immediately behind it when the sun goes low in its path.  This should only occurs a lowest angles of the sun when the incidence angle on the panels is at it's lowest anyway, so this effect may be minimal depending on the angle of the roof to which the panels are mounted.

This affect of panel shadowing another panel can be eliminated by simply separating the panels so that a horizontal plane from the topmost edge of each panel touches the bottom of the next higher panel. Panel shadowing is mentioned in places on the web as if the separation of panels on the roof mounting is a big deal.  In most cases the number of panels being mounted on a roof are not going to exceed roof space.

Relevant Information

The United Stated National Renewable Resource Energy Laboratory's (NREL) Renewable Resource Data Center2  has numerous articles on the application of solar technology, such as:

See Also

Solar Panel Tilt Angle (2 Season adjustment)

References