Solar Panel Angles
Name: Dave Didonato
How does the angle of descending light affect how much
energy a solar panel absorbs?
In at least three ways:
1) The angle that light from the sun makes with the Earth's atmosphere
determines the distance the light must travel through the atmosphere.
The greater this distance the more energy is absorbed by the air before
the light even reaches the solar panel.
2) A large solar panel generally intercepts more light than a small
panel, right? So the cross-sectional area matters. If you were to
turn the panel edge-on to the sun, it would intercept almost no light.
If the area of the panel is A, the cross-sectional area that the panel
presents to the sun is A cos(theta), where the angle theta is defined
to be zero when the panel is pointing directly at the sun.
3) The greater the angle theta, the more light is reflected from the
surface of the panel. This doesn't matter much unless theta is greater
than around 45 degrees or so.
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Update: June 2012