Solar Photovoltaic Basics, A Study Guide for the NABCEP Entry Level Exam by Sean White4324

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Solar energy fundamentals
Figure 4.1 The atmosphere filters more light at greater angles
Sun
At an
angle
Sun
Overhead
Top of
Atmosphere
1.5 Atmosphere
1 Atmosphere
AIR
Sunlight (irradiance) at a
greater angle is filtered by
increased atmosphere.
EARTH
1.5 Atmospheric Mass (AM) is the spectrum of light, which is tested in the
factory. The test conditions are simulated with a flash of light and a filter to
simulate 1.5 AM during PV module testing. The thicker the atmosphere, the less
light will make it to the PV. This means that at higher elevations, sunlight will
have less atmosphere to travel through, which will increase performance. Also,
around noon and summer solstice, the sun is highest in the sky and will have
less atmosphere to travel through, than when the sun is lower in the sky.
The atmosphere is relatively thin compared to the earth. If we painted
over a globe, the thickness of the paint would be about that of the
atmosphere. If we could drive our car straight up for five minutes at
highway speeds, we would reach the edge of the atmosphere. That is
not a lot of room to dump 100s of years of CO 2
pollution.
LATITUDE
The equator is zero latitude and the North Pole is 90 degrees latitude. Just
like degrees in a compass, the equator is at a 90 degree angle from the North
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