What is Sunlight?
How do Solar
Light (solar radiation)
arrived on the
earth in the form of
Photons are powerful enough to
knock electrons around
The Photoelectric Effect
Observed and Described 1839… by Becquerel, Hertz, and Thomson.
Explained by Einstein 1905
What are Solar Cells Made Of?
Solar Cell Structure:
b. Contact Grid
c. The Antireflective Coating (AR Coating)
d. N-Type Silicon
e. P-Type Silicon
f. Back Contact
Two Essential Layers
A = n-type silicon (has free electrons)
B = p-type silicon (has free electron holes)
Sunlight knocks electrons from B to A.
• The electrons have to travel the circuit to
get back to layer B.
• Solar Cells produce direct current (like regular
• Solar Cells are about 10 -25% efficient
A typical single crystal silicon PV cell of 100 cm2 will
produce about 1.5 watts of power at 0.5 volts DC and 3
amps under full summer sunlight (1000Wm-2).
• Power in Watts = Volts x Amperes
• Connecting cells in series increases voltage (additive)
and keeps amperage constant
• Connecting cells in parallel increases amperage
(additive) and keeps voltage constant
Need to configure
panels to desired
You need a regulator, storage
battery, DC AC converter
How much does it cost?
“To give you an idea of how much a house system would
cost, let's consider the Solar House -- a model residential
home in Raleigh, North Carolina, with a PV system set
up by the North Carolina Solar Center to demonstrate the
technology. It's a fairly small home, and it is estimated
that its 3.6-kW PV system covers about half of the total
electricity needs (this system doesn't use batteries -- it's
connected to the grid). Even so, at $9 per Watt, this
installed system would cost you around $32,000. “
Obama’s Energy Campaign Speech 13:19
Obama 8 min