Transcript Solar Cells

Solar Energy- Photovoltaics (solar cells)
Photovoltaics
• Photovoltaics generate constant electricity– direct
current
• Electrical terms:
– Voltage (difference) (V): Amount of energy per charge
required to move charge around a circuit
– Current (I): Moving charge
• Buildings are powered by alternating current. An
inverter is needed to use a photovoltaic to power
appliances in the home to convert to alternating
current
Electric Circuits
An electric circuit is often compared to a pipe system
Light Intensity And Photovoltaics
• Light Intensity: a measure of the
energy of the light
• The higher the intensity, the more
photons generated, hence, greater
current and voltage
Light wavelength and photovoltaics
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Good website on waves
Speed of light c= frequency (f)* wavelength (l)
c=f l =3 ×108 m/s
Frequency f: # of cycles per second that pass a given point
Wavelength l : Length of a single cycle of the wave
Good website on EM waves
Photovoltaics: Amount of current/voltage depends on
wavelength
• Silicon: Best at infrared wavelengths (l=1mm)
Spectral response: he ratio of the current generated by the
solar cell to the power incident on the solar cell .