Energy in the 21st Century

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Photovoltaics
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Photovoltaics
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Photovoltaics
PV Applications
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Photovoltaics
Multicrystalline silicon casting, wafers, and PV
cells (
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Photovoltaics
PV cells
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Photovoltaics
Cross-sectional view of a PV cell, showing the
photo-receptive surface and the p/n junction
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Photovoltaics
An n-type material has an increased number of
electrons the p-type material has vacancies as a
result of missing electrons (p positive).
The p-n junction is the critical component of
a functioning solar cell.
The Photovoltaic Principle - Cells
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Photovoltaics

• The majority of the light is absorbed in the
  p-silicon layer
• some electrons push through the p-n junction
  into
• the n-silicon layer.
• The freed electrons flow through the wire grid

The Photovoltaic Principle
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Photovoltaics

• One single-crystal silicon solar cell with a
  surface area of approximately 100 cm2 (16 in2)
  generates a current of 3 A at a voltage of 0.5 V
  when exposed to full sunshine.

The Photovoltaic Principle
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Photovoltaics
Efficiencies
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Photovoltaics
PV Modules
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Photovoltaics
Flexible photovoltaic modules made of amorphous
silicon (a-Si) on stain - less steel
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Photovoltaics
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Photovoltaics

• The light-generated current flows out of the cell
  surface and through a metal grid called the front
  contact.
• The cells bottom layer is called the back
  contact and forms a bridge to an external
  circuit.

The Photovoltaic Principle - Modules
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Photovoltaics
I-V curve and characteristic parameters for a
typical module
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Photovoltaics

• Open circuit voltage (VOC) no current.
• Pn under STC peak power (Vn and In).
• Short circuit current (ISC)

The Photovoltaic Principle - Modules
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Photovoltaics
Solar cells 100 mm x 100 mm, 36 in series
An example of a typical PV module data sheet
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Photovoltaics

• Voltage is derated by 0.0022 V/K above STC
• In bright sunlight module is 35F-70F above the
  ambient temperature.

The Photovoltaic Principle - Modules
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Photovoltaics
PV System Arrangement
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Photovoltaics
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Photovoltaics
Advantages of PV
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Photovoltaics
Industry Claim
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Photovoltaics
)Assuming volume installations. Individual
rooftop systems can be up to twice this price
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Photovoltaics
More Cautious AEE Assessment
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Photovoltaics
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Photovoltaics
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Photovoltaics
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Photovoltaics
Holographic PV Planer Concentrator - HPPC
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Photovoltaics
Holographic PV Planer Concentrator - HPPC
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Solar Thermal
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Solar Thermal
Conventional Flat Plate Collector
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Solar Thermal
Passive Thermo-siphon Collector
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Solar Thermal
Evacuated Tube Collector
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Solar Thermal
Solar Hot Water System
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Solar Thermal
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Solar Thermal
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Solar Thermal
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Solar Thermal