PV System Components

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PV System Components

• Advanced Engineering
• The Technology Academy _at_ Landstown High School

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What is a solar cell?

• Solid state device that converts solar energy
  directly into electrical energy
• Efficiencies from 10- 80
• No moving parts
• No noise
• Lifetimes of 20-30 years or more

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Cross Section of Solar Cell
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How Does It Work?

• The junction of dissimilar materials (n () and p
  (-) type silicon) creates a voltage,
• Energy from sunlight knocks out electrons,
  creating a electron,
• Connecting both sides to an external circuit
  causes current to flow,
• In essence, sunlight on a solar cell creates a
  small battery with voltages typically 0.5 volt DC,

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Combining Solar Cells

• Solar cells can be electrically connected in
  series (voltages add) or in parallel (currents
  add) to give any desired voltage and current,
• Power (Watts) output is calculated P I x V
• Photovoltaic cells are typically sold in modules
  (or panels) of 12 volts with power outputs of 50
  to 100 watts.
• These are then combined into arrays to give the
  total desired power or watts.

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Cells, Modules, Arrays
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Other System Components

• While a major component and cost of a PV system
  is the array, several other components are
  typically needed. These include
• The inverter DC to AC electricity
• DC and AC safety switches
• Batteries (optional depending on design)
• Monitor (optional but a good idea)
• Ordinary electrical meters work as net meters

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The Photovoltaic Array with its other electrical
components
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PV was developed for the space program in the
1960s
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PV Price and Quantity Manufactured Relationship
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The PV Market

• Solar Calculators
• REMOTE POWER
• Lighting
• Buoys
• Communications
• Signs
• Water Pumping
• Mountain Cabins

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Photovoltaic Array for Lighting
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Telecommunications Tower
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Remote Water Pumping in Utah
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Recreation Vehicle Outfitted with Solar Panels
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Solar Lanterns for Landscaping
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A Solar Driven Band
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The PV Market

• As prices dropped, PV began to be used for
  stand-alone home power.
• If you didnt have an existing electrical line
  close to your property, it was cheaper to have a
  PV system (including batteries and a backup
  generator) than to connect to the grid.
• As technology advanced, grid-connected PV with
  net metering became possible.

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NET METERING

• In net metering, when the PV system produces
  excess electricity, it is sent to the grid
  system, turning the meter backwards.
• If you are using more power than is being
  produced, or it is at night, the electricity is
  received from the grid system and the meter turns
  forwards.
• Depending on PV size and electrical consumption,
  you may produce more or less than you actually
  use.
• Individual houses may become power producers.

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Net Metering can be done with or without a
battery backup
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BATTERIES

• Batteries can be used to provide long-term or
  short-term electrical supply in case of grid
  failure.
• Many grid-connected houses choose to have a small
  electrical battery system to provide loads with
  power for half a day in case of outage.
• Larger number of batteries are typically used for
  remote grid-independent systems.

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2 KW PV on Roof with battery storage. Solar hot
water collectors and tank
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PV On Homes

• PV can be added to existing roofs.
• While south tilted exposure is best, flat roofs
  do very well.
• Even east or west facing roofs that do not have
  steep slopes can work fairly well if you are
  doing net metering since the summer sun is so
  much higher and more intense than the winter sun.
  
• The exact performance of any PV system in any
  orientation is easily predictable.

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Photovoltaic Array on Roof and as an Overhang
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½ KW PV System Installed along Roof Ridge
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California Home PV Installation
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PV on House
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2.4 KW System under Installation in New Hampshire
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PV Installed at Roofline on Building at Frost
Valley, NY
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PV Panels on Tile Roofs in Arizona
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PV on Roof in California
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Other Mounting Systems?

• If it is impossible or you dont want to put a PV
  system on your existing roof, it is possible to
  pole mount the arrays somewhere near the house as
  long as the solar exposure is good.
• Pole mounted solar arrays also have the potential
  to rotate to follow the sun over the day by
  installing a sun tracking system,
• Sun tracking systems can provides a 30 or more
  boost to the PV system performance.

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Pole Mount for Solarex Modules
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Pole Mounted PV
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Pole Mounted PV
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Roof Integrated PV

• If you are doing new construction or a reroofing
  job, it is possible to make the roof itself a
  solar PV collector.
• This saves the cost of the roof itself, and
  offers a more aesthetic design.
• The new roof can be shingled or look like metal
  roofing. A few examples follow.

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Solar Roofing Shingles
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Roof Integrated Photovoltaics in Misawi, Japan
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Roof Integrated PV in Japan
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Roof Integrated PV in Maine
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Roof Integrated Photovoltaic System in Colorado
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Roof Integrated PV (objects below chimney are
solar hot water collectors)
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PV Installation in Planned Community in Germany
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