Solar Energy

1
Solar Energy

• Physics 1303
• 3/26/03

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Three forms of solar energy.

• Passive Solar
• Active Solar
• Photovoltaic

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Passive Solar Energy

• Sensible architectural design
• Use sun in the winter
• Avoid in the summer.
• Cold climates- large glazing which may be
  insulated at night and opened during the day.
• Hot climates - blocking the sun and providing
  good ventilation.  

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Passive Design

• Arizona Cliff Dwelling is an example of
  traditional low-tech solution to space heating
  and cooling needs.

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Passive Design

• This is a modern New Mexico version.
• There is movable isolation to put in place at
  night.

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Passive Design

• Another interesting design.
• The wall is down and the passive collector is
  collecting solar energy

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Passive Design

• In this mode, the wall is up and the building is
  storing solar energy or blocking summer heat gain.

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An innovative passive design

• Roof Pond House in Atascadero, California

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Active Solar Energy

• Use pumps and solar collectors to provide energy.
  
• Two types of solar collectors
• flat plate
• concentrating

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Flat Plate Collector

• Made of a black absorbing plate with water
  running through it or air blowing past it.
• Usually a flat plate collector has a glazing to
  stop heat from escaping.
• Efficiency 50 or better.

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Flat Plate Collector Hot Water Heater

• Low cost heater in the roof of this modest Miami
  house

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Flat Plate Collector Hot Water Heater

• Low cost heater in the roof of this modest San
  Antonio house

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Flat Plate Collector Hot Water Heater

• Low cost heater in the roof of this modest Miami
  house

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Flat Plate Collector Hot Water Heater

• Solar water heater system has four components
• Collector
• Tank
• Pump
• Controller

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Flat Plate Collector

• Flat plate collectors being tested.

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Flat Plate Collector

• Flat Plate Collector components
• Plate with tubing
• Insulation
• Glazing

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Concentrating Collector

• A concentrating collector includes some kind of
  lens or mirror.
• Tracks the sun.
• High temperature.
•  Efficiency near 50.

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Concentrating Collector

• Components
• Optics
• Glazing
• Absorber
• Insulation
• Tracking

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Concentrating Collector

• This one uses a mirror and has no glazing

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Concentrating Collector

• Used to be on the roof of the Bell center.

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Concentrating Collector

• This is the solar concentrating collector on the
  CPS Headquarters building on San Pedro.
• It runs the air-conditioning system

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Flat Plat Collector Problem

• Stop and work the problem.

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Photovoltaics

• Photovoltaic systems convert solar energy
  directly into electricity. They have efficiencies
  near 10.

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Photovoltaics

• PV-powered airplane.
• Is this really a good idea?

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Photovoltaics

• PV arrays are widely used for low power loads.

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Photovoltacis

• A PV array is made up of several panels and a
  panel is made up of several cells.

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Photovoltaics

• A complete system has an array, a battery, an
  inverter and a load.
• The system can supply either DC or AC loads.

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Photovoltaics

• The inverter converts the DC voltage from the PV
  array into an AC signal to power AC loads or to
  connect to the grid.

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Photovoltaics

• Laurel Kaesler and Frank Ehman designed and built
  the PV Project in the Physics Department

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Photovoltaics

• The PV project has 4 components
• Array
• Controller
• Battery
• Load

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Photovoltaic

• Controller

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Photovoltaics

• The load is a pair of fluorescent lights in my
  Physics office.
• These lamps supply the only light that I use in
  this office.

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Photovoltaic

• This is the solar array on the CPS Headquarters
  building on San Pedro.

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Photovoltaic

• The output of the array is inverted into an AC
  voltage and fed back to the grid.

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Photovoltaics

• A high-tech solution is to use PV to capture
  sunlight as electricity and use the electricity
  to produce microwaves that are beamed back to
  earth.

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PV Problem

• Stop and work the problem.

37
Solar Energy

• Do you think solar energy will able to replace a
  significant fraction of the energy needs of our
  society?