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Solar Energy Physics 1303
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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 Solar water heater system has four components: Collector Tank Pump Controller
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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 Let’s work a problem
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Solar Hot Water Heater
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Flat Plate Collector Problem A flat plate solar collector is used as a solar hot water heater. The collector area equals 20 square meters. The collector is located in a location with annual average daily solar insolation equal to 5.0 kWh/square meter/day.
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1. Calculate the amount of solar energy incident on this collector each day. Solar Energy = = 5.0 kWh / sq m / day 20 sq m = 100 kWh / day
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2.Assuming that the efficiency of the solar collector and the rest of the system equals 50%, calculate the average daily energy produced (as hot water) by this system. Express your answer in kWh/day. Average Produced Energy/day = = 100 kWh / day 0.50 = 50 kWh / day
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3. Calculate the amount of energy produced by this system each year. Express your answer in kWh. Annual Energy Production = = 50 kWh/day 365 day/year = 18,000 kWh / year
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4. Assuming that the solar energy replaces the heating of hot water by electric energy and that electric energy cost 10¢/kWh, calculate the yearly savings in electricity costs as a result of using the solar hot water system. Express your answer in $/year. Money Saved = = 18,000 kWh $0.10/kWh = $1,800 / year
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5. Suppose this solar hot water system were to cost $5,400 (installed). Calculate the payback period for this system Payback = Cost / Savings = $5,400 / $1,800 /year = 3 years
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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 that I use in a small 3 rd floor lab in MMS
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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 Let’s work a PV problem.
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Photovoltaic Power System
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PV Problem A photovoltaic power system has a collector area equals 100 square meters. The collector is located in a location with annual average daily solar irradiance (insolation) equal to 5.0 kWh/square meter/day.
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1. Calculate the amount of solar energy incident on this collector each day. Solar Energy = = 5.0 kWh / sq m / day 100 sq m = 500 kWh / day
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2.Assuming that the efficiency of the PV array and the rest of the system equals 10%, calculate the average daily energy produced (as electricity) by this system. Express your answer in kWh/day. Average Produced Energy/day = = 500 kWh / day 0.10 = 50 kWh / day
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3. Calculate the amount of energy produced by this PV system each year. Express your answer in kWh. Annual Energy Production = = 50 kWh/day 365 day/year = 18,000 kWh / year
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4. Assuming that the cost of electric energy equals 10¢/kWh, calculate the value of the electricity produced by this system annually. Value of energy or Savings = = 18,000 kWh $0.10/kWh = $1,800 / year
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5. Suppose this PV system were to cost $27,000 (installed). Calculate the payback period for this system. Payback = Cost / Savings = $27,000 / $1,800 /year = 15 years
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Solar Energy Do you think solar energy will able to replace a significant fraction of the energy needs of our society?
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