Solar Powered Housing

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Solar Powered Housing

• Darryl Birtwistle
• Energy, Society, and Climate
• November 6, 2002

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Topics of Discussion

• Basic Concept.
• Whats required for an efficiently solar powered
  house.
• Basic technology of solar power.
• Solar home systems (different parts).
• Determining cost and size.
• How solar power can benefit you.
• Examine an efficient solar house.

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Basic Concept

• Takes energy from the sun and converts it into
  electrically energy.
• This energy is used to run appliances or charge a
  battery.
• The battery can be used to run appliances when
  the solar panels are not producing energy.

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Whats required?

• Reduce amount of energy consumed.
• Efficient house design.
• Efficient energy usage.
• Use of effective solar power technology.

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Effective House Design

• Properly sealed house
• Properly insulation
• Proper window design (passive heating)
• Proper materials
• Efficient air infiltration

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Efficient Energy Usage

• Efficient appliances
• Energystar
• Energy conservative
• Turning off lights.
• Turning down A/C.
• Keeping windows and doors closed.

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Photovoltaic Cells
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Photovoltaic Cells

• Photovoltaic take advantage of the fact that
  light can knock electrons out of atoms of certain
  substances.
• Cells consist of two silicon layers.
• Layer facing the sun is positively charged while
  layer beneath is negatively charged.
• Sun hits the cell and knocks electrons from
  positively charged surface to the negatively
  charged surface, creating an direct electric
  current (DC - flowing one way).
• The electricity is then sent through an inverter
  to convert it to an alternating current (AC
  Flowing both ways).

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Photovoltaic Cell
Photovoltaic cell includes semiconducting
materials (usually silicon), top and bottom
metallic grids to transfer the electrons, a glass
cover or other type of transparent encapsulant to
seal the cell and keep weather out, and an
antireflective coating to keep the cell from
reflecting the light back away from the cell.
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Photovoltaic Cells

• Two main types of silicon cells are crystalline
  and thin-film.
• Crystalline
• Highly efficient (20), the production process is
  expensive. (lifetime of over 20 yrs)
• Thin-film
• Lower efficiency, less expensive. (lifetime of at
  least 10 years)
• More efficient models are being developed (40)

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Photovoltaic Modules

• Photovoltaic cells produce little energy by
  themselves.
• Photovoltaic cells are connected to form modules
  or panels that can produce a large amount of
  energy.
• Combing cells can produce anywhere from a few
  milliwatts (calculator) to several megawatts.

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Photovoltaic Modules

• Modules are measured in units of "peak watts
  (Wp).
• This refers to the power output of the module
  under "peak sun" conditions (1000 Watts per
  square meter).
• "Sun hours," or "insolation," refers to the
  average number of peak sun hours.
• North America averages 3 to 4 peak sun hours per
  day in summer.
• Equatorial regions can reach above 6 peak
  sunlight hours.

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Solar Home System

• Each SHS includes a PV module, a battery, a
  charge controller, an inverter, wiring,
  fluorescent lights, and outlets for other
  appliances.
• The size of the SHS (20Wp, 35Wp, 50Wp) determines
  the amount of energy produced.
• A standard small SHS can operate several lights,
  a black-and-white television, a radio or cassette
  player, and a small fan.
• A 35 Wp SHS
• four 7W lamps each evening
• several hours of television.

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Solar Home System
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Solar Home System (Module)

• Most efficient orientation of a solar module is
  at true south.
• To determine, divide the span of time between
  sunrise and sunset in half.
• The angle of the solar array can be anywhere from
  your lattitude plus 15 degrees to lattitude minus
  15 degrees for a yearly fixed mount position.

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Solar Home System (Module)

• Your lattitude offers the best year-round
  position.
• -15 degrees will give you more insolation during
  winter months.
• 15 degrees will give you more insolation during
  the summer months.

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Solar Home System (Module)
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Solar Home System (Inverter)

• Inverter is used to transform the direct current
  (D/C) to an alternating current (A/C).
• Different inverters can provide different
  voltages and different efficiencies.

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Solar Home System (Charge Controller)

• Controls the flow of electricity between the
  module, battery, and the loads.
• Prevents battery damage by ensuring that the
  battery is operating within its normal charge
  levels.
• If the charge level in the battery falls below a
  certain level, a "low voltage disconnect (LVD)
  will cut the current to the loads, to prevent
  further discharge.
• Likewise, it will also cut the current from the
  module in cases of overcharging.
• Indicator lights on the controller display the
  relative state of charge of the battery.

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Solar Home System (Battery)

• An electrochemical storage battery is used to
  store the electricity converted by the solar
  module.
• During the day, electricity from the module
  charges the storage battery.
• During the evening, the battery is discharged to
  power lights and other appliances.
• Batteries are typically sized to provide several
  days of electricity in the event that overcast
  weather prevents recharging.

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Solar Home System (Lighting)

• Compact fluorescent light bulbs as well as
  fluorescent tube lights are used for lighting.
• An SHS normally includes two to six lights.
• An SHS can provide substantially higher lighting
  levels than would be possible with incandescent
  lighting.

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Solar Home System (Wiring and Mounting)

• An SHS also contains additional materials for
  mounting and connections.
• Metal frames are included to attach the PV
  Modules to a pole or roof.
• SHS components are connected by wires and contain
  switches for the lights.

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Questions?
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SIZING A SOLAR POWER ELECTRIC SYSTEM

• Three factors determine size
• Sunlight levels
• Determined by environment
• Power consumption
• Appliances
• Heating - A/C
• Water heater
• Desired energy contribution
• Cover all energy needs
• Cover partial energy needs

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SIZING A SOLAR POWER ELECTRIC SYSTEM

• Determine the yearly amount of energy you want
  produced by your SHS system in kWh per year.
• Divide this energy amount by 1750 kWh (the yearly
  output of a 1kW system), this gives you the size
  of the system needed (ex .5,1,2 kW system)

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Cost

• A very small system that would only handle a
  fraction of your electrical usage may cost only a
  few thousand dollars.
• A mid-sized system could cost between 18,000 and
  25,000 -- installation included -- and before
  any rebates are deducted.
• A large system could cost 40,000 and more before
  any rebates.

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Government Incentives

• Tax credits
• State grants
• State rebates
• Low interest loans
• Property tax exemptions
• Sales tax exemptions

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Government Incentives

• October 2 , 2002 - Washington, DC, USA
  Department of Energy Awards 1.5 Million for
  Solar Roof Grants
• Homeowners across the UK can now apply for a
  government grant to cover 50 of the costs of
  fitting solar panels to their roofs. (3,000
  grants are available)
• Some states such as California have rebates that
  cover up to 50 of the cost of the system for a
  MyGen system (or any qualifying PV system) which
  is tied to the electrical grid.
• DSIREUSA.ORG List of incentives

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The local electric utility

• More than 34 states now have laws requiring the
  electrical utilities in those states to allow PV
  systems to be connected to their grids.
• Unused energy can sometimes be sold to the
  utility.

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My House

• Bergen County Residential Customer
• Income 200,000 per year
• Electricity rate 10 cents per kWh
• Consume about 15,000 kWh per year
• Electric Bill 1,500 per year - 125 per month

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My Efficient House

• Could reduce consumption to 10,000 kWh per year.
• Electric bill would be 1,000 per year - 84 per
  month
• Electric bill would be 25,000 for 25 years.

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Kyocera Company Estimation

• Calculates estimated cost using predetermined
  data
• The pre-collected data is updated regularly and
  includes
• Electric rate schedules for your city or area
• Federal state income tax rates
• Federal, state utility economic incentives
• Local weather data
• Electric load profiles (you can use your own
  electric bill for specific information)
• PV system energy performance

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My House My-Gen 64 (Kyocera)

• Item My-Gen 64 6.4kW (50,000 before rebate)
• Item 75 per month (after 30,000 grant with a
  25 year loan 8 interest rate)
• Item 90 per month (After 25,000 grant )
• produce 10,000 kWh of electricity per year
• eliminate
• 16,000 lbs of CO2
• 44 lbs of SO2
• 30 lbs of NOX emissions in the first year

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My House - Calculations
Normal SHS (20k) SHS (25k) SHS (30K)
per year 1,000 800 1,000 1,200
per month 85 75 90 105
Electricty 10000kW 10000kW 10000kW 10000kW
CO2 16,000lb -16,000lb -16,000lb -16,000lb
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Conclusions

• As of now, I may be able to switch to solar power
  with a slight gain or slight loss depending on
  the amount of grant .
• However, as technology increases, solar prices
  fall, and electricity prices rise, this may
  become a more economical solution.
• I also greatly reduce the amount of harmful
  emissions by using solar power.

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Example3

• San Antonio, TX Residential Customer
• Income 80,000 per year
• Electric Bill 1,200 per year
• Item My-Gen 24 (19,000 before rebate)
• produce 4,300 kWh of electricity per year
• eliminate
• 5,000 lbs of CO2
• 21 lbs of SO2
• 13 lbs of NOX emissions in the first year
• My-Gen 64 (50,000 cost)
• produce 11,256 kWh of electricity per year
• (10,000 kW in New Jersey)
• eliminate
• 13,400 lbs of CO2
• 55 lbs of SO2
• 34 lbs of NOX emissions in the first year

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Example4

• Rumford, ME Residential Customer
• Income 80,000 per year
• Electric Bill 1,200 per year
• Item My-Gen 24 (5,000 before rebate)
• produce 3,800 kWh of electricity per year
• Eliminate
• 6,500 lbs of CO2 emissions in the first year
• 6 lbs of SO2
• 1 lbs of NOX emissions in the first year
• Item My-Gen 64 (50,000 before rebate)
• produce 10,000 kWh of electricity per year
• Eliminate
• 17,500 lbs of CO2
• 15 lbs of SO2
• 3 lbs of NOX emissions in the first year

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Questions?
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North Carolina State Universitys Solar House
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North Carolina State Universitys Solar House

• Opened in 1981.
• Serves as an educational and demonstration
  showcase for solar and energy-efficient
  technologies.
• Contains laboratories for solar research as well
  as information libraries.
• Provides information tours for those interested
  in solar power and energy efficiency.

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NCSU Solar House

• 2,000 Sq. ft house.
• Total heating bill less than 70 for entire
  winter.
• Features
• More than 250 solar and temp. measuring devices
• Centrally located sunspace
• Two thermal solar walls
• Solar hot water system
• Photovoltaic system (generates 3 kilowatts)
• Natural light fixtures
• Water source heat pump (back up Heat-A/C)
• Earth berming reduces winter heat loss
• Additional energy efficient features

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Upper Level
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Lower Level
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Outside

• Overhangs, shading sunscreens, shading structures
  for the summer.
• Earth berming on north and west lower walls.
• Insulating shutters on north facing windows.
• Solar powered security lights.

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Conclusions

• Solar power is a definite possibility for homes.
• Uses energy from sun to run appliances or charge
  batteries for later use.
• Is relatively expensive as of now, however, new
  technologies along with government incentives can
  greatly reduce the price.
• As the price falls and the price of conventional
  energy rises, this may become a more economical
  solution.
• It greatly reduces the amount of harmful
  emissions.

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Discussion

• Questions?
• What do you think of solar home systems?
• Would you consider using one in your home?
• Any drawbacks you can think of?
• Do you think it will become more popular in the
  future?