Solar Powered HousingSolar Powered Housing

Darryl BirtwistleDarryl Birtwistle

Energy, Society, and ClimateEnergy, Society, and Climate

November 6, 2002November 6, 2002

Topics of DiscussionTopics of Discussion

• Basic Concept.Basic Concept.

• What’s required for an efficiently solar What’s required for an efficiently solar powered house.powered house.

• Basic technology of solar power.Basic technology of solar power.

• Solar home systems (different parts).Solar home systems (different parts).

• Determining cost and size.Determining cost and size.

• How solar power can benefit you.How solar power can benefit you.

• Examine an efficient solar house. Examine an efficient solar house.

Basic ConceptBasic Concept

• Takes energy from the sun and Takes energy from the sun and converts it into electrically energy.converts it into electrically energy.

• This energy is used to run appliances This energy is used to run appliances or charge a battery.or charge a battery.

• The battery can be used to run The battery can be used to run appliances when the solar panels are appliances when the solar panels are not producing energy.not producing energy.

What’s required?What’s required?

• Reduce amount of energy Reduce amount of energy consumed.consumed.– Efficient house design.Efficient house design.– Efficient energy usage.Efficient energy usage.

• Use of effective solar power Use of effective solar power technology.technology.

Effective House DesignEffective House Design

• Properly sealed houseProperly sealed house

• Properly insulationProperly insulation

• Proper window design (passive Proper window design (passive heating)heating)

• Proper materialsProper materials

• Efficient air infiltrationEfficient air infiltration

Efficient Energy UsageEfficient Energy Usage

• Efficient appliancesEfficient appliances– EnergystarEnergystar

• Energy conservativeEnergy conservative– Turning off lights.Turning off lights.– Turning down A/C.Turning down A/C.– Keeping windows and doors closed.Keeping windows and doors closed.

Photovoltaic CellsPhotovoltaic Cells

Photovoltaic CellsPhotovoltaic Cells• Photovoltaic take advantage of the fact that Photovoltaic take advantage of the fact that

light can knock electrons out of atoms of light can knock electrons out of atoms of certain substances.certain substances.

• Cells consist of two silicon layers.Cells consist of two silicon layers.• Layer facing the sun is positively charged Layer facing the sun is positively charged

while layer beneath is negatively charged.while layer beneath is negatively charged.• Sun hits the cell and knocks electrons from Sun hits the cell and knocks electrons from

positively charged surface to the negatively positively charged surface to the negatively charged surface, creating an direct electric charged surface, creating an direct electric current (DC - flowing one way).current (DC - flowing one way).

• The electricity is then sent through an The electricity is then sent through an inverter to convert it to an alternating inverter to convert it to an alternating current (AC – Flowing both ways).current (AC – Flowing both ways).

Photovoltaic CellPhotovoltaic 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.

Photovoltaic CellsPhotovoltaic Cells

• Two main types of silicon cells are crystalline Two main types of silicon cells are crystalline and thin-film.and thin-film.

• Crystalline:Crystalline:– Highly efficient (20%), the production process is Highly efficient (20%), the production process is

expensive. (lifetime of over 20 yrs)expensive. (lifetime of over 20 yrs)

• Thin-film:Thin-film:– Lower efficiency, less expensive. (lifetime of at least Lower efficiency, less expensive. (lifetime of at least

10 years) 10 years)

• More efficient models are being developed More efficient models are being developed (%40)(%40)

Photovoltaic ModulesPhotovoltaic Modules

• Photovoltaic cells produce little Photovoltaic cells produce little energy by themselves.energy by themselves.

• Photovoltaic cells are connected to Photovoltaic cells are connected to form modules or panels that can form modules or panels that can produce a large amount of energy.produce a large amount of energy.

• Combing cells can produce anywhere Combing cells can produce anywhere from a few milliwatts (calculator) to from a few milliwatts (calculator) to several megawatts. several megawatts.

Photovoltaic ModulesPhotovoltaic Modules• Modules are measured in units of "peak Modules are measured in units of "peak

watts“ (Wp).watts“ (Wp).

• This refers to the power output of the This refers to the power output of the module under "peak sun" conditions (1000 module under "peak sun" conditions (1000 Watts per square meter).Watts per square meter).

• "Sun hours," or "insolation," refers to the "Sun hours," or "insolation," refers to the average number of peak sun hours.average number of peak sun hours.

• North America averages 3 to 4 peak sun North America averages 3 to 4 peak sun hours per day in summer. hours per day in summer.

• Equatorial regions can reach above 6 peak Equatorial regions can reach above 6 peak sunlight hours. sunlight hours.

Solar Home SystemSolar Home System

• Each SHS includes a PV module, a battery, a Each SHS includes a PV module, a battery, a charge controller, an inverter, wiring, charge controller, an inverter, wiring, fluorescent lights, and outlets for other fluorescent lights, and outlets for other appliances.appliances.

• The size of the SHS (20Wp, 35Wp, 50Wp) The size of the SHS (20Wp, 35Wp, 50Wp) determines the amount of energy produced. determines the amount of energy produced.

• A standard small SHS can operate several A standard small SHS can operate several lights, a black-and-white television, a radio lights, a black-and-white television, a radio or cassette player, and a small fan.or cassette player, and a small fan.– A 35 Wp SHS A 35 Wp SHS

• four 7W lamps each eveningfour 7W lamps each evening• several hours of television. several hours of television.

Solar Home SystemSolar Home System

Solar Home System Solar Home System (Module)(Module)• Most efficient orientation of a solar Most efficient orientation of a solar

module is at true south. module is at true south.

• To determine, divide the span of To determine, divide the span of time between sunrise and sunset in time between sunrise and sunset in half.half.

• The angle of the solar array can be The angle of the solar array can be anywhere from your lattitude plus 15 anywhere from your lattitude plus 15 degrees to lattitude minus 15 degrees to lattitude minus 15 degrees for a yearly fixed mount degrees for a yearly fixed mount position. position.

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

• Your lattitude offers the best year-Your lattitude offers the best year-round position. round position.

• -15 degrees will give you more -15 degrees will give you more insolation during winter months. insolation during winter months.

• +15 degrees will give you more +15 degrees will give you more insolation during the summer insolation during the summer months. months.

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

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

• Inverter is used to transform the Inverter is used to transform the direct current (D/C) to an alternating direct current (D/C) to an alternating current (A/C).current (A/C).

• Different inverters can provide Different inverters can provide different voltages and different different voltages and different efficiencies.efficiencies.

Solar Home System Solar Home System (Charge (Charge Controller)Controller)

• Controls the flow of electricity between the Controls the flow of electricity between the module, battery, and the loads. module, battery, and the loads.

• Prevents battery damage by ensuring that the Prevents battery damage by ensuring that the battery is operating within its normal charge battery is operating within its normal charge levels. levels.

• If the charge level in the battery falls below a If the charge level in the battery falls below a certain level, a "low voltage disconnect (LVD) will certain level, a "low voltage disconnect (LVD) will cut the current to the loads, to prevent further cut the current to the loads, to prevent further discharge. discharge.

• Likewise, it will also cut the current from the Likewise, it will also cut the current from the module in cases of overcharging. module in cases of overcharging.

• Indicator lights on the controller display the Indicator lights on the controller display the relative state of charge of the battery. relative state of charge of the battery.

Solar Home System Solar Home System (Battery)(Battery)• An electrochemical storage battery is used An electrochemical storage battery is used

to store the electricity converted by the to store the electricity converted by the solar module. solar module.

• During the day, electricity from the During the day, electricity from the module charges the storage battery. module charges the storage battery.

• During the evening, the battery is During the evening, the battery is discharged to power lights and other discharged to power lights and other appliances. appliances.

• Batteries are typically sized to provide Batteries are typically sized to provide several days of electricity in the event that several days of electricity in the event that overcast weather prevents recharging.overcast weather prevents recharging.

Solar Home System Solar Home System (Lighting)(Lighting)

• Compact fluorescent light bulbs as Compact fluorescent light bulbs as well as fluorescent tube lights are well as fluorescent tube lights are used for lighting. used for lighting.

• An SHS normally includes two to six An SHS normally includes two to six lights.lights.

• An SHS can provide substantially An SHS can provide substantially higher lighting levels than would be higher lighting levels than would be possible with incandescent lighting. possible with incandescent lighting.

Solar Home System Solar Home System (Wiring and (Wiring and Mounting)Mounting)

• An SHS also contains additional An SHS also contains additional materials for mounting and materials for mounting and connections. connections.

• Metal frames are included to attach Metal frames are included to attach the PV Modules to a pole or roof. the PV Modules to a pole or roof.

• SHS components are connected by SHS components are connected by wires and contain switches for the wires and contain switches for the lights. lights.

Questions?Questions?

SIZING A SOLAR POWER ELECTRIC SIZING A SOLAR POWER ELECTRIC

SYSTEMSYSTEM • Three factors determine size:Three factors determine size:

– Sunlight levelsSunlight levels•Determined by environmentDetermined by environment

– Power consumptionPower consumption•AppliancesAppliances

•Heating - A/CHeating - A/C

•Water heaterWater heater

– Desired energy contributionDesired energy contribution•Cover all energy needsCover all energy needs

•Cover partial energy needsCover partial energy needs

SIZING A SOLAR POWER ELECTRIC SIZING A SOLAR POWER ELECTRIC SYSTEMSYSTEM

• Determine the yearly amount of Determine the yearly amount of energy you want produced by your energy you want produced by your SHS system in kWh per year.SHS system in kWh per year.

• Divide this energy amount by 1750 Divide this energy amount by 1750 kWh (the yearly output of a 1kW kWh (the yearly output of a 1kW system), this gives you the size of system), this gives you the size of the system needed (ex: .5,1,2 kW the system needed (ex: .5,1,2 kW system)system)

CostCost• A very small system that would only A very small system that would only

handle a fraction of your electrical handle a fraction of your electrical usage may cost only a few thousand usage may cost only a few thousand dollars.dollars.

• A mid-sized system could cost A mid-sized system could cost between $18,000 and $25,000 -- between $18,000 and $25,000 -- installation included -- and before installation included -- and before any rebates are deducted.any rebates are deducted.

• A large system could cost $40,000 A large system could cost $40,000 and more before any rebates. and more before any rebates.

Government IncentivesGovernment Incentives

• Tax creditsTax credits

• State grantsState grants

• State rebatesState rebates

• Low interest loansLow interest loans

• Property tax Property tax exemptionsexemptions

• Sales tax exemptionsSales tax exemptions

Government IncentivesGovernment Incentives• October 2 , 2002 - Washington, DC, USA: October 2 , 2002 - Washington, DC, USA:

Department of Energy Awards $1.5 Million Department of Energy Awards $1.5 Million for Solar Roof Grantsfor Solar Roof Grants

• Homeowners across the UK can now apply Homeowners across the UK can now apply for a government grant to cover 50% of for a government grant to cover 50% of the costs of fitting solar panels to their the costs of fitting solar panels to their roofs. (3,000 grants are available)roofs. (3,000 grants are available)

• Some states such as California have Some states such as California have rebates that cover up to 50% of the cost of rebates that cover up to 50% of the cost of the system for a MyGen system (or any the system for a MyGen system (or any qualifying PV system) which is tied to the qualifying PV system) which is tied to the electrical grid.electrical grid.

• DSIREUSA.ORG – List of incentivesDSIREUSA.ORG – List of incentives

The local electric utilityThe local electric utility

• More than 34 states now have laws More than 34 states now have laws requiring the electrical utilities in requiring the electrical utilities in those states to allow PV systems to those states to allow PV systems to be connected to their grids.be connected to their grids.

• Unused energy can sometimes be Unused energy can sometimes be sold to the utility. sold to the utility.

My HouseMy House

• Bergen County – Residential Bergen County – Residential CustomerCustomer

• Income – $200,000 per yearIncome – $200,000 per year

• Electricity rate 10 cents per kWhElectricity rate 10 cents per kWh

• Consume about 15,000 kWh per yearConsume about 15,000 kWh per year

• Electric Bill $1,500 per year - $125 Electric Bill $1,500 per year - $125 per monthper month

My Efficient HouseMy Efficient House

• Could reduce consumption to 10,000 Could reduce consumption to 10,000 kWh per year.kWh per year.

• Electric bill would be $1,000 per year Electric bill would be $1,000 per year - $84 per month - $84 per month

• Electric bill would be $25,000 for 25 Electric bill would be $25,000 for 25 years.years.

Kyocera Company Kyocera Company EstimationEstimation• Calculates estimated cost using Calculates estimated cost using

predetermined datapredetermined data• The pre-collected data is updated regularly The pre-collected data is updated regularly

and includes:and includes:– Electric rate schedules for your city or area Electric rate schedules for your city or area – Federal & state income tax rates Federal & state income tax rates – Federal, state & utility economic incentivesFederal, state & utility economic incentives– Local weather data Local weather data – Electric load profiles (you can use your own Electric load profiles (you can use your own

electric bill for specific information) electric bill for specific information) – PV system energy performancePV system energy performance

My House: My-Gen 64 My House: My-Gen 64 (Kyocera)(Kyocera)• Item My-Gen 64 – 6.4kW ($50,000 before Item My-Gen 64 – 6.4kW ($50,000 before

rebate)rebate)• Item $75 per month (after $30,000 grant $ Item $75 per month (after $30,000 grant $

with a 25 year loan – 8% interest rate)with a 25 year loan – 8% interest rate)• Item $90 per month (After $25,000 grant Item $90 per month (After $25,000 grant

$)$)• produce 10,000 kWh of electricity per yearproduce 10,000 kWh of electricity per year• eliminateeliminate

– 16,000 lbs of CO216,000 lbs of CO2– 44 lbs of SO244 lbs of SO2– 30 lbs of NOX emissions in the first year30 lbs of NOX emissions in the first year

My House - CalculationsMy House - Calculations

NormalNormal SHS SHS (20k)(20k)

SHS SHS (25k)(25k)

SHS SHS (30K)(30K)

$ per $ per yearyear

$1,000$1,000 $800$800 $1,000$1,000 $1,200$1,200

$ per $ per monthmonth

$85$85 $75$75 $90$90 $105$105

ElectrictElectrictyy

10000k10000kWW

10000k10000kWW

10000k10000kWW

10000kW10000kW

CO2CO2 16,000l16,000lbb

--16,000l16,000lbb

--16,000l16,000lbb

-16,000lb-16,000lb

ConclusionsConclusions

• As of now, I may be able to switch to solar As of now, I may be able to switch to solar power with a slight gain or slight loss power with a slight gain or slight loss depending on the amount of grant $.depending on the amount of grant $.

• However, as technology increases, solar However, as technology increases, solar prices fall, and electricity prices rise, this prices fall, and electricity prices rise, this may become a more economical solution.may become a more economical solution.

• I also greatly reduce the amount of I also greatly reduce the amount of harmful emissions by using solar power.harmful emissions by using solar power.

Example3Example3• San Antonio, TX – Residential CustomerSan Antonio, TX – Residential Customer• Income – $80,000 per yearIncome – $80,000 per year• Electric Bill $1,200 per yearElectric Bill $1,200 per year

– Item My-Gen 24 ($19,000 before rebate)Item My-Gen 24 ($19,000 before rebate)– produce 4,300 kWh of electricity per yearproduce 4,300 kWh of electricity per year – eliminate eliminate

• 5,000 lbs of CO2 5,000 lbs of CO2 • 21 lbs of SO221 lbs of SO2• 13 lbs of NOX emissions in the first year13 lbs of NOX emissions in the first year

– My-Gen 64 ($50,000 cost)My-Gen 64 ($50,000 cost)– produce 11,256 kWh of electricity per year produce 11,256 kWh of electricity per year

• (10,000 kW in New Jersey) (10,000 kW in New Jersey) – eliminate eliminate

• 13,400 lbs of CO2 13,400 lbs of CO2 • 55 lbs of SO255 lbs of SO2• 34 lbs of NOX emissions in the first year34 lbs of NOX emissions in the first year

Example4Example4• Rumford, ME – Residential CustomerRumford, ME – Residential Customer• Income – $80,000 per yearIncome – $80,000 per year• Electric Bill $1,200 per yearElectric Bill $1,200 per year

– Item My-Gen 24 ($5,000 before rebate)Item My-Gen 24 ($5,000 before rebate)– produce 3,800 kWh of electricity per yearproduce 3,800 kWh of electricity per year– EliminateEliminate

• 6,500 lbs of CO2 emissions in the first year6,500 lbs of CO2 emissions in the first year• 6 lbs of SO26 lbs of SO2• 1 lbs of NOX emissions in the first year1 lbs of NOX emissions in the first year

– Item My-Gen 64 ($50,000 before rebate)Item My-Gen 64 ($50,000 before rebate)– produce 10,000 kWh of electricity per yearproduce 10,000 kWh of electricity per year– Eliminate Eliminate

• 17,500 lbs of CO217,500 lbs of CO2• 15 lbs of SO215 lbs of SO2• 3 lbs of NOX emissions in the first year3 lbs of NOX emissions in the first year

Questions concerning Questions concerning non-fossil methods of non-fossil methods of energy procurementenergy procurement??

North Carolina State North Carolina State University’s Solar HouseUniversity’s Solar House

North Carolina State North Carolina State University’s Solar HouseUniversity’s Solar House• Opened in 1981.Opened in 1981.

• Serves as an educational and Serves as an educational and demonstration showcase for solar and demonstration showcase for solar and energy-efficient technologies.energy-efficient technologies.

• Contains laboratories for solar Contains laboratories for solar research as well as information research as well as information libraries.libraries.

• Provides information tours for those Provides information tours for those interested in solar power and energy interested in solar power and energy efficiency.efficiency.

NCSU Solar HouseNCSU Solar House• 2,000 Sq. ft house.2,000 Sq. ft house.• Total heating bill less than $70 for entire Total heating bill less than $70 for entire

winter.winter.• Features:Features:

– More than 250 solar and temp. measuring More than 250 solar and temp. measuring devicesdevices

– Centrally located sunspace Centrally located sunspace – Two thermal solar wallsTwo thermal solar walls– Solar hot water systemSolar hot water system– Photovoltaic system (generates 3 kilowatts)Photovoltaic system (generates 3 kilowatts)– Natural light fixturesNatural light fixtures– Water source heat pump (back up Heat-A/C)Water source heat pump (back up Heat-A/C)– Earth berming – reduces winter heat lossEarth berming – reduces winter heat loss– Additional energy efficient featuresAdditional energy efficient features

Upper LevelUpper Level

Lower LevelLower Level

OutsideOutside

• Overhangs, shading sunscreens, Overhangs, shading sunscreens, shading structures for the summer.shading structures for the summer.

• Earth berming on north and west Earth berming on north and west lower walls.lower walls.

• Insulating shutters on north facing Insulating shutters on north facing windows.windows.

• Solar powered security lights.Solar powered security lights.

ConclusionsConclusions

• Solar power is a definite possibility for Solar power is a definite possibility for homes.homes.

• Uses energy from sun to run appliances or Uses energy from sun to run appliances or charge batteries for later use.charge batteries for later use.

• Is relatively expensive as of now, however, Is relatively expensive as of now, however, new technologies along with government new technologies along with government incentives can greatly reduce the price.incentives can greatly reduce the price.

• As the price falls and the price of As the price falls and the price of conventional energy rises, this may conventional energy rises, this may become a more economical solution.become a more economical solution.

• It greatly reduces the amount of harmful It greatly reduces the amount of harmful emissions. emissions.

DiscussionDiscussion

• Questions?Questions?

• What do you think of solar home What do you think of solar home systems?systems?

• Would you consider using one in your Would you consider using one in your home?home?

• Any drawbacks you can think of?Any drawbacks you can think of?

• Do you think it will become more Do you think it will become more popular in the future?popular in the future?