Solar Powered Housing Darryl Birtwistle Energy, Society, and Climate November 6, 2002

Topics of Discussion Basic Concept. Basic Concept. What’s required for an efficiently solar powered house. What’s required for an efficiently solar 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 Concept Takes energy from the sun and converts it into electrically energy. Takes energy from the sun and converts it into electrically energy. This energy is used to run appliances or charge a battery. 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. The battery can be used to run appliances when the solar panels are not producing energy.

What’s required? Reduce amount of energy consumed. Reduce amount of energy consumed. –Efficient house design. –Efficient energy usage. Use of effective solar power technology. Use of effective solar power technology.

Effective House Design Properly sealed house Properly sealed house Properly insulation Properly insulation Proper window design (passive heating) Proper window design (passive heating) Proper materials Proper materials Efficient air infiltration Efficient air infiltration

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

Photovoltaic Cells

Photovoltaic take advantage of the fact that light can knock electrons out of atoms of certain substances. Photovoltaic take advantage of the fact that light can knock electrons out of atoms of certain substances. Cells consist of two silicon layers. Cells consist of two silicon layers. Layer facing the sun is positively charged while layer beneath is negatively charged. 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). 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). The electricity is then sent through an inverter to convert it to an alternating current (AC – Flowing both ways).

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.

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

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

Photovoltaic Modules Modules are measured in units of "peak watts“ (Wp). 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). 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. "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. North America averages 3 to 4 peak sun hours per day in summer. Equatorial regions can reach above 6 peak sunlight hours. Equatorial regions can reach above 6 peak sunlight hours.

Solar Home System Each SHS includes a PV module, a battery, a charge controller, an inverter, wiring, fluorescent lights, and outlets for other appliances. 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. 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 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 four 7W lamps each evening several hours of television. several hours of television.

Solar Home System

Solar Home System (Module) Most efficient orientation of a solar module is at true south. Most efficient orientation of a solar module is at true south. To determine, divide the span of time between sunrise and sunset in half. 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. 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.

Solar Home System (Module) Your lattitude offers the best year-round position. 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 winter months. +15 degrees will give you more insolation during the summer months. +15 degrees will give you more insolation during the summer months.

Solar Home System (Module)

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

Solar Home System (Charge Controller) Controls the flow of electricity between the module, battery, and the loads. 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. 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. 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. 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. Indicator lights on the controller display the relative state of charge of the battery.

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

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

Solar Home System (Wiring and Mounting) An SHS also contains additional materials for mounting and connections. An SHS also contains additional materials for mounting and connections. Metal frames are included to attach the PV Modules to a pole or roof. 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. SHS components are connected by wires and contain switches for the lights.

Questions?

SIZING A SOLAR POWER ELECTRIC SYSTEM Three factors determine size: Three factors determine size: –Sunlight levels Determined by environment Determined by environment –Power consumption Appliances Appliances Heating - A/C Heating - A/C Water heater Water heater –Desired energy contribution Cover all energy needs Cover all energy needs Cover partial energy needs Cover partial energy needs

SIZING A SOLAR POWER ELECTRIC SYSTEM Determine the yearly amount of energy you want produced by your SHS system in kWh per year. 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) 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)

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

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

Government Incentives October 2, Washington, DC, USA: Department of Energy Awards $1.5 Million for Solar Roof Grants October 2, 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) 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. 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 DSIREUSA.ORG – List of incentives

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

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

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

Kyocera Company Estimation Calculates estimated cost using predetermined data Calculates estimated cost using predetermined data The pre-collected data is updated regularly and includes: 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

My House: My-Gen 64 (Kyocera) Item My-Gen 64 – 6.4kW ($50,000 before rebate) 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 $75 per month (after $30,000 grant $ 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 year produce 10,000 kWh of electricity per year eliminate eliminate –16,000 lbs of CO2 –44 lbs of SO2 –30 lbs of NOX emissions in the first year

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 Electricty10000kW10000kW10000kW10000kW CO216,000lb-16,000lb-16,000lb-16,000lb

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

Example3 San Antonio, TX – Residential Customer San Antonio, TX – Residential Customer Income – $80,000 per year Income – $80,000 per year Electric Bill $1,200 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 5,000 lbs of CO2 21 lbs of SO2 21 lbs of SO2 13 lbs of NOX emissions in the first year 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) (10,000 kW in New Jersey) –eliminate 13,400 lbs of CO2 13,400 lbs of CO2 55 lbs of SO2 55 lbs of SO2 34 lbs of NOX emissions in the first year 34 lbs of NOX emissions in the first year

Example4 Rumford, ME – Residential Customer Rumford, ME – Residential Customer Income – $80,000 per year Income – $80,000 per year Electric Bill $1,200 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 6,500 lbs of CO2 emissions in the first year 6 lbs of SO2 6 lbs of SO2 1 lbs of NOX emissions in the first year 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 17,500 lbs of CO2 15 lbs of SO2 15 lbs of SO2 3 lbs of NOX emissions in the first year 3 lbs of NOX emissions in the first year

Questions?

North Carolina State University’s Solar House

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

NCSU Solar House 2,000 Sq. ft house. 2,000 Sq. ft house. Total heating bill less than $70 for entire winter. Total heating bill less than $70 for entire winter. Features: 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

Upper Level

Lower Level

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

Conclusions Solar power is a definite possibility for homes. Solar power is a definite possibility for homes. Uses energy from sun to run appliances or charge batteries for later use. 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. 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. 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. It greatly reduces the amount of harmful emissions.

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