Solar Energy
Solar Energy Systems
Matt AldemanSenior Energy Analyst
Center for Renewable EnergyIllinois State University
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SOLAR ENERGY OVERVIEW
1) Types of Solar Power Plants2) Describing the Solar Resources3) Photovoltaic (PV) System Components4) Photovoltaic (PV) System Mounting Types
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Solar Energy• Types of “Solar Energy”:
– Solar Thermal• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Photovoltaic Effect
Photovoltaic Panel Components
• Cell• Module • Array
Source: US DOE
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Solar Energy
• Types of “Solar Energy”:– Solar Thermal
• Residential Systems (hot water)• Utility-scale trough collectors• Power Towers• Solar Chimneys
– Solar Photovoltaic• Monocrystalline• Polycrystalline• Amorphous Silicon (thin-film)• Multi-Junction• Concentrated PV
Path of the Sun• Actually, path of the Earth• Two motions of interest:1) yearly rotation of Earth about the Sun. The Earth rotates in a circle (actually a slight ellipse) around the Sun. The perimeter of this ellipse defines the ecliptic plane
2) daily rotation about Earth’s axis. Earth’s axis is 23.5 degrees tilted from the ecliptic plane. The equator of the Earth defines the equatorial plane
Ecliptic vs Equatorial planes
Ecliptic plane Equatorial plane
Angle between ecliptic plane and equatorial plane is always 23.5°
Solstices, Equinox• Summer Solstice: Solar declination is at its maximum (+23.5°).
Days are longer than nights in Northern Hemisphere. All points south of Antarctic Circle are in total darkness. Sun is at zenith (straight up) at noon for locations on Tropic of Cancer.
• Equinox (Spring, Fall): Every location on Earth has equal length day and nights. Sun is at zenith at noon on the equator. Sun rises due east and sets due west across the globe.
• Winter Solstice: Minimum solar declination (‐23.5°). Days are shorter than nights in the Northern Hemisphere. All points north of the Arctic Circle are in total darkness. Sun is at zenith at noon for locations on Tropic of Capricorn.
Where is the sun?• Azimuth Angle: The horizontal angle between a
reference direction (typically south) and the direction that a solar array faces
• Solar altitude angle: The vertical angle between the horizon and the sun (how high is the sun in the sky?)
• Tilt angle (for solar arrays): vertical angle between the horizontal and the plane of the solar array
Sun Paths
U.S. Solar Resources
Worldwide Solar Resources
Absorbed by O3, CO2, H2O
Scattered by particles
Atmospheric Effects
10-20% diffuseclear day
Atmospheric Effects
100% diffusecloudy day
Atmospheric Effects
Flat plate collectors use diffuse and direct radiation
Concentrating collectors use only direct radiation
Irradiance is a measure of solar power
Sunrise SunsetNoon
1000 W/m2 = peak sun
1000
500
Insolation is the solar energy in 1 day
Sunrise SunsetNoon
4.5 kWh/m2 /day
1000
500 4.5 peak sun hours
North South
East
West
Sun path at equinoxesSun path at
summer solsticeSun path at winter
solstice
Solar Window
Photovoltaic panels are rated at 1 peak sun (1000W/m2)
200 W x 4.5 sun hours/day
900 Wh or .9 kWh of energy/day
200W
How much electric energy is produced by a PV Module?
PV Market Segments
• Residential Market: <30kW– Homeowners
• Commercial Scale: 30 – 300 kW– Factories and Retail outlets
• Utility Scale: >300 kW– Subject to same regulations as
power plant contruction/operation
Solar Energy Annual Growth
System Types
1) Grid Tie2) Grid Tie with Battery Backup3) Off-Grid
Home Power, December 2011, p.60
Grid Tie SystemsMost systems installed in the US are grid tie.
Grid tie inverters use high voltage PV series strings for simplified wiring.
Grid tie systems cost $6-8 per watt installed.
The system does not have to support the entire load, keeping costs low.
The system cannot function when the grid is disrupted.
http://256.com/solar/
Grid tie inverter
To grid
http://256.com/solar/
Grid tie inverter
To grid
Net Metering
Stand Alone (Off Grid) SystemsBattery based inverters use low voltage PV wiring. This is more complex and expensive.
Off grid systems cost $10-12 per watt installed.
The system must support the entire load, usage must be carefully monitored
Batteries require maintenance and must be replaced.
Home Power, April/May 2010. p. 82
Off grid systems require extra equipment.• Battery bank• Charge controller• Generator backup• Transfer switch
Roof Mount SystemsMost systems are installed from the top
Clips are used to mount panels to railsRails are bolted to rafters
Roof Mount SystemsModules are close to roof for neat appearance
Flashing guards against water damage
Panels get hot and performance is reduced
Many of these homes have no south facing
roof slopes.
Crystalline PV modules mounted on steel roof
http://www.nrel.gov/data/pix/Jpegs/17843.jpg
PV modules mounted on standing seam steel roof
Special clips are available to mount directly to seams
http://www.coolflatroof.com/ib-solar-roof.php#intro
PV integrated with cool roof membraneGood application for California because many roofs cannot support much extra weight
http://www.nrel.gov/data/pix/Jpegs/13455.jpg
Rack mounted and ballasted on flat roofs
Inexpensive and easy to install, no roof penetrations
Adds extra weight to roof
2.4 kW PV array, Turner Hall, Illinois State University
Ground Mounts for Large Scale PV
Single Axis Trackers on N-S Axis
Single Axis Azimuth Trackers
Single Axis Azimuth Trackers
Dual Axis Trackers
Up to 30% more energy compared to fixed mounted PV
Questions?
Matt AldemanSenior Energy Analyst
Center for Renewable EnergyIllinois State University
[email protected](309) 438-1440