cee500 fall01 solar

Solar Energy: 

Solar Energy A Zero Emission Energy Source Prepared By: Min Jang Mike Hultgren Alyssa Lanier Josh Quast David Kraft Abby McDermott

Overview : 

Overview The Sun’s Energy History of Solar Energy Chemistry Types of Solar Cells and Examples Arguments against Solar Energy Arguments supporting Solar Energy Conclusion

Solar Spectrum: 

Solar Spectrum Energy in l l=Red = 1.7eV l=Blue = 2.7eV Energy needed for PV or PEC = 1.8 eV

Amount of Sun’s Energy Hitting US: 

Amount of Sun’s Energy Hitting US (kWh/d/m2) Harness 7-17% of this energy

Fuel Equivalents: 

Fuel Equivalents

How much sun do we need?: 

How much sun do we need? The average American home uses about 24 kWh of electricity per day. A 200 watt Photovoltaic array of six, 50 watt modules, will generate 1kWh in an “average” day.

History: 

History 1839-Edmund Becquerel discovers photovoltaic effect while working with electrolytic cell 1877- Photovoltaic effect observed in solid Selenium and first selenium cell produced 1883- First solar cells described 1904- Einstein published paper on photovoltaic effect 1916- Millikan provided experimental proof of photoelectric effect 1953- American scientist makes first theoretical efficiency calculations based on sun’s spectrum 1954- First demonstrations of solar cells 1955 First International Conference on Solar Energy

History (contd.): 

History (contd.) 1956- First thought of using solar cells for orbiting satellites 1962- First commercial telecommunications satellite launched 1973- “Solar One”, one of world’s first solar residences, constructed 1975- US Government initiates terrestrial solar power research and development 1977- Solar Energy Research Institute begins operation 1982- Volkswagen begins testing PV arrays on cars 1992- Solar power system installed at research facility on Antarctica 1996- World’s most advanced solar plane flies over Germany 1999- First successful balloon trip around world powered by solar cells

Photovoltaic Basic Mechanics: 

Photovoltaic Basic Mechanics Solar collectorphotovoltaic cell Absorbs sunlight Produces direct electric current Inverter, Controls Load Components

Photovoltaic Chemistry: 

Photovoltaic Chemistry Take Crystalline lattice of semiconductor (e.g. SiO2, TiO2) Dope lattice to give (+) or (-) electrons 1. Silicon Molecule 2. Doped Molecule

Photovoltaic Chemistry: 

Photovoltaic Chemistry Create Band Gap of Energy n-layer = (+) electron p-layer = (-) electron Amount of energy depends on semiconductor 1.1 eV = Si 1.43 eV = GaAs

Photovoltaic Chemistry: 

Photovoltaic Chemistry 4. Light energy adsorbed 5. If Adsorbed Energy > Band Gap Energy Then bump n-layer electron to p-layer

Photovoltaic Chemistry: 

Photovoltaic Chemistry 6. Force return of electron to n-layer through junction = Flow of Electrons = Electricity

Photoelectrochemical (PEC): 

Photoelectrochemical (PEC) 1. Similar to Photovoltaic = Flow of e- between: Electrolyte Solution & Semiconductor Organic Solution & Semiconductor 2. Also used to store energy = Split Water

PEC Chemistry: 

PEC Chemistry Place Semiconductor in electrolyte solution (n-layer type) Light energy bumps e- from semiconductor Excess (+) charge oxidizes reducing (R) agent in solution. Force return of e- to solution through junction Flow of e- electricity Return e- to solution, reduce oxidizing agent (Ox)

PEC Chemistry: 

PEC Chemistry

PEC to Store Energy: 

PEC to Store Energy Use movement of electrons to split water and store H2 and O2 H2 O2 H20 = Reduce Agent H+ = Ox Agent

Storage Technology: 

Storage Technology Batteries Homes and small businesses Hot water Thermal storage Homes and small businesses Fuel cells Chemical storage Automobiles

Types of Solar Cells: 

Types of Solar Cells Gallium Arsenide Cadium Telluride Copper Indium diselenide Efficiency

Options for Solar Array: 

Options for Solar Array Stand Alone System “Grid Tie” System Complete “Stand Alone” System “Hybrid” Solar Electric and Generator Combination System

Converting and Storing Solar Power: 

Converting and Storing Solar Power Inverter changes DC power to usable 120V AC power Charge Controller prevents batteries from overcharging Batteries storage Wiring

Arguments Against Solar Energy: 

Arguments Against Solar Energy Sunlight Availability Sunlight is necessary Different intensities of sun’s rays - effect efficiency Solar access protection Cost More expensive than conventional energy Can not be exclusive power source

Arguments Against Solar Energy: 

Arguments Against Solar Energy Efficiency Demand of energy exceeds production Solar landscaping Responsibilities Maintenance Knowledge of the system Insurance coverage Technology Advances

Arguments Supporting Solar Energy: 

Arguments Supporting Solar Energy Efficiency will improve with future development of technology As technology improves cost will decrease Ability to store energy for future use Environmentally friendly Fossils fuels are running out and another means of energy is necessary

California Solar Incentives: 

California Solar Incentives Alternative energy buy-down program Began September 1, 2000 and will continue for 5 years Subsidize PV rooftop systems Also includes small turbines and fuel cells

Million Solar Roofs: 

Million Solar Roofs U.S. DOE project to install a million solar roofs across the country by 2010 The federal government is working with manufacturers and electric companies to make this technology affordable Over 2000 solar energy systems have been installed on government buildings alone

CO2 Emission Reduction: 

CO2 Emission Reduction Million Solar Roofs Reduce CO2 by an equivalent of 850,000 cars/year Prevent 34 tons of green house gas in each solar roof’s lifetime

Cost Improvement: 

Cost Improvement

Summary: 

Summary No CO2 emission Technology is constantly improving Becoming more feasible to implement Permanent energy source

Questions: 

Questions

References: 

References http://www.aurora.crest.org/pv/cells/types/#single crystal silicon.html http://www.eren.doe.gov/millionroofs/ http://www.eren.doe.gov/sdarbuildings/moreinfo.html http://www-formal.stanford.ude/jmc/progress/solar.html http://www.geocities.com/Athens/Parthenon/2838/hotstuff.html Goswami, D. Yogi (2001). Advances in solar energy: an annual review of research and development, (vol. 14). Boulder, Colorado: American Solar Energy Society, Inc. http://www.ise.fhg.de/ http://acre.murdoch.edu.au/refiles/pv/text.html Norton, Brian. (1992). Solar energy thermal technology. Berlin: Springer-Verlag. http://www.pvpower.com/pvhistory.html http://www.shell.com/rw-br/content/0,6126,30451-51325,00.html http://www.solarexpert.com http://www.solarserver.de/wissen/photovoltaik-e.html#diff

References: 

References 14. http://www.wisconsun.org 15. Yoshihiro, Nakato. Photoelectrochemical Cells. Wiley Encyclopedia of Electrical and Electronics Engineering Online. www.intersciencewiley.com:83/eeee/30/3030/W.3030