Solar Energy
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Transcript of Solar Energy
Solar Energy
Solar energy has been an under-achiever
renewable sources
(non-nuclear)8%
wind0.5%
biomass 38%
hydroelectric 55 %
geothermal5%
solar1%
nuclear electric8%
coal22%
petroleum39% natural gas
23%
Source: U.S. Department of Energy
http://symposium2011.serdp-estcp.org/Technical-Sessions/3C
• 2500+ years – Passive – take advantage of ambient conditions
• 250+ years– Active Loop – capture, store, & deliver thermal
energy• 50+ years
– Photovoltaics – convert sunlight into electricity• 25+ years
– Hybrid Systems - concentrating collectors & others
Solar Energy Has A Long History
Passive solar collectors can be as simple as a house designed to take advantage of daylighting.
Passive solar heating recognizes the seasonal position of the sun.
Passive Day Lighting System• tracking dish to collect
sunlight• visible spectrum
transmitted using fiber optics
• packaged like a fluorescent light
• commercialization underway by Oak Ridge Lab
Active loops capture, store, and distribute heat.
Subtle details influence energy recovery for active loops
Photovoltaics capture, store, and distribute electricity.
How does a photovoltaic cell work?
http://science.nasa.gov/headlines/y2002/solarcells.htm
Optimum Mounting Angle
• Solar tracking systems improve overall efficiency up to 30% by keeping panels perpendicular to the sun.
• A fixed panel set at the same angle as the latitude of the site will receive the maximum annual solar radiation.
• If the load demand is high in the winter (northern hemisphere), set the panel tilt at latitude plus 15°.
• If the load demand is higher in the summer (northern hemisphere) set the array tilt angle at latitude minus 15°.
Solana 280 MW CSP plant in Arizona3 square miles of mirrors
Solar Energy Influenced by:
• atmospheric conditions• geographic location• time of day• pollution• season
Solar energy is impressive on sunny days…
…but there’s not much solar energy on cloudy days
Solar energy
changes seasonally
Sizing a Photovoltaic Array
daily energy requirements (kW-hr)/dayArray Size in kW =
Electric Loads
How much solar energy is available?
Average sunshine hours (hr/day)
Quantifying Home Electric Loads• Search using some of the following terms
– Residential– Electric– Calculator
• http://www.nhec.com/residential_energycalculators.php• http://www.tampaelectric.com/TEHMEnergySaversCalc.html
Web-Based PV Array Sizing
• Combine the power of – Mapping programs– PV sizing algorithms– Satellite-based weather data– Databases of rebates, tax credits, and other
incentives• http://www.nrel.gov/eis/imby/
Solar energy challenges
• Better methods of energy storage
• Cheaper manufacturing methods
• Better installation techniques
• Higher efficiency
Is solar energy a viable option?
pro’s• free, renewable, and
non-polluting• provides day-
lighting, heat, & electricity
• low maintenance• independence
con’s• more expensive
than conventional power
• energy source fluctuatesmust evaluate
case-by-case