1 Class 18 Solar Energy Many kinds of Solar Energy available to us With different benefits and costs Solar can heat and produce electricity, and dry things out (desiccant – to be used for refrigeration) http://www.eere.energy.gov/consumer/your_home/designing_remodeling/index.cfm/mytopic=10270 D. Long, PSc 320 2008 Summer or Winter? 2 x 23.5º = 47º Solar Thermal: For heated water or circulated in house Concentrated Solar Power: CSP Photovoltaics… 4 kinds we’ll address 1) Single Crystal Silicon – Expensive, not used much anymore 2) Polycrystalline Silicon – Most Popular 3) Thin Films – Up and Coming 4) HEPV Triple Junction Gallium Arsenide: >40%. $50,000 / m 2 … Used with Solar Concentrators “It takes more energy to make the cells than they produce in their lifetime” - No, Energy payback time ~ 1.5 years - Financial payback time ~ 7 years... Competitive?
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Class 18 Solar Energy
Many kinds of Solar Energy available to us With different benefits and costs Solar can heat and produce electricity, and dry things out (desiccant – to be used for refrigeration)
Solar Thermal: For heated water or circulated in house Concentrated Solar Power: CSP
Photovoltaics… 4 kinds we’ll address 1) Single Crystal Silicon – Expensive, not used much anymore 2) Polycrystalline Silicon – Most Popular 3) Thin Films – Up and Coming 4) HEPV Triple Junction Gallium Arsenide: >40%.
$50,000 / m2 … Used with Solar Concentrators “It takes more energy to make the cells than they produce in their lifetime”
- No, Energy payback time ~ 1.5 years - Financial payback time ~ 7 years... Competitive?
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41% achieved in laboratory Photosynthesis?
Efficiency: 0.3 % Combustion is also inefficient
We don’t have the land and water to provide the world with energy this way. Can we artificially improve the efficiency?
Radiant energy => chemical potential energy
CuInGaSe2
LEDs: semiconductors…. Like a diode, or a solar cell
• Forward Bias p-n junction: • Light is created by flowing current from
41% Efficiency achieved in laboratory Costs are estimated at $50,000/m2, so concentrators must be used.
Traditional Thin Film Solar Cells
CIGS (CuInGaSe2) World record: 19.5 % Stable Is there enough Indium left? amorphous Si World record: 12.1 % not completely stable CdTe World record: 16.5 % Stable Cd is toxic
A thin film of semiconductor is deposited by low cost methods. Less material is used. Cells can be flexible and integrated directly into roofing material.
Roll-to-Roll coating: A route to taking the costs below $50/m2
and keeping efficiency > 10 %.
P. Fairley, IEEE Spectrum. Jan. 2004 p.28
Nanosolar “A New Day Dawning? Silicon Valley Sunrise,” Nature 443, September 7, 2006, p. 19. Cheap, Fast, High Efficiency (~19%)
