Solar Cells: when will they become economically feasible
-
Upload
jeffrey-funk-creating-new-industries -
Category
Business
-
view
105 -
download
1
description
Transcript of Solar Cells: when will they become economically feasible
![Page 1: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/1.jpg)
Solar Cells: When will they BecomeEconomically Feasible?
6th Session of MT5009
A/Prof Jeffrey FunkDivision of Engineering and Technology Management
National University of Singapore
For information on other technologies, see http://www.slideshare.net/Funk98/presentations
![Page 2: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/2.jpg)
Objectives
What are the important dimensions of performance for solar cells and their higher level systems?
What are the rates of improvement? What drives these rapid rates of
improvement? Will these improvements continue? What kinds of new systems will likely
emerge from the improvements in solar cells?
What does this tell us about the future?
![Page 3: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/3.jpg)
Session Technology
1 Objectives and overview of course
2 Two types of improvements: 1) Creating materials that better exploit physical phenomena; 2) Geometrical scaling
4 Semiconductors, ICs, electronic systems
5 MEMS and Bio-electronic ICs
6 Nanotechnology and DNA sequencing
7 Superconductivity and solar cells
8 Lighting and Displays
9 Human-computer interfaces (also roll-to roll printing)
10 Telecommunications and Internet
11 3D printing and energy storage
This is Part of the Seventh Session of MT5009
![Page 4: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/4.jpg)
Creating materials (and their associated processes) that better exploit physical phenomenon
Geometrical scaling◦ Increases in scale◦ Reductions in scale
Some technologies directly experience improvements while others indirectly experience them through improvements in “components”
As Noted in Previous Session, Two main mechanisms for improvements
A summary of these ideas can be found in 1) forthcoming paper in California Management Review, What
Drives Exponential Improvements?2) book from Stanford University Press, Technology Change and
the Rise of New Industries
![Page 5: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/5.jpg)
Creating materials (and their associated processes) that better exploit physical phenomenon◦ Create materials that better exploit phenomenon of
photovoltaic◦ Create processes that enable these materials to better exploit
phenomenon of photovoltaic Geometrical scaling
◦ Increases in scale: larger substrates and production equipment lead to lower cost in much the same way that cost of LCDs and other displays have fallen (see other sessions for more details)
Some technologies directly experience improvements while others indirectly experience them through improvements in “components” ◦ Better solar cells lead to better modules and new ways of
organizing electricity production
Both are Relevant to Solar Cells
![Page 6: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/6.jpg)
![Page 7: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/7.jpg)
http://www.economist.com/news/21566414-alternative-energy-will-no-longer-be-alternative-sunny-uplands
Solar cells are getting cheaper…………Partly because they are becoming more efficient
![Page 8: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/8.jpg)
Why does this slide make meoptimistic about solar?
![Page 9: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/9.jpg)
But a Long Way to Go
Coal-fired power plants $2.10 a watt Large hydroelectric systems can be cheaper
◦ Three Gorges Dam was supposedly about $1 a watt◦ But actual costs are widely believed to be much higher
Natural gas-fired peaking power plants -$6 a watt Large wind turbines -$2 a watt – but low capacity
utilization (27%) Solar panels currently selling for as low as US$0.70
a watt in large quantities◦ But installation costs are $2-4$ per watt◦ And capacity utilization is very low (18%)
Except for peaking plants (see next slide), we need much lower module and installation costs
http://en.wikipedia.org/wiki/Price_per_watt; http://thebreakthrough.org/index.php/programs/energy-and-climate/how-fast-are-the-costs-of-solar-really-coming-down/
![Page 10: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/10.jpg)
Electricity Usage by Time of Day in Florida
![Page 11: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/11.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 12: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/12.jpg)
Photovoltaic systemsSolar Cells in a Utility or on a Building
![Page 13: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/13.jpg)
Thermal Energy SystemsVery Different from Solar Thermal Systems
![Page 14: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/14.jpg)
Solar Cells Produce Electricity Based on Photovoltaic Effect
![Page 15: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/15.jpg)
1839: First recognized by the French physicist Alexandre-Edmond Becquerel
1883: First solar cell constructed from selenium by Charles Fritts
1946: modern junction semiconductor solar cell was first patented in 1946 by Russell Ohl
1954: first silicon solar cell was constructed by Calvin Fuller, Daryl Chapin, and Gerald Pearson
Subsequently other materials have been found some as recent as 10-15 years ago
Brief History of Photovoltaic Effect
![Page 16: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/16.jpg)
Semiconductor materials were found to exhibit the photovoltaic effect in the 1950s, 60s and 70s◦ Silicon, including single crystalline, polycrystalline, and
amorphous silicon◦ Cadmium Telluride (CdTe)◦ Copper indium gallium selenide (CIGS)◦ Gallium arsenide
But also non-semiconductor materials, which were more recently found◦ Photo-sensitive dyes (titanium oxide)◦ Some organic materials◦ Some of these materials can be used to make quantum dots or
have Perovskite crystals
Materials that Exhibit Photovoltaic Effect
![Page 17: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/17.jpg)
Incoming solar radiation creates “electron-hole” pairs in material These electrons and holes create electricity when they reach opposite
terminals of device Only photons whose energy exceeds band-gap of material create
electron-hole pairs◦ Other photons do not create electron-hole pairs
◦ Energy greater than this band gap is lost
There has been a search for materials that ◦ exhibit photovoltaic effect
◦ have appropriate band gap
◦ have little recombination of electrons and holes
◦ are inexpensive to acquire and process
Within a type of solar cell, there has been a search for the
appropriate combination of material and process specifications
Looking at Photovoltaic Effect in more Detail
Conductionband Band gap
Valenceband
![Page 18: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/18.jpg)
Materials with higher band gaps increase the amount of energy from each absorbed photon◦ but reduce the percentage of incoming radiation that
can be transformed into electrons and holes. Thus, there is a tradeoff between low and high
band gaps Given the distribution of the solar spectrum
◦ the optimal band gap in terms of efficiency can be calculated
◦ the maximum theoretical efficiencies can be calculated (about 30%)
◦ Many materials have a maximum theoretical efficiency of about 30%
What is the Best Band Gap?
![Page 19: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/19.jpg)
![Page 20: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/20.jpg)
Examples of Efficiency Losses
Reflection of photons by glass.Absorption of photons by glass (heat)
Recombination of electron hole pairs before reaching terminals(crystalline materials have less recombination)
Photons pass through material without generating electron-hole pairs
But even if the best band-gap is used, there will be losses
![Page 21: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/21.jpg)
One way to overcome limitations of individual materials is to use multiple junctions◦ Each has band gap that is appropriate for different part
of solar spectrum These solar cells can have
◦ much higher efficiencies than single junction ones◦ but they also have higher costs as multiple layers must
be deposited, patterned and etched One way to reduce costs is to
◦ focus sunlight onto multi-junction cells using concentrators
◦ but concentrating mirrors require mechanical and electronic controls, gears and other potentially unreliable components
Multiple Junctions
![Page 22: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/22.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 23: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/23.jpg)
Depends on a lot of factors but to simplify….
Cost of electricity depends on ◦ amount of incoming solar radiation◦ cost per “Peak Watt” of a module (based on a
predetermined amount of incoming solar radiation)
◦ cost of installation including cost of capital, land, labor, etc.: becomes more important as cost of “modules” drop
Cost per “Peak Watt” depends on ◦ cost per area of solar cells◦ efficiency of solar cells
Cost of Electricity
![Page 24: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/24.jpg)
Amount of incoming solar radiation
![Page 25: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/25.jpg)
world electricity demand
(18,000 TWh/y)
can be produced from
300 x 300 km²
=0.23% of all deserts
distributed over “10 000” sites
3000 km
Sources: Gerhard Knies, CSP 2008 Barcelonaand Vinod Khosla 25
deserts as solar farms
![Page 26: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/26.jpg)
Improvementsin what technology might make this economically feasible?
Source: WikipediaDesertec
![Page 27: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/27.jpg)
Source: Physica C: Superconductivity Volume 484, 15 January 2013, Pages 1–5. Proceedings of the 24th International Symposium on Superconductivity (ISS2011). CIGRÉ SC D1 WG38 Workshop on High Temperature Superconductors (HTS) for Utility Applications Beijing, China, 26 April 2013
Can these improvements make solar economical for Europe?
Now
2 years
4 years
![Page 28: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/28.jpg)
What About Cost Per Peak Watt of Modules?Depends on cost per area and Efficiency
Cost per area
($/m2) 50 100 200
Costper Area
200
100 50
0 2 4 6 8 10 12 14 16 18 20 22
Cos
t ($)
per
Pea
k W
att
1.5
1
.5
0
Efficiency
![Page 29: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/29.jpg)
Improvements in either Cost per area or Efficiency can lead to a Lower Cost per Peak Watt
Cost per area ($ per square meter)
50 100 200
Costper Area
200
100 50
0 2 4 6 8 10 12 14 16 18 20 22
Cos
t ($)
per
Pea
k W
att
1.5
1
.5
0
Efficiency
Improvements in Improvements in efficiency or cost per area
lead to lower costs per peak watt
![Page 30: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/30.jpg)
Real Cost Data is Complicated Rapidly falling costs and prices Sometimes faster than expected, other times
slower than expected Subsidies distort prices
◦ Not just subsidies for installations (U.S., Germany, Japan, Spain)
◦ But also alleged subsidies for producers (China) Alleged subsidies have led to
◦ Large exports of solar cells from China◦ Trade dispute◦ Smaller value added for solar cell producers both in
absolute and percentage terms
![Page 31: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/31.jpg)
http://www.economist.com/blogs/graphicdetail/2012/12/daily-chart-19
![Page 32: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/32.jpg)
Cost Data for Different Types of Solar Cell Materials
![Page 33: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/33.jpg)
http://cleantechnica.com/2013/01/22/chinese-solar-imports-drop-but-prices-continue-to-fall/
![Page 34: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/34.jpg)
Real Cost Data is Complicated (2)
Hard to separate long term and short term trends Likely that Chinese subsidies for Chinese
producers have caused short term fall in prices Thus prices may go up when subsidies are gone
◦ This may be why Suntech went bankrupt in March 2013 Rising use of natural gas in U.S. has also reduced
demand for solar panels and thus prices in the U.S.◦ Firms must reduce prices or have unused capacity, so
most firms will sell below costs Subsidies also make it hard to understand which
technology might be the cheapest in the future Sources: http://sync.democraticunderground.com/112739038; http://www.nytimes.com/2013/03/21/business/energy-environment/chinese-solar-companys-operating-unit-declares-bankruptcy.html?_r=0
![Page 35: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/35.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 36: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/36.jpg)
Maximum Theoretical Efficiency◦Similar for a wide range of materials ◦Black body limit
Best Laboratory Efficiencies◦Best efficiencies for cells produced in a
laboratory Best production efficiencies
◦Best efficiencies for cells (or modules) produced in a factory
Different Types of Efficiency
![Page 37: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/37.jpg)
Technology Production Facilities
Laboratories Theoretical Limits
Crystalline Silicon 18% 25% 29%
Micro-crystalline silicon 14% 20% 29%
Cadmium-Indium Gallium Selenide (CIGS)
11% 20% 29%
Cadmium Telluride (CdTe) 11% 17% (20.4%) 29%
Amorphous Silicon 8% 13% 20%
Organic Cells 2% 8% (11.1%) 31%
Dye-Sensitized Cells 12% 31%
Best Solar Cell Efficiencies and Theoretical limits(for single materials in 2010)
Sources: U.S. DOE, 2010; Wang Qing and Palani Balaya (personal communication)
![Page 38: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/38.jpg)
Crystalline materials have lower recombination of holes and electrons◦ Also high efficiencies for other crystalline materials
(e.g., GaAs) More research on silicon
◦ Longer history of silicon research than other materials◦ Silicon’s current dominance (cheaper equipment and
demand-based subsidies) reinforces this perspective Do the other materials have more potential for
improvements? And if so, how much?
Why Does Crystalline Silicon have the Highest Efficiencies?
![Page 39: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/39.jpg)
![Page 40: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/40.jpg)
Perovskite
DyeSensitizedCZTSSe
Organic
QD
![Page 41: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/41.jpg)
Rapid Improvements
Quantum dots (discussed in Session 5)
Organic materials Perovskite cells
![Page 42: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/42.jpg)
Increases in best laboratory efficiencies of organic and dye-sensitized solar cells
http://www.asiabiomass.jp/english/topics/1208_05.html
![Page 43: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/43.jpg)
http://electronicdesign.com/article/components/organic-solar-cell-architecture-taps-next-performance-plateau
Increases in best laboratory efficiencies of organic solar cells
![Page 44: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/44.jpg)
Improvements in Organic Cells
Many types of organic materials, but they all contain carbon◦ Many substitutions are
tried One substitution is
fullerenes Placing them in the
right place is important Synchrotron is used to
analyze the energy levels and thus the right places to place the fullerenes
![Page 45: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/45.jpg)
Worldwide OPV production forecast
Source: Solar&Energy, Recent Organic Solar Cell Technology and Market Forecast (2010 - 2015
![Page 46: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/46.jpg)
2000 2005 2010 2015
16
14
12
10
8
6
4
2
Rapid Improvements in Efficiency of Perovskite Solar Cells
Perovskite
Organic
Dye Sensitized
Amorphous Silicon
Perovskite-based solar cells, Hodes G, science 342, 317 (2013, Oct): 317-318
![Page 47: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/47.jpg)
Improvements in Efficiency (1) Perovskite cells are a hybrid of organic and
inorganic materials and they have a certain type of crystal structure◦ Thus may use materials classified as other types of
solar cells◦ Key difference is in crystalline structure
Efficiencies similar to crystalline silicon are possible due to its single crystalline structure
First two cells in 2009 and 2010 were liquid junction cells that were not stable
Perovskite-based solar cells, Hodes G, science 342, 317 (2013, Oct): 317-318;http://www.technologyreview.com/news/521491/a-new-solar-material-shows-its-potential/
![Page 48: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/48.jpg)
Improvements in Efficiency (2) Recent ones have high diffusion lengths and
long lifetimes for holes and electrons (i.e., low recombination)
Researchers have shown that it is relatively easy to modify the material so that it efficiently converts different wavelengths of light into electricity
May be possible to form a solar cell with different layers, each designed for a specific part of the solar spectrum (i.e., multi-junction cell)
Perovskite-based solar cells, Hodes G, science 342, 317 (2013, Oct): 317-318;http://www.technologyreview.com/news/521491/a-new-solar-material-shows-its-potential/
![Page 49: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/49.jpg)
Very low cost of Perovskite (and Organic) Low-temperature deposition methods
◦ typically solution-based spin coating as compared to sputtering or vapor deposition
One-fifth the cost of current silicon-based solar cells on an area basis, due to the simpler manufacturing process
No rare materials or toxic (lead is worst material) If lifetime related problems are solved and if lab
efficiencies reach 20%, costs of $0.20 per peak Watt are expected
Perovskite-based solar cells, Hodes G, science 342, 317 (2013, Oct): 317-318;http://www.solarika.org/blog/-/blogs/new-hope-for-cheaper-solar-cells-using-perovskites
![Page 50: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/50.jpg)
http://www.youtube.com/watch?v=oQ2bz6jlbz0
![Page 51: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/51.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 52: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/52.jpg)
One way to overcome limitations of individual materials◦ Each has band gap that is appropriate for different part
of solar spectrum These solar cells can have
◦ much higher efficiencies than single junction ones◦ but they also have higher costs as multiple layers must
be deposited, patterned and etched One way to reduce costs is to
◦ focus sunlight onto multi-junction cells using concentrators to reduce amount of photovoltaic material
◦ but concentrating mirrors require mechanical and electronic controls, gears and other potentially unreliable components and they can only be currently used in cloudless skies
Multiple Junctions
![Page 53: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/53.jpg)
Two-Junction Solar Cells
![Page 54: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/54.jpg)
![Page 55: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/55.jpg)
Ideally as you increase the number of band gaps the efficiency increases
![Page 56: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/56.jpg)
![Page 57: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/57.jpg)
Multiple Junctions Add Cost
For the highest efficiency solar cells, $50,000 per square meter
High costs come from maintaining crystalline structure even with 20 layers
Grown as one large crystal
![Page 58: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/58.jpg)
Organic materials can be roll printed or sprayed on top of each other
Organic tandem cells have the same efficiencies as do single-junction organic cells
But this may change
But some incur less additional cost than others
![Page 59: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/59.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 60: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/60.jpg)
Type of material◦ Availability in earth’s crust, Processing requirements
Number of layers◦ More layers means more processing steps
Temperature of processing◦ Higher temperatures means higher costs (e.g.,
semiconducting materials, crystalline silicon)◦ http://www.youtube.com/watch?v=F2KcZGwntgg (from 1:50)
◦ Organic materials can be roll printed
Thickness of materials◦ More difficult to reduce thickness of epitaxial formed silicon
(crystalline silicon) than thin-film deposited materials (CIGS, CdTe, amorphous silicon)
Scale of substrates and production equipment◦ Same as with LCDs and semiconductor wafers
What Determines Cost per Area?
![Page 61: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/61.jpg)
Fewer layers Less materials Lower temperature and simpler processes
◦ Organic materials, CIGS, and Perovskite can be roll printed onto a substrate
Perhaps lower scale right now so greater potential for increases in scale◦ Many forms of thin film already use large scale production
equipment
◦ But large scale equipment has not been implemented for some technologies, particularly roll printing
◦ Roll printing is applicable to some processes and many processes for organic solar cells
Thin Film Has Potentially Lower Costs
![Page 62: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/62.jpg)
Roll Printing of Organic Solar Cells
![Page 63: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/63.jpg)
Roll printing of organic solar cells
Notice the simplicity
Also notice the small size of the solar cells – still a long way from reaching its optimum scale
Discussed more in two weeks
Organic solar cells, roll-to roll printing16 May 2013http://reneweconomy.com.au/2013/on-a-roll-csiro-printing-australias-largest-solar-cells-58992
![Page 64: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/64.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 65: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/65.jpg)
http://www.economist.com/node/21543215 Source: Television Making: Cracking Up, Economist, January 21st, 2012, p. 66
Most cost reductions of LCD panels came from larger scale substrates and equipment. Similar effect for Solar
![Page 66: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/66.jpg)
Increases in Scale of LCD Substrates (and also IC Wafers, Solar Substrates) Equipment costs per area of output fall as size
of equipment is increased, similar to chemical plants
For chemical plants◦ Cost is function of surface area (or radius squared)◦ Output is function of volume (radius cubed)◦ Thus, costs increase by 2/3 for each doubling of
equipment capacity For LCD Substrates, IC Wafers, and Solar
Substrates◦ Processing, transfer, and setup time (inverse of
output) fall as area of substrate increases since entire area can be processed, transferred, and setup together
![Page 67: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/67.jpg)
Another Benefit from Large Panels is Smaller Edge Effects
Panel
Equipment
Effect Effects: the equipment must be much wider than panel to achieve uniformity
Ratio of equipment to panel width falls as the size of the panel is increased
![Page 68: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/68.jpg)
Increases in LCD Substrate Size
Source: www.lcd-tv-reviews.com/pages/fabricating_tft_lcd.php
![Page 69: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/69.jpg)
![Page 70: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/70.jpg)
Scale of photolithographic aligners (upper left), sputtering equipment (top right), and mirrors for aligners (lower left) for LCD equipment
Source: http://www.canon.com/technology/canon_tech/explanation/fpd.html
![Page 71: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/71.jpg)
http://www.electroiq.com/articles/sst/print/volume-50/issue-2/features/cover-article/scaling-and-complexity-drive-lcd-yield-strategies.html
![Page 72: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/72.jpg)
![Page 73: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/73.jpg)
![Page 74: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/74.jpg)
Solar cells also benefit from increases in scale of production equipment
Crystalline silicon solar cells are made in wafers, just like semiconductor chips◦ Their costs fall as wafers and production equipment
are made larger, but improvements are difficult Thin-film solar is made on substrates, like
LCDs◦ Their costs fall as substrates and production
equipment are made larger CIGS and organic solar cells can be roll printed
◦ Materials can be deposited and patterned using roll-to roll printing
◦ Consider Self-Aligned Imprint Lithography (SAIL)
Increases in Scale and Solar Cells
![Page 75: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/75.jpg)
$0.0 $0.5 $1.0 $1.5 $2.0 $2.5 $3.0
Web preparation
Sputter Gate 1 Metal
Align and Expose
SiN, a-Si, N+ dep
Align and Expose
Si RIE & Resist Strip
Ultrasonic Clean
Align and Expose
Sputter Dep/ ITO
Align and Expose
Sputter Dep Interconnect
Align and Expose
Web cost
SAIL solves alignment problem & saves money
$0.0 $0.5 $1.0 $1.5 $2.0 $2.5
Condition web (de-hydro)Gate metal deposition (Al)
PECVD oxide/nitride/Si/N+ depositionSD metal deposition (Cr)
Imprint SAIL structureWet etch Cr
RIE etch n+&Si&SINRIE etch oxide
Plasma etch Al
Thin down 2P (clear gate-pad)Pre-Cr-etch CleaningRIE etch n+&Si&SIN
Thin down 2P (clear gate-pad)Wet etch CrRIE etch n+
Under-cut Al (1-3 um)RIE etch oxide
Strip-off 2PWeb cost
cost
per
ft2
$0.00
$2.00
$4.00
$6.00
$8.00
$10.00
$12.00
$14.00
$16.00
$18.00
Photolithography SAIL
Cost of Patterning
Backplane materials costs for R2R photolithography & SAIL
R2R SAIL
R2R photolith (AGI)
Multiple photoresist applications
dominate photolithography process materials costs
![Page 76: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/76.jpg)
2 3 4 5 6 7 8 9 1010
-3
10-2
10-1
100
eq
uip
me
nt
co
st
[M$
] /
th
rou
gh
pu
t [c
m2 /
S]
generation
equipment cost scaling comparison: panel stepper vs R2R imprinter
100 mm R2R imprinter 330 mm R2R imprinter
R2R Imprinters are much cheaper than Panel Stepper used in Photolithography
(and benefits from increases in scale)
Source: Roll-to-Roll Manufacturing of Flexible Displays, Hewlett Packard, Phicott
![Page 77: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/77.jpg)
1 2 3 4 5 6 7 8 9 1010
-2
10-1
100 e
quip
men
t cos
t [M
$] /
thro
ughp
ut [c
m2 /
S]
generation
equipment cost scaling comparison: panel CVD vs R2R CVD
330 mm R2R PECVD
1 m R2R PECVD
Source: Roll-to-Roll Manufacturing of Flexible Displays, Hewlett Packard, Phicott
PECVD (plasma enhanced chemical vapor deposition) is also cheaper when doing R2R Printing
(and benefits from increases in scale)
![Page 78: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/78.jpg)
Installation costs are now more than the module costs on a per Watt basis
Lower on a per Watt basis with◦large-scale than small-scale systems◦High-efficiency than low-efficiency
modules Lower on a per-area basis with thin-film or rolled materials than with thick materials (crystalline silicon)◦Just unroll a roll of organic solar cells
What about Installation Costs?
![Page 79: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/79.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 80: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/80.jpg)
Can further decrease costs It is easier to reduce thickness of thin-film
materials than crystalline silicon◦ their thickness depends on deposition of materials◦ thickness of crystalline silicon materials depends on
cutting silicon ingots into wafers But it can also lead to lower efficiencies
◦ Less active material increases the chances that photons will pass through the material before they create an electron-hole pair
What if we can increase the amount of time that a photon spends within the material for a given thickness?◦ Thus enabling reductions in thickness
Reductions in Thickness
![Page 81: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/81.jpg)
Rationale: Light trapping increases the optical thickness of a silicon cell by 10--‐50 times
Hence, theoretically it is possible to achieve similar efficiencies with a thinner layer material
![Page 82: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/82.jpg)
How do solar cells work? Improvements in cost of electricity from solar cells
Improvements in Efficiency Multi-junction cells
Improvements in cost per area Increases in scale Reductions in thicknesses
Conclusions
Outline
![Page 83: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/83.jpg)
Conclusions (1) Cost of electricity from solar cells is dropping rapidly Silicon is most widely used material
◦ Will further cost reductions for silicon occur?
◦ Or have we reached the limits?
Large number of materials and processes suggests that many improvements can still be achieved◦ Rapid increases in efficiency are still occurring for some
materials: organic, quantum dot, perovskite, multi-junction solar cells
◦ Scale up of substrates and equipment have not been done for some materials
![Page 84: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/84.jpg)
Conclusions (2) Other improvements are also occurring
◦ Reducing thickness of materials
Installation costs are becoming larger as a percentage of total costs◦ How can they be reduced?
◦ With roll printed solar cells, or with higher efficiency solar cells?
![Page 85: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/85.jpg)
Appendix
![Page 86: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/86.jpg)
![Page 87: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/87.jpg)
![Page 88: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/88.jpg)
![Page 89: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/89.jpg)
© Scholtes 2004 2 September 2004 Page 89
U.S. Dept of Energy Oil price forecast
Source: U.S. Department of Energy, 1998
120
100
80
60
40
20
01975 1980 1985 1990 1995 2000 2005
Year
1982
Trend predicted 1981
1984
1985
1986 1987
1991
1995
ActualDo
llars
pe
r B
arr
el
1983
![Page 91: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/91.jpg)
![Page 92: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/92.jpg)
BanBest Laboratory and Maximum Theoretical Efficiencies vs. Band-Gap of Material
![Page 93: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/93.jpg)
2009 2010 2011 2012 2013 2014 20150.5
1
1.5
2
Micro (Poly) Crystalline Silicon
Cost (USD) per Peak Watt of Solar Cells
Cadmium Indium Gallium Selenide (CIGS – thin film)
Source: Lux Research (2011)
Thin Film Silicon
Cadmium Telluride (thin film)
USD
![Page 94: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/94.jpg)
http://thinkprogress.org/climate/2011/12/11/387108/solar-power-much-cheaper-than-most-realize-study/?mobile=nc
![Page 95: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/95.jpg)
http://thinkprogress.org/climate/2011/12/11/387108/wp-content/uploads/2011/06/Screen-shot-2011-06-08-at-3.20.01-PM.png
![Page 96: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/96.jpg)
http://cleantechnica.com/2012/03/14/ultra-thin-solar-cell-company-unstealths-aims-to-cut-cost-of-solar-cells-in-half-images/
![Page 97: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/97.jpg)
http://revolution-green.com/2013/07/17/solar-at-30-cents-per-watt/ http://blogs.berkeley.edu/2013/06/18/the-california-solar-initiative-is-ending-what-has
-it-left-behind/ http://www.resilience.org/stories/2013-08-16/it-keeps-getting-cheaper-to-install-solar-
panels-in-the-u-s http://energyathaas.wordpress.com/2013/06/17/the-california-solar-initiative-is-endin
g-what-has-it-left-behind/ http://thinkprogress.org/climate/2011/12/11/387108/solar-power-much-cheaper-than-
most-realize-study/
![Page 98: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/98.jpg)
I Disagree with Conventional Wisdom Implications of learning curve (cost of producing
product falls as cumulative production increases) Although learning curves don’t exclude non-factory
activities, linking cost reductions with production ◦ focuses policy, other analyses on production of final product◦ implies that research done outside of factory is either
unimportant or being driven by production of final product◦ for solar, has encouraged demand-based policies that
subsidize installation of solar cells ($130B just in Germany) as opposed to more R&D, which has encouraged focus on existing technologies
We should first understand direct drivers of cost reduction, then develop good policy
![Page 99: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/99.jpg)
http://electronicdesign.com/article/components/organic-solar-cell-architecture-taps-next-performance-plateau
Increases in best laboratory efficiencies of organic solar cells
![Page 100: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/100.jpg)
Increases in best laboratory efficiencies of organic and dye-sensitized solar cells
http://www.asiabiomass.jp/english/topics/1208_05.html
![Page 101: Solar Cells: when will they become economically feasible](https://reader034.fdocuments.in/reader034/viewer/2022051613/54c85f114a7959d7758b484c/html5/thumbnails/101.jpg)
Worldwide OPV production forecast
Source: Solar&Energy, Recent Organic Solar Cell Technology and Market Forecast (2010 - 2015