Latest Developments in Solar
Technology&Own Research Results
Eicke R. Weber
with Andrei Istratov, Tonio Buonassi, Mathias Heuer, Matthew
Pickett
Department of Materials Science and Engineering
University of California, Berkeley, CA 94720
and
Materials Science Division, Lawrence Berkeley National Lab
California-German Solar Day, San Francisco November 7, 2005
Making the case for renewable energies:
2004: 380ppm CO2!
http://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htm
2004: 380 ppm, beyond the range of the last 500kys !
When will the temperature follow [CO2] ?
How high will it go?
When will we leave the region of stability??
Time before present [kys]
Photovoltaics Industry Basics
• Exceeds $1 billion in
1999.
• Growing at a rate of
20-30%/year over the
past decade.
• Big players on the
market, making
serious long-term
investment: BP, Shell,
Sharp, Kyocera, Qcells, Mitsubishi, GE,
Sanyo, Hitachi,
Schott…….
Source: Trends in Photovoltaic Applications - Survey report of selected IEA countries between 1992 and 2003. International Energy
Agency (IEA) Photovoltaic Power Systems Programme (PVPS). Report # IEA-PVPS T1-13:2004
Development of the Global PV Market
300 MWp / a
Thin film (a-Si)
Mono
-Si
Multi-Si
2000
Renewable Energy Law, D
100 000 Roofs Program, D
Ribbon-Si
Residential Roof Program,
JPN
1990
1980
Graph courtesy G. Willecke, 2004
1000 Roofs Program,
D
Annual PV Module Shipments
containing crystalline Si
2003: 700 MWp
2004: 1.1 GWp, exceeding even the
optimistic growth curve!
MWp/a 4,800
4,400
4,000
40 % CAGR
25% Growth
3,600
3,200
2,800
2,400
2,000
1,600
Annual
Module
Shipment
(Crystalline
Silicon)
15% Growth
1,200
800
400
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Source: 2000-2003 Strategies Unlimited
Actual Shipments
Projection (2003)
Learning Curve of PV Modules
(crystalline silicon)
100
1980
[€/Wp]
1990
2000
10
2010
2020
1
10-4
10-3
10-2
10-1
1
10
102
103
Cumulative installed PV Peak Power [GWp]
At todays price PV electricity costs about $0.25/kwh,
to be compared with $0.32/kwhr PG&E charges for TOU customers
during peak time (noon-6pm)
Silicon Feedstock Problem
• Silicon is used to make
over 90% of today’s
solar cells.
• Although silicon is the
second-most abundant
element on the Earth’s
surface, it must be
refined and purified
before being used in a
solar cell.
• Currently, the demand
for purified silicon
feedstock exceeds
supply, causing silicon
feedstock prices to soar.
Conclusions so far:
• Rapid development of renewable energies can delay the
climate change caused by greenhouse gas emissions
• PV is a virtually unlimited source of renewable energy,
other techniques can make an important contribution
• Crystalline Si photovoltaics is the only presently available
PV technology for the required growth rates
• Developing technologies to use ‘dirty silicon’ will help to
enable further aggressive growth of crystalline Si PV
Research issues:
multicrystalline silicon for solar cells
Problem: Multicrystalline silicon materials contains
high density of impurities (most importantly, transition metals)
which reduce the solar cell efficiency. The cheaper is the silicon
feedstock, the higher is the concentration of the impurities.
Approach: Investigate the nature of efficiency-limiting
defects in solar cells and develop technologies for reduction
of their impact on solar cells.
Funding for UC Berkeley research is provided by National Renewable Energy Laboratory
The suite of synchrotron radiation based
x-ray microscopy tools enables us to:
•
•
ALS at LBNL
APS at ANL
ALS Beamline 10.3.2:
µ-XRF: Map spatial distribution of metal precipitates
Determine elemental composition of each precipitate
µ-XAS: Determine chemical state of metals in the precipitates
XBIC: Characterize their recombination activity
Two types of metal clusters in mc-Si
T.Buonassisi et al., J.Appl.Phys. 97, 63503 (2005) and J.Appl.Phys. 97, 74901 (2005).
Large (up to 25 µm) inclusions
Often found within grains.
Found in low density.
Fe is dominant, often with presence of other
slowly diffusing metals (e.g., Cr, Mo, Ti).
Fe is oxidized and is very similar to Fe2O3
Small (10’s of nm) nanoprecipitates
Typically accumulated along grain
boundaries.
Found in high density.
No slowly diffusing metals detected.
Consist of Fe, Cu, or Ni in a silicide form.
The concept of metal defect engineering in solar cells
T.Buonassisi, A.A.Istratov, M.A.Marcus, B.Lai, Z.Cai, S.M.Heald, E.R.Weber, Nature Materials, 4, 676 (2005)
Interstitial
Substitutional
Metals,
complexes
Metal Silicide
Nanoprecipitates
Inclusions
(Foreign
Particles)
Generally, a high density of interstitial metals or metal-silicide nanoprecipitates
affects the minority carrier diffusion length stronger than a low density
of large metal precipitates/inclusions
Example: dissolution of metal clusters during processing
Interstitial
Substitutional
Metals,
complexes
Metal Silicide
Nanoprecipitates
Inclusions
(Foreign
Particles)
• High-temperature treatments dissolve metal silicide nanoprecipitates, creating a
higher density of smaller defect clusters.
• Rapid cooling freezes defects in place, ensuring a high spatial density of
recombination centers. Poor performance results.
Goal of defect engineering of metal impirities:
improvement through change in the state/distribution of metals
Interstitial
Substitutional
Metals,
complexes
Metal Silicide
Nanoprecipitates
Inclusions
Gettering improves material by removing metals from the device area
Defect engineering improves material by converting metals into their least
recombination active state, while keeping the metals in the device area
Properly chosen annealing sequence decreases spatial density of metal
clusters and improves the minority carrier diffusion length
T.Buonassisi, A.A.Istratov, M.A.Marcus, B.Lai, Z.Cai, S.M.Heald, E.R.Weber,
Nature Materials, Aug. 14, 2005
Quenched:
LD = 7-8 µm
Quenched&Re-annealed:
LD = 18-20 µm
Slow-cooled:
LD = 7-8 µm
Mc-Si intentionally contaminated at 1200oC, either quenched in silicone oil, or quenched and
then reannealed again at 655oC, or slowly cooled in the furnace.
The processing used for this experiment was not optimized.
Defect engineering of metal impurities in solar cells:
Can improve solar cell performance without removing the metals
Has the potential to extend the range of “useable” material
to dirtier “solar-grade” silicon without additional expensive
processing or purification steps.
Extensive fundamental knowledge is necessary to design
treatments which accomplish the goals of defect engineering.
We do have the tools to accumulate such knowledge!
Silicon Solar Consortium
SILICON SOLAR CONSORTIUM
‰ A new Industrial/University Cooperative Research Center
for the Silicon Photovoltaic Community similar to the
existing SiWEDS I/UCRC (see www.siweds.org)
- NSF may enable organizational structure via I/UCRC support $$
- We have already established a process for providing Industrial
deliverables via non-competitive joint research
‰ “Non- Competitive” Task Areas, e.g.:
- Defect Engineering, Impurities, Gettering
- Cast, Ribbon, Sheet, Thin Film Material
- Surfaces, Devices, Simulation
- Metrology
Silicon Solar Consortium
Interested Members
•
•
•
•
•
BP Solar
GE Energy
Evergreen Solar
Applied Materials
PV companies in Europe & Asia
*********************
• UC-Berkeley, NCSU, Ga.Tech., U Konstanz, …..
Further info: please contact me at: weber@berkeley.edu
Silicon Wafer Engineering and Defect Science Center
Established 1997
http://www. siweds.org
Industry / Gov. Members
Academic Community
CentroTherm (Germany)
Dong-bu Electronics (Korea)
Hynix (Korea)
Intel Corp.
Komatsu Silicon
Lawrence Semiconductor
LG Siltron Inc. (Korea)
MEMC Electronic Materials
Samsung Electronics Co.
SEMATECH
SRC
Texas Instruments
Toshiba Ceramics
Siltronic (Germany)
Arizona State U
Schroder
Brandenburg TU
Kraemer
(Cottbus, Germany)
Hanyang U (Korea) JG Park
M I T:
Kimerling
N C State U
Rozgonyi
Stanford
Pianetta
U of Washington
Dunham
U C Berkeley
Weber
U T Dallas
Kim
Waseda U (Japan)
Homma
A National Science Foundation
Industry/University
Cooperative Research Center
(NSF I/U CRC)
MISSION
FUNDING
$640k – Members (2004)
$415k – NSF (2003-08)
$1M/5years – Enhancement Projects
The Center offers a unique multi-university, multicompany culture which addresses critical silicon
materials wafer issues for advanced integrated
circuit and photovoltaic manufacturing. The
education of graduate and post-graduate students
in silicon materials engineering and defect science
is a critical component of the Center’s activities.
Director: George Rozgonyi
North Carolina State University
RESEARCH AREAS
Bulk Defects
Surface Defects
Metrology
Modeling/Simulation
Layered Structures: Si/SiGe/SOI
Photovoltaic clusters in eastern Germany:
Opportunities for Investments
German Solar Day
San Francisco
November 7, 2005
The German photovoltaic market will continue to grow fast
with an expected growth rate of 30% p.a.
Recent announcements:
Germany’s installed Photovoltaic power
„
[in MWp]
1000
“In perhaps the most noteworthy
display of the effectiveness of
Germany's feed-in solar energy
rebates, the construction of the
world's largest solar photovoltaic
power plant has been finished: a 10
MW facility in Bavaria, Germany.”
PV installations p.a.
(market volume)
800
Expected
growth rate:
30% p.a.
cumulative installed
PV power
600
Germany's Incentives Propel World's
Largest Solar Project
PowerLight, January 2005
400
„
200
0
1998
1999
2000
2001
2002
2003
2004
2005e
Plans for a PV system with an 18 MW
capacity are taking shape
“The project is led by Berlin-based
Solon AG. Each month, about 1.5 MW
of capacity will be installed near the
town of Arnstein…by June 2005 it will
become by far the world's largest PV
installation”
PHOTON International, February 2004
MWp: Mega Watt peak (Performance in standard test conditions)
Source: Photon Magazine, UVS, BSI 02/2005
© 2005 | IIC
The photovoltaic clusters in eastern Germany offer most
concentrated know-how and excellent partnering opportunities
Value
chain
Silicon
Silicon
Wafers
Wafers
Company
1
2
3
4
5
Cells
Cells
6
7
8
9
Modules
Modules
10
11
12
Wacker
WackerSiltronic
Siltronic
Freiberg
Freiberg
Deutsche
DeutscheSolar
SolarAG
AG
PV
PVCrystalox
CrystaloxSolar
SolarAG
AG
Freiberg
Freiberg
Erfurt
Erfurt
220
220MWp
MWp
30
30MWp
MWp
1)
700
7001)
160
160
ASi
ASiIndustries
IndustriesGmbH
GmbH
EverQ
GmbH
EverQ GmbH
Arnstadt
Arnstadt
Thalheim
Thalheim
30
30MWp
MWp
30
MWp
30 MWp
--2)2)
50
50
Q-CellsAG
Q-CellsAG
Deutsche
DeutscheCell
CellGmbH
GmbH
Thalheim
Thalheim
Freiberg
Freiberg
350
350MWp
MWp
60
60MWp
MWp
700
700
--1)1)
60
60MWp
MWp
30
MWp
30 MWp
2)
230
2302)
60
60
Ersol
ErsolSolar
SolarEnergy
EnergyAG
AG Erfurt
Erfurt
Sunways
Arnstadt
Sunways
Arnstadt
Solarwatt
SolarwattAG
AG
Solon
AG
Solon AG
SMD
SMDaleo
aleoSolar
Solar
Solar
Factory
Solar FactoryGmbH
GmbH
Dresden
100
Dresden
100MWp
MWp
Berlin,
Greifswald
90
MWp
Berlin, Greifswald 90 MWp
Prenzlau
90
Prenzlau
90MWp
MWp
320
320
300
300
200
200
--1)1)
GSS
GSSSolar
Solar
Heckert
HeckertSolar
Solar
Erfurt
Erfurt
Gera
Gera
15
15MWp
MWp
15
MWp
15 MWp
Chemnitz
Chemnitz
15
15MWp
MWp
Antec
AntecSolar
Solar
CSG
Solar
CSG SolarAG
AG
Arnstadt
Arnstadt
Thalheim
Thalheim
20
20MWp
MWp
10
MWp
10 MWp
40
40
20
20
21
Sulfurcell
Sulfurcell
Solarion
Solarion
Berlin
Berlin
Leipzig
Leipzig
10
10MWp
MWp
pilot
pilot
20
20
20
20
22
Odersun
OdersunAG
AG
Frankfurt
Frankfurt(Oder)
(Oder)
pilot
pilot
20
20
15
16
17
18
19
20
Solara
SolaraWismar
WismarGmbH
GmbH
ASS
Solar
ASS Solar
Clusters in eastern Germany
600
600
60
60MWp
MWp
25
25MWp
MWp
14
© 2005 | IIC
Capacity target
Current
2005/2006
# employees
Freiberg
Freiberg
Wismar
Wismar
13
Thin
ThinFilm
Film
Location
90
90
20
20
20
20
20
20
11
14
Rostock
12
Berlin
11
20
22
Magdeburg
19 6
5
Leipzig
Erfurt
18 8 3
15 4 9
16
21
7 13
17 1
2
Dresden
10
Freiberg
1) Total of Solarworld AG 2) Total of Ersol
group
The IIC acts as an one-stop agency for international
investors in eastern Germany, covering the entire
investment decision process
Investment Decision Process
Strategy &
Market Analysis
ƒ European
strategy
discussions
ƒ International
location
benchmarking
ƒ Market
research
© 2005 | IIC
Market Entry
ƒ Site selection
ƒ Merger &
Acquisitions and
Joint Venture
support
Project Financing &
Implementation
ƒ Financial and
incentives consulting
ƒ Identification of
suitable
real estate
ƒ Negotiation support
Eastern Germany offers some of the most attractive
incentive packages in the European Union for investments in
the region
Cash
Incentives
Investme
nt
incentive
s
Reduced
Interest
Loans
State
Guarantees
Labor grants
Operating
incentive
s
Training
Assistance
R&D Support
Cash Incentives
• Grants for investments in production facilities
– up to 50%* of the investment for small and medium-sized companies (SME**)
– up to 35%* of the investment for larger companies
• Communities investments in site infrastructure covered with up to 90% of the
costs
Reduced interest loans & state-guarantees
• Available if investor contributes a reasonable stake of equity (typically 15%***)
• favorable interest rates, linked to German government debt levels
• Guarantees up to 80% of total loans
Labor grants
• Grants covering a portion of new employees’ first year salaries if previously
unemployed
Training assistance
• Pre-employment training for up to three months, including hiring fees. No
obligation to hire the trainees afterwards
• Qualification costs for employees up to 50% in SME**
R&D Support
• Wide variety of financing possibilities focused on reducing labor and equipment
costs on specific projects for small and medium-sized companies
Note: * depends on the region and investment size, incentive level for investments > €50 mil. is reduced
** Small or medium-sized enterprises have up to 249 employees and up to €50 mil. sales or up to 249 employees and a balance sheet total up to €40 mil. Enterprises with more
than a 25%
equity stake in the investing company will be consolidated.
*** Total amount of equity and subsidy-free loans has to be at least 25%.
© 2005 | IIC