Solar Energy Technologies: Research, Applications and
OpportunitiesPresentation to DOE/National Association of State Universities and Land Grant Colleges (NASULGC)
August 3, 2004
John P. Benner, Division ManagerElectronic Materials and Devices
Solar Technology Programs
• Photovoltaics (PV)
• Concentrated Solar Power (CSP)
• Solar Thermal
• Solar Lighting
Solar Lighting
Distributed Distributed sunlightsunlight
Electric lightElectric light
Fiber used in 2003 design
Fiber used in 2004 design
Estimated Itemized Cost in Small (~500 units) Quantities
Primary/secondary mirror - $200.00Balance of roof-mounted system - $1,000.00Light Distribution - $1,200.00Hybrid Luminaires/Controls - $600.00Building Preparation - $500.00Installation/Alignment/Calibration - $500.00Total - ~$4,000.00 per m2 of collection area
Estimated Levelized Cost 0.12 $/kWh
Each 3 mm fiber carries 350 lumens
Thin-walled polymer vessel of water
Glazing(s)
Supply/Return Piping
Immersed heat exchanger
Insulation
Unpressurized, Integral Collector Storage (UPICS) Schematic
Low-Cost Solar Water Heaters
Low-Cost Solar Water Heaters
Technical Challenges:• Polymer durability – the key technical challenge• System performance
– Overheating protection– Heat exchanger sizing and placement
• Building code issues– Use of plastics, e.g., flammability– Structural concerns, e.g., roof weight, wind loading
• Manufacturing process design– Thermoforming and rotomolding tolerances and temperature limits
Status:Status:Mild climates: $0.08 - $0.10/kWh in 2003Cold climates: $0.12 - $0.14/kWh in 2003
Concentrating Solar Power
Parabolic Trough
Power Tower
Dish/Stirling
Concentrating Photovoltaics
SW Solar Energy PotentialSolar Land
Capacity AreaState (MW) (Sq Mi)
AZ 3,267,456 25,527CA 821,888 6,421NV 743,296 5,807NM 3,025,920 23,640
Total 7,858,560 61,395
The table and map represent land that has no primary use today, exclude land with slope > 1%, and do not count sensitive lands.
Solar Energy Resource ≥ 7.0 kWhr/m2/day (includes only excellent and premium resource)
Current total generation in the four states is over 100,000 MW.
Planned additions in four states over the next 3 – 5 years are 37,099 MW of which 87.6% is natural gas.
1000 MW of CSP requires 7.7 mi2.
Kramer Junction SEGS Collector Availability
95.0
95.5
96.0
96.5
97.0
97.5
98.0
98.5
99.0
99.5
100.0
1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Avai
labi
lity
- %
Concentrating Solar Parabolic Trough Systems
• Current Advances– 20% improvement in
receiver efficiency– Development of lower-cost
concentrator designsReduction in LEC from $.16/kWh to $.10/kWh
• Projected Advances– Integration w/ low-cost
thermal storage– Improved efficiency through
advanced receivers and high temperature operation
– Cost reductions through plant scale-upReduction in LEC from $.10/kWh to $.04-$.06/kWh
UVAC / Cermet Comparision - SEGS VI
0%
20%
40%
60%
80%
100%
120%
5:00 7:00 9:00 11:00 13:00 15:00 17:00 19:00
Ther
mal
Effi
cien
cy -
%
0
200
400
600
800
1000
1200
Inso
latio
n - W
/m^2
UVAC Loop (3/4) Base Loop (5/6) Insolation 3/28/01
Parabolic TroughDevelopment Activities
• Trough R&D
– Low-cost concentrator designs
– Near- and long-term thermal storage
– Advanced receiver designs
– Alternative power cycles
• In 2001 Congress asked DOE to determine what would be required to deploy 1000 MW of Concentrating Solar Power in the Southwest U. S.
• DOE and CSP industry approached the Western Governors’ Association through the Western Interstate Energy Board to explore implementation.
• A number of Southwestern States have high solar potential and some have renewable energy portfolio standards (particularly, AZ, CA, NM, and NV) and the potential to gain from development of their solar energy resources.
• Western Governors’ likely to create Southwest Solar Task Force to investigate mechanisms for implementing regional initiative
1000 MW Initiative
World PV Cell/Module Production (MW)World PV Cell/Module Production (MW)
1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 20010
100
200
300
400
Rest of worldEuropeJapanU.S.
33.6 40.2 46.5 55.4 57.9 60.1 69.4 77.6
88.6125.8
154.9201.3
287.7
390.5
2002
500
Source: PV News, March 2004
600 561.8
700
800744.1
2003
PV Manufacturing R&D Cost/CapacityPV Manufacturing R&D Cost/Capacity
Actual Projected
PV Manufacturing Research Data (DOE/U.S. Industry Partnership)PV Manufacturing Research Data (DOE/U.S. Industry Partnership)
Reduction in Module Price vs Cumulative Shipments1980 thru 1999 History(total world)
1
10
100
10 100 1000 10000Cumulative Worldwide Shipments MWp
$[19
99]/W
p
25% reduction in price forevery doubling of cumulative shipments
Source: Paul Maycock
Reduction in Module Price versus Cumulative ShipmentsExperience Curve
PV Market Sectors
Consumer CommunicationOff Grid Hybrid/CommercialGrid Connected BIPV Utility Scale
2000 Actual 0.3 GW 2010 Projected 4.5 GW
• Key companies: Shell Solar, BP Solar, GE, Sharp, Kyocera, Sanyo, Motech, Cypress-SunPower• ~85% of today's market• ~800 MW capacity (to double in near-term)• Proven products, 20-25 year warranties• Large ingots: 100 kg CZ, 250 kg casting• Multiple ingot growth with melt replenishment• Wire saw: < 250 µm wafers, < 200 µm kerf
Crystalline Silicon (Ingot-Based) PV
• Efficiency Status Cells ModulesFloat-zone 24.7 22.7*Czochralski 22.0 13–17Cast poly 19.8 10–16
• Batch/continuous processing• High-efficiency devices in production• Well-developed technology base--new understanding of defects/impurities * Best prototype
02679603
Wire saw
Dislocation Map Grain Boundary Map
4000 5000 6000 7000 80003000
Reflectance MapLight Induced Current Map
• Efficiency Status Cells ModulesEFG 14–16 11–13String ribbon 14–16 10–12Thick Si/substrate 16.6 9–10Thin Si/substrate 5-12* ~ 7**
*Depends on process (some efficiencies not verified)** Best prototype
• Key companies: RWE Schott Solar, Evergreen Solar, GE, Pacific Solar, Kaneka• Status varies from prototype modules to pilot
production to commercial products (many MW)• Proven products (~ 6% of market)• Capacity increases underway—many tens of MW in near term• Improved performance from defect/impurity and passivation studies• Increasing interest in thin silicon growth 02679605
RWE Schott
GESilicon Source
P = 1 atm.
SubstrateTc
SiI2Th
Si
SiI4
I
Si3 µm/min~20 µm[110]
Crystalline Silicon (Non-Ingot-Based) PV
Ink Jet Printing of Ag and Cu contacts for Si Solar Cells 8% Cells on Si3N4
a
b
Line thickness: 15 µmLine width: 250µmDep. temperature : 180 oCAnn. temperature: 850 oCSubstrates from Evergreen Solar
Building Higher Efficiency onto the Expanding Infrastructure for Silicon PV
Heterojunction a-Si/c-Si cellPotential >20% Efficient
p-type crystal-Si wafer
a-Si intrinsic thin layer
ITO
a-Si n-type emitter
Al-Si alloyed p+-type back-surface field
Al
p-type crystal-Si wafer
a-Si intrinsic thin layer
ITO
a-Si n-type emitter
Al-Si alloyed p+-type back-surface field
Al
14.17 %Best Voc=628 mV (p-type CZ cell record)
GaNP on Si TandemPotential >30% Efficient
GaN0.02P0.98
GaP GaN0.03P0.97
SiSi
Si
Conventional PV Installations
Powerlight Roof Integrated PV System
Combines PV Power with Energy Saving from Insulation
United Solar Shingles
Advances in PV System Design Can Also Achieve
Cost Advantages
Efficiency status: Cell 12-19Submodule 10-12Module 7–11 Commercial 5–10
• Understanding of film growth, microstructures, defects, and device physics
• Reproducible high-efficiency processes• Multiple junctions
Thin-Film PV
Key companies: United Solar/ ECD, Shell Solar, EPV, Global Solar/ITN, First Solar, Iowa Thin Films, HelioVolt, Wurth Solar, Showa-Shell, DayStar, Miasolé• Multi-MW/year in consumer products• 5 and 10 MW plants operational; few tens of MW in near term• Unique products for building integration 02679607
CIGS Performance Across the Entire Compositional Range for Tandem Cells
18
16
1412
10
Effic
ienc
y (%
)
1.61.51.41.31.21.11.0Absorber band gap (eV)
0.9
0.8
0.7
0.6
0.5
Ope
n C
ircui
t vol
tage
(V
1.61.51.41.31.21.11.0Absorber band gap (eV)
14.5%
19.3%
14.5%
10.2%
Polycrystalline Thin Film Tandem Solar Cell
7059 Cornning glass
CTO
ZTO
S-CdS:O
CdTe
CuxTe back-contact
ITO
Ni/Al grids
In contact
c-ZTO / i-ZnO
CBD-CdS
CIS
Mo
Soda-lime glass
Ni/Al grids
In contact
CdTe top cellAchieved 50%transmission,12.7% efficiency
CIS bottom cellAchieved 14.5% efficiency
FY06 milestone: 15% efficient 4-terminal device will be met one year early
Combinatorial, Focused-Beam X-ray Diffraction
Ga2O3
In2O3
SnO2CdO
ZnO
Developing Capabilities for Combinatorial Materials Science at NREL
Accomplishments: High Throughput Methods
TCO Combi at
NREL
4000
3500
3000
2500
2000
1500
1000
500
0
Con
duct
ivity
(Ω
cm
)-1
1009080706050403020100%In for Zn (as-measured by EPMA)
35
30
25
20
15
10
5
0
Mobility (cm
2/V*s)
80
70
60
50
40
30
20
10
0
Carrier C
oncentration x 1019 (#/cm
3)
conductivity mobility carrier concentration
100
1000
807060504030202θ (deg.)
Library 2%In: 15 → 50
15.4 20.0
25.6
49.3
33.4 42.9
2
4
68
100
2
4
68
1000
2
807060504030202Θ (deg.)
34.041.9
49.458.8
67.875.3
Library 3%In 34->75%
2
4
68
100
2
4
68
1000
2
807060504030202Θ (deg.)
94.592.0
86.3
62.771.1
78.9
Library 4%In: 62 -> 95
Research Time
Compressed to one week
High Throughput Research Methods
Efficiencies: Si (up to 400X) 27GaAs (up to 1000X) 28GaInP2/GaAs (1X) 30.3GaInP2/GaAs (180X) 30.2GaInP2/GaAs/Ge (40–600X) 36.9
• Module efficiencies: 15-17% (Si); best prototypes: >20% (Si), >24% (GaAs), 28% (GaInP2/GaAs/Ge,10X)
• Large space markets drive GaInP2/GaAs and GaInP2/GaAs/Ge commercial cell production
High-Efficiency and Concentrator PV
Key companies: Amonix, Spectrolab, Emcore, Sunpower, ENTECH; Solar Systems ltd• Manufacturability demonstrated
– Low-concentration, line focus– High-concentration, point focus– High efficiency cells (Si, GaAs,
multijunctions) in production• Limited applications in today's markets
– Hydrogen generation may be wellmatched
02679613
ENTECH
AmonixSpectrolab
7
8.08.0
6.55.7
0
1
2
3
4
5
6
7
8
9
Fixed Horizontal(1000 W/m2
Rating)
Fixed Latitude Tilt(1000 W/m2
Rating)
1-Axis Tracker(1000 W/m2
Rating)
Concentrator (850 W/m2 Rating)
100.0% 113.4% 139.5% 139.4%
Solar Tracking Provides Solar Tracking Provides Energy BenefitsEnergy Benefits
Tracking systems provide 15 to 20% more energy than fixed PVTracking systems provide 15 to 20% more energy than fixed PV
Up to 40% more than fixed horizontal systemsUp to 40% more than fixed horizontal systems
Novel Concepts, Excitonic Devices and New Materials
• Dye-sensitized TiO2 photochemical cells• Potential for very low cost• Nanocrystalline TiO2, with monolayer dye sensitizer,in liquid electrolyte• 11%-efficient cell; scale-up for consumer products underway• Dye stability issue• Gel or solid-state electrolytes in research• Photoelectrochromic window (with WO3)
02679615
• Key Companies: GE, Kodak, Konarka, NanoSolar, NanoSys, Luna, UltraDots …
Organic Solar CellsNanostructured Oxides – Polymer Composites
Accomplishments: Discovery
Controlled Nucleation Layers for Nanocomposite Organic Solar Cells
2D Structure Fiber
NanofibrilLayer
Substrate
ControlledNucleation Layer
The Goal
ZnO Nanofibrils
Wetted with P3HT
Best ResearchBest Research--Cell EfficienciesCell EfficienciesEf
ficien
cy (%
)
Universityof Maine
Boeing
Boeing
Boeing
BoeingARCO
NREL
Boeing
Euro-CIS
200019951990198519801975
NREL/Spectrolab
NRELNREL
JapanEnergy
Spire
No. CarolinaState University
Multijunction ConcentratorsThree-junction (2-terminal, monolithic)Two-junction (2-terminal, monolithic)
Crystalline Si CellsSingle crystalMulticrystallineThin Si
Thin Film TechnologiesCu(In,Ga)Se2CdTeAmorphous Si:H (stabilized)
Emerging PVDye cellsOrganic cells(various technologies)
Varian
RCA
Solarex
UNSW
UNSW
ARCO
UNSWUNSW
UNSWSpire Stanford
Westing-house
UNSWGeorgia TechGeorgia Tech Sharp
AstroPower
NREL
AstroPower
Spectrolab
NREL
Masushita
Monosolar Kodak
Kodak
AMETEK
Photon Energy
UniversitySo. Florida
NREL
NREL
NRELCu(In,Ga)Se2
14x concentration
NREL
United Solar
United Solar
RCA
RCARCA
RCA RCARCA
Spectrolab
Solarex12
8
4
0
16
20
24
28
32
36
University ofLausanne
University ofLausanne
Siemens
2005
Kodak UCSBCambridge
Groningen
University LinzBerkeley
Princeton
UniversityLinz
Solar Technologies Research and Applications
• Solar technologies maintain an aggressive learning curve and are cost competitive as alternative energy sources in a growing number of markets– Approaching retail electricity rates in Japan and Europe
• Low retail energy costs in the U.S. discourage manufacturing and deployment of new technologies
• Projected technology improvements can bring solar electricity generating costs to U.S. retail electric levels
Natural Gas Shortage Natural Gas Shortage Transmission and Distribution Transmission and Distribution LimitationsLimitationsCEOCEO’’s Call for National Energy s Call for National Energy StrategyStrategy
With BalanceWith BalanceInternational Pressure on Global International Pressure on Global Climate ChangeClimate ChangeState and Local Initiatives for State and Local Initiatives for Renewable EnergyRenewable Energy
Changing Energy Landscape
From: Nathan Lewis, Global Energy Perspective
Energy Reserves and Resources
020000400006000080000
100000120000140000160000180000
(Exa)J
OilRsv
OilRes
GasRsv
GasRes
CoalRsv
CoalRes
UnconvConv
Reserves/(1998 Consumption/yr) Resource Base/(1998 Consumption/yr)
Oil 40 -78 51 -151
Gas 68 -176 207 -590
Coal 224 2160
Rsv=ReservesRes=Resources
From: Nathan Lewis, Global Energy Perspective
Mean Global Energy Consumption, 1998
4.52
2.7 2.96
0.286
1.21
0.2860.828
00.5
11.5
22.5
33.5
44.5
5
TW
Oil Coal Biomass NuclearGas Hydro Renew
Total: 12.8 TW U.S.: 3.3 TW (99 Quads)
• Nuclear (fission and fusion)• 10 TW = 10,000 new 1 GW reactors• i.e., a new reactor every other day for the next 50 years
2.3 million tonnes proven reserves; 1 TW-hr requires 22 tonnes of UHence at 10 TW provides 1 year of energyTerrestrial resource base provides 10 years of energyWould need to mine U from seawater (700 x terrestrial resource base)
• Carbon sequestration
• Renewables
Sources of Carbon-Free Power
From: Nathan Lewis, Global Energy Perspective
From: Paul B. Weisz, Physics Today, July 2004
Solar Land Area Requirements
3 TW
From: Nathan Lewis, Global Energy Perspective
From: Paul B. Weisz, Physics Today, July 2004
H2 Purification, Storage,
Dispensing
H2 Production
Fuel Cell
StationaryGeneration
Fuel Processor
or Electrolyzer
Fuel Cell
H2
Reformate H2 /
The Need to Produce Fuel“Power Park Concept”
Fuel Production
Distribution
Storage
From: Nathan Lewis, Global Energy Perspective
Energy Costs
02
4
6
8
10
12
14
$/GJ
Coal Oil Biomass ElectB
razi
l Euro
pe
$0.05/kW-hr
www.undp.org/seed/eap/activities/wea
Million M2 per Year
$/M2
10
100
10000
1000
1
1 10 100 1000 10000
Glass
Coated Glass
Paint
Large-Area Optical and Electronic Materials
Low Cost Processes
FPD
PV
SolarFuels
Electrode
Fuel Cell Bipolar plate
Solar Technology Opportunities
• Source of Carbon Free Power
• Solar energy is the only currently practical primary source in sufficient abundance to sustain growing energy demand for centuries to come.
• Massive change to energy infrastructure requires decades to implement, along with massive investment.