SPIE Optoelectronic Integrated Circuits 2011 HelioVolt Presentation

1

Thin Film CIGS Photovoltaic Modules:Monolithic Integration and Advanced Packagingfor High Performance, High Reliability and Low Cost

Louay EldadaChief Technology Officer

© 2011 HelioVolt Corporation

January 27, 2011

http://spie.org/PW

Next Generation High-Performance and Low-Cost Solar Technology

• Disruptive CIGS PV technology: high efficiency low cost monolithic modules

• Extensive CIGS intellectual property portfolio

• 9+ years and ~$145MM of R&D

• Unique technology commercialization partnership with NREL

• Fully equipped production line and R&D line in Austin

• Team with deep technical expertise

• NREL-confirmed ~12% (11.8±0.6%) efficiency champion production module, with 10.8% average efficiency

• Efficiency roadmap to 16%+ in 2014

• Plan for production expansion under development

© 2011 HelioVolt Corporation 2

Competitive Technology Advantage• FASST® CIGS process advantages

– Two-stage process provides maximum flexibility to optimize precursor deposition method and composition of each layer: higher efficiency

– Most rapid synthesis of CIGS from precursors of any method: reduces capital costs

– Demonstrated state of the art crystalline quality: higher efficiency

– Unique, rapid, flexible optimization of CIGS surface quality: higher efficiency

• Advanced NREL liquid precursor technology

– Reduces capital costs and COGS

• Monolithic module circuit integration

– Reduces module assembly costs compared to discrete cell assembly

• Advanced module packaging

– Unique, high performance encapsulant, edge sealant, and potting compound supports product lifetime beyond standard 25 year warranty: reduces cost of electricity (¢/kWh)

Glass In

Module Out

GlassPreparation

FASST® CIGSProcess

ModuleFormation

Final Assembly& Test


CIGS: Highest Thin Film Efficiency

Source: Greentech Media, Prometheus Institute and Wall Street research.

2010 Module Efficiency Record Cell Efficiency

0% 5% 10% 15% 20% 25%

a-Si 1-j

a-Si/Micro

CdTe

CIGS

Multi-Crystalline Si

Mono-Crystalline Si


CIGS Contenders Approach

Company Process

Technology Substrate Cell or Module

Co-evaporation Glass Module

Co-evaporation Glass Tubular “Module”

Selenization Glass Module

Sputtering Steel Foil Cell

Nanoparticle

Sintering Metal Foil Cell

Electroplating Steel Foil Cell

HelioVolt FASST®

Currently Glass

Module


http://images.google.com/imgres?imgurl=http://www.masdarctf.com/images/Sulfurcell.gif&imgrefurl=http://www.masdarctf.com/portfolio.htm&usg=__JpORhlKvLhPWK8Fjn4rNIebDv0Y=&h=75&w=264&sz=12&hl=en&start=1&sig2=GLHjjy3ilfvckMIWrbNVTQ&um=1&tbnid=TiK620X7HG2sbM:&tbnh=32&tbnw=112&prev=/images?q=sulfurcell&hl=en&rls=com.microsoft:en-us&sa=N&um=1&ei=VBlbS6G6HsiXtgfB5oyYAg

http://www.honda.co.jp/soltec/index.html

Company CIGS Deposition

Uniformity COGS CapEx

Typical Module Efficiency

High High High 10-12%

Moderate High High 9%

Moderate Moderate High 10-12%

Low Moderate High 10%

Low Moderate Moderate 9%

Low Moderate Moderate 9%

High

Low

Low

10-12%

CIGS Contenders Results


Total: $0.27/Wp

HelioVolt Process

Glass In

GlassPreparation

FASST® CIGSProcess

ModuleFormation


Competitors’ CIGS Cell-Based Processes

Monolithic Integration is Key to Cost Leadership and Product Reliability

$0.06

Module Out

$0.07

$0.01

$0.13

Note: Input materials cost / Wp in cents.

SubstratePreparation

CIGSProcess

Contact & GridFormation

Cell Cut & Sort

$0.06

$0.15

$0.01

?

Cell Stringing


Total: $0.51+/Wp

$0.12

$0.17

Glass In

Module Out

Additional Costs

Stainless steel foil

Higher non-material inputs (e.g. labor)

Higher yield loss

Stringing material

Two encapsulant layers and outer frame

$0.08

?

?

$0.12

$0.04

Add’l: $0.24+/Wp


HelioVolt PV Module Production Line

Moly Deposition Exit Precursor Deposition Load FASST® Processor Load

FASST® Processor Unload Buffer Load

PVIC Lamination Junction Box Attach Final Eff. Test

Final PVIC Pattern Step


FASST® Reactive Transfer ProcessNon-Contact Transfer (NCT™) Synthesis

Source Plate

SubstrateCIGS Layer

Heat

Source Plate with Transfer Film

Pressure

Substrate

Cu, In,

Ga, Se

Process Step

• Independent deposition of distinct compound precursor layers on substrate and source plate

• Rapid non-contact reaction– Turns stack into CIGS with high efficiency structure– Combines benefits of sequential selenization with

Close-Spaced Vapor Transport (CSVT) for junction optimization

• CIGS adheres to the substrate and the source plate is reused

Rapid manufacturing process reduces capital amortization cost


CIGS Material Fundamentals

B.J. Stanbery, Critical Reviews in Solid State and Materials Sciences, 27(2):73-117 (2002)

T–X section of the phase diagram along the

Cu2Se-In2Se3 pseudobinary section of the

Cu–In–Se chemical system.

: CuInSe2 chalcopyrite phase

: In-rich/Cu-poor (Cu2In4Se7 & CuIn3Se5)

ordered defect compound (ODC) phase

CuInSe2 chalcopyrite crystal structure:

(a) conventional unit cell of height c, with a

square base of width a

(b) cation-centered first coordination shell

(c) anion-centered first coordination shell

showing bond lengths dCu–Se and dIn–Se.


Role of Micro and Nanostructuringin CIGS PV Device Operation

Observations on Device-Quality ( >15%) CIGS:

Large columnar grains

Copper deficiency compared to -CuInSe2

Compositions lie in the equilibrium 2-phase domain:domains, Cu-rich with p-type conductivity anddomains, Cu-poor with n-type conductivity,

form nanoscale p-n junction networks*;n-type networks act as preferential electron pathways,p-type networks act as preferential hole pathways,positive and negative charges travel to the contacts inphysically separated paths, reducing recombination

*Intra-Absorber Junction (IAJ) model, APL 87, 121904 (2005)


Composition Fluctuations and Carrier Transport in CIGS PV Absorbers

Experimental results* HAADF-TEM & Nanoscale EDS

– 5-10 nm characteristic domain size

– Chemical composition fluctuations found across the domains

p1: Cu:In:Ga:Se=31:14:7:48

p2: Cu:In:Ga:Se=27:15:9:49

p3: Cu:In:Ga:Se=30:15:6:49

– Dark domains are relatively Cu rich, bright domains are relatively Cu poor

*Applied Physics Letters, 87, 2005, 121904

HAADF-TEM: High-Angle Annular Dark-Field Transmission Electron Microscopy

EDS: Energy-Dispersive X-ray Spectroscopy


Reactive Transfer Processing Compound Precursor Deposition• Two methods have been developed for deposition of

compound precursors

• Low-temperature Co-evaporation

– Equipment requirements similar to conventional single-stage co-evaporation but lower temperatures lead to higher throughput and reduced thermal budget

• Liquid Metal-Organic molecular solutions

– Proprietary inks developed under NREL CRADA (Cooperative Research And Development Agreement)

– Decomposition of inks leads to formation of inorganic compound precursor films nearly indistinguishable from co-evaporated films (for some compounds)


Recrystallization of Nanoscale Vacuum Precursor Films Forming Large Grain CIGS

Precursor Film FASST® CIGS cross-section


HelioVolt-NREL CRADA Technology Advantages• Atmospheric (non-vacuum) processes

– Low capital equipment cost, 10-20x reduction vs. vacuum equipment

– Low thermal budget, low energy consumption

– Small footprint, 5-10x reduction vs. vacuum equipment

– High uptime

– High throughput

• Inks– Good compositional control by chemical synthesis

– A variety of materials can be synthesized; we have proprietary Cu-, In-and Ga-containing inks that densify to multinary selenide precursors

• Efficient use of materials– >95% material utilization vs. 80% for sputtering, 60% for evaporation


Printed Electronics Equipment & ProcessesLeveraged in PV

– Slow or static circuits

– Low integration density

– Large areas

– Rigid or flexible substrates

– Simple fabrication

– Low fabrication cost

– Fast switching circuits

– High integration density

– Small areas

– Rigid substrates

– Complex fabrication

– High fabrication cost

Complex Circuitry

High Cost

Simple Circuitry

Low Cost

Printed Electronics Conventional Electronics


Metal-Organic Decomposition (MOD) Precursor Film Deposition• Inorganic compound reaction CIGS synthesis provides

pathway for evolutionary adoption of MOD precursors

• Key drivers– Low capital equipment cost

– Low thermal budget

– High throughput

• Flexibility– Good compositional control by chemical synthesis

– Variety of Cu-, In- and Ga-containing inks can be synthesized and densified to form multinary sulfo-selenide precursors

• Efficient use of materials


Deposition of PV InksPreferred methods for printing CIGS precursor ink thin films

Ultrasonic Atomization Spraying

Slot Die Extrusion Coating


PVD vs. Ink Precursor Deposition

Cross Section Cross Section

PVD DepositedCIGS Precursor Film

Spray DepositedCIGS Precursor Film

Top View Top View


NREL CRADA – Hybrid CIGS by FASST®

SEM

• Exceptionally large grains• Columnar structure

XRD

• Chalcopyrite CIGS (& Mo)• (220/204) preferred orientation, helps

junction formation and improves solar cell performance

Hybrid CIGS efficiency reached parity with PVD-based CIGS


Device Quality CIGS in 30 Seconds:First Ultra-Fast Heating Results with Rapid Optical Processor (ROP)


SEMLarge, columnar grains

FASST® Yields High-Quality CIGS

QE curveGood carrier collection


Cd-Free Buffer for a Cd-Free Product

Uniform conformal Cd-free buffer on CIGS

CdS bufferCd-free buffer

Quantum Efficiency (QE) of CIGS with Cd-free buffer shows improvement over CdS, especially in the 400-500 nm wavelength range


Uniform High-Quality CIGS Polycrystalline Films Deliver 14% Cell Efficiency

Voc = 631 mV

Jsc = 31 mA/cm2

FF = 72%

Eff = 14%

Voltage (V)

Cu

rren

t D

en

sit

y (

A/c

m2)


Module Fab Process Flow

Glass In Module Out

= 2.5 hrs

PVIC

Sputtered Back Contact (Mo)

Cu-In-Ga-Se Precursor Films

CIGS by FASST Reactive Transfer

Buffer Layers

Sputtered Front Contact (TCO)

Bus Bars and Tabs

PVIC Test

Edge Sealant Application

Encapsulant Application

Pattern 1 (Laser Scribe)

Pattern 2 (Mech. Scribe)

Pattern 3 (Mech. Scribe)

Lamination

Final Test

Quality Control


Photovoltaic Integrated Circuit (PVIC)

CIGS Absorber

Substrate

Back Contact P1

BufferTCO Window

P2P3

–

– – – –

–

–

–

W.N. Shafarman et al., „Cu(InGa)Se2 Solar Cells‟ in Handbook of Photovoltaic Science and Engineering (2003)

Typical manufacturing steps of monolithic

interconnection for CIGS PV modules

Segment Isolation & Interconnection Scribesand Charge Transport

ScribeZone

CellLength

Cell

Wid

th

+ -

Bus Bar


Modeling for Device/Module Design

• HelioVolt CIGS device/module design further improved by various modeling methods, e.g. 2-D circuit design, device physics modeling, and thermodynamics modeling

Circuit model

Module

Sub-cell

Segment/Cell Sub-cell network

TCO network

Mo network

63.5

64

64.5

65

65.5

66

75

76

77

78

79

80

8 10 12 14 16 18 20 22

Mo

du

le F

F (%

)

Mo

du

le P

ow

er O

utp

ut

(W)

TCO Sheet Resistance (Ω/)

Power

FF (%)


Product Scaling and Performance Experience

Prototype Module30cmx30cm

Scalability Proof

Production Module1.2mx0.6m

Commercial Production Size

Cell0.66cm2

14%

3%

3 Months

5%

12%

2 Months

2%

8%12%

10 Months

Cell

Prototype

Module Progress

1364x scale-up

8x scale-up

Effi

cie

ncy

Effi

cie

ncy

Effi

cie

ncy

4 Months


FASST® CIGS Production Modules

Faceted CIGS crystals absorb light efficiently from all directions from dawn to dusk, giving HelioVolt CIGS its characteristic black color

Large grainswith no horizontal grain boundaries

support high efficiency

Cross-sectional

SEM view

Top view with SEM

120x60 cm2 Module


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icie

ncy

(%

)

G2 Modules – Feb 2010-present

Production Module Results in Last Year

G2 Modules – Feb ’10-present

EquipmentUpgraded

Average EfficiencyContinuously

Increasing

Effi

cie

ncy

(%

)


0%

10%

20%

30%

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100%

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120%

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MAY JUN JUL AUG SEP OCT NOV

Co

eff

icie

nt

of

Var

iati

on

(C

V)

Ave

rage

Eff

icie

ncy

2010

G2 Module Efficiency ProgressMax

Equipment

Capability Upgrade

and

Characterization

CV

Std Dev

AverageCV =

Efficiency: continuous improvement in efficiency average, maximum, and distribution


12% HelioVolt G2 Module Efficiency– NREL Measurement –

12% module independently verified by NREL (11.8±0.6%)


Best-In-Class Proprietary Packaging

• Edge Sealing: HVC has unique edge sealant solution that guarantees 25 year lifetime in high humidity environments

• Lamination: HVC has unique encapsulant sheet with high optical transparency, light trapping capability, good chemical compatibility with thin films, and outstanding ability to keep moisture out and withstand UV exposure

• Junction box: HVC has a J-box that is proven in the field; includes bypass diode to protect string from partial shading losses

• Front glass: HVC uses high-transparency low-iron tempered superstrate glass for highest optical performance and reliability


HelioVolt CIGS Module Product Spec

• Construction: Glass-glass laminate• Certification: IEC 61646, IEC 61730,

UL 1703, UL 790 Class A fire rating, CEC listing, CE mark in process

• Warranty: 25 years


Electrical Performance * HVC-170X

Maximum Power – Pmax 68.0 Watts

Open Circuit Voltage – Voc 74.5 Volts

Short Circuit Current – Isc 1.5 Amps

Operating Voltage – Vmp 55.0 Volts

Current at Operating Voltage – Imp 1.24 Amps

Maximum System Voltage – UL 600 Volts

Maximum System Voltage – IEC 1000 Volts*Standard Test Conditions (STC). Ratings are +/-10%.

HVC-170X

Physical & Mechanical Specifications HVC-170X

Length 1210 mm

Width 601 mm

Thickness 6.7 mm

Area 0.73 m2

Weight 12.3 kg

Positive Leadwire Length 660 mm

Negative Leadwire Length 660 mm

Connectors MC-4

Bypass Diode Yes

Cell Type CIGS

Frame None

Cover Type Tempered Glass

Encapsulation Edge Seal/Thermoplastic

Certification Testing

TestDescription

(per UL/IEC requirements)

Performance +/- 10% of specified electrical parameters

Outdoor Exposure 60 kWh/m2, maintain performance

Thermal Cycling • -40 to +90°C

Damp Heat • 85°C / 85%RH

Humidity Freeze • -40 to +90°C w/ condensation

Mechanical Robustness

• Shading hot spot • Connectors/J-box pull test• Mech loading: 400 lbs, 30 minutes• Impact: 2” 1.18 lb steel ball, 51” drop

Shock Hazard • No leakage current afterenvironmental exposure

UL: Underwriters Laboratories, IEC: International Electrotechnical Commission

UL 1703: Flat-Plate Photovoltaic Modules and PanelsIEC 61646: Thin-film Terrestrial Photovoltaic (PV) Modules

– Design Qualification and Type ApprovalIEC 61730: PV Module – Safety Qualification

Impact Testing

Temperature & RH Environmental Testing

Mechanical Load Testing


107.1%98.2%

0%

20%

40%

60%

80%

100%

120%

HF Exposure Only DH + HF Exposure

% o

f In

itia

l P

max

% of Initial Pmax, Light Soak StabilizedHF Test and DH+HF Test

99.9%89.9% 87.5%

0%

20%

40%

60%

80%

100%

120%

HelioVolt Competitor A Competitor B

% o

f In

itia

l P

max

Module Manufacturer

% of Initial Pmax, Light Soak StabilizedDH Test• Completed Damp Heat (DH) and

Humidity Freeze (HF) testing for pre-certification reliability screening

• DH Test:

– Followed IEC protocol 1000 hrs 85°C, 85% RH (Relative Humidity)

– Passed with virtually no degradation

• HF Test:

– All modules followed IEC protocol, which includes 50 cycles of thermal cycling (TC*) pre-conditioning, followed by 10 cycles of HF**

– Half of the modules had additionally gone through 1000 hrs of IEC DH test

– Passed with no degradation:No loss of Power, Voc, Isc

HF

Double torture not required in certificationtesting

DH

* TC cycle: -40°C to 85°C, 10min dwell at extremes** HF cycle: -40°C to 85°C/85%RH, 30min dwell at -40°C, 20hr dwell at 85°C/85%RH DH+HF

Completed Reliability Screening Tests


HelioVolt Module Rooftop Test Array

Factory Rooftop HelioVolt module test array. Array tracks performance of HelioVolt, as well as other thin-film and silicon modules, and inverters


HV Rooftop Test Facility STATUS

• Phase 1 installation complete

• ProSolar, Schletter, and CoolPly racking

• Xantrex, SMA, Fronius Inverters

• Competitor and HelioVolt modules

• 10kW initial capacity

• Thorough monitoring of energy harvest and weather conditions

CAPABILITIES

• Irradiance

– Plane of Array (POA)

– Global Total (GT)

• Weather

– Temperature

– Relative Humidity

• Electrical

– DC Voltage

– DC Current

– AC Voltage

– AC Current

– Inverter Efficiency


HelioVolt Modules(20° tilt, ballasted, Schletter racking)

• 32 HelioVolt modules in 4 strings on Schletter racking

• Full light soak effect achieved on first day

39© 2011 HelioVolt Corporation

Rooftop Performance –Comparison of All Arrays

• HelioVolt modules have highest yield, followed by Tier 1 mc-Si modules; CdTe & other CIGS lag behind

HelioVolt CIGSTier 1 mc-SiTier 1 CdTe2nd Glass Laminate CIGSTubular CIGS

One Day Comparison, All Arrays


• Development work based on HelioVolt patents and trade secrets will drive module efficiency from 10% to 16%

• Applied Research – HelioVolt’s partnership with NREL will drive module efficiency from 16% to 21%

6%

12%

18%

0%

2010 2011 2012 2013

Baseline Process

Active

Quenching,

Advanced

Composition

Grading Control

Ultrafast Heating,

Predictive Design

Advanced TCO,

Enhanced

Transmission,

Light Trapping

Roadmap to 16% Module Efficiency


Product Portfolio Built on Standard Component Platform

Commercial Rooftop Systems

BIPV – SpandrelsBIPV – Sunshades

Parking Structures

Utility Scale

• Front view

• 5‟x5‟ Element

• Framing provided by curtain wall manufacturer

• Standard or custom element

1‟X1‟300mm CIGS PVIC

2‟X4‟

5‟X5‟


Product Portfolio Evolution

2013 2014

Standard modules for commercial rooftops and utility applications.

Standard modules offered with system level solutions for commercial rooftops (including mounting, power management).New standard component introduced to reduce balance of systems costs.

Standard modules adapted for BIPV applications (facades, sunshades, roof tiles) including BIPV components with integrated power management.

11% 12% 14% 16%

2011 2012

Efficiency


Acknowledgments• Dr. Keith Emery and his team for the module efficiency

verification testingNational Renewable Energy Laboratory

• Prof. James Sites and his team for the help with cell characterizationColorado State University

• Dr. David S. Ginley and his team for the CRADA work on ink developmentNational Renewable Energy Laboratory

• The entire HelioVolt team for their role in the successful scale up of the CIGS reactive transfer technologyHelioVolt Corporation



Thank You!Louay Eldada

[email protected]

(512) 767-6060

© 2011 HelioVolt Corporation

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SPIE Optoelectronic Integrated Circuits 2011 HelioVolt Presentation