HelioVolt Confidential and Proprietary
Thin-Film Photovoltaics
Bert Haskell – Director of Product Development
HelioVolt Confidential and Proprietary
Outline
• Overview of HelioVolt
• Thin Film CIGS technology
• Thin Film device structure and packaging
• Distributed energy in urban environments
• Rooftop PV
• Building Integrated PV
HelioVolt Confidential and Proprietary
About HelioVoltFounded: 2001Location: Austin, TXEmployees: 100+Technology: Revolutionary method for manufacturing high-efficiency
CIGS PV circuits
o Completed $101M Private Equity Financing Round late 2007o Launching 20 MW commercial production facility in Austino Seeking strategic partners for product collaboration
HelioVolt Confidential and Proprietary
MissionTo develop and commercialize a new generation of efficient, safe,
reliable, and attractive thin-film photovoltaic solar power
products that are the first to enable energy production at cost
parity with conventional sources of electricity.
Cost
Durability
Efficiency
Lowest cost thin film circuits, less than half that of
silicon PV and one fourth that of current Building
Integrated PV (“BIPV”) products
Warranted Lifetime of 25 years for first products
Comparable conversion efficiencies to multicrystalline
silicon
HelioVolt Confidential and Proprietary
Solar Product Availability• Crystalline Silicon ~ 18% conversion efficiency
• Multi-crystalline Silicon ~ 14%
• Amorphous Silicon ~ 6-8%– Flexible and rigid
• Cadmium Telluride ~ 9-10%– First Solar capturing significant market share for
central power applications
• CIS/CIGS ~10-12%– New commercial availability entering the market in
2008
90% of
current market
10% of
current market
but fastest
growing segment
HelioVolt Confidential and Proprietary
Inefficiencies in Today’s Value Chain
15 – 20 + % margins at each step in the value chain
$0.00
$1.00
$2.00
$3.00
$4.00
$5.00
$6.00
$7.00
$8.00
Raw silicon Wafer mfg Cell Module assembly
Inverters System Eng Installation
$
$
$
$
$
$
2nd Generation
Thin Film
Advantage
System
Integration
Advantage
US PV System
Price $/w ~ $7.50
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Thin Film Manufacturing Challenges
HelioVolt’s technology addresses most significant PV challenges:
CIGS thin-film technology is the most promising candidate to replace
expensive silicon-based technologies
FASST™ process technology will produce high quality CIGS
photovoltaics in minutes, an 80-98% reduction over other CIGS thin-
film manufacturing processes
$1.00
$0.03
x-Si CIGS
Semiconductor Materials Cost ($/Wp) Time (minutes)
3
30
360
Metal Selenization Coevaporation HelioVolt FASST™
360
HelioVolt Confidential and Proprietary
CIGS Thin-Film Products
substrate
Moly
CIS
ZnO buffer P2
P1
P3
Alloy of Copper, Indium, Gallium and Selenium
CIGS is one of three known intrinsically stable PV materials (with Silicon and Gallium Arsenide)
• Intrinsic stability required for building integrated products
More efficient absorber of light than any other known semiconductor
Requires 1/100th of the material compared to silicon for comparable light absorption
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
PVIC Manufacturing Process Flow
Glass CleanMetal
Deposition
Metal
Pattern (P1)
Precursor
DepositionFASST™
Synthesis
Buffer
Deposition
Absorber
Pattern (P2)TCO
DepositionTCO
Pattern (P3)
Product
Packaging Test & Ship
1.
Front End
2. CIGS
Synthesis
3.
Buffer
4. Device
Processing
5.
Back End
PVICs
HelioVolt Confidential and Proprietary
Proprietary FASST™Manufacturing Process
FASST™ - Field Assisted Simultaneous Synthesis and Transfer
HelioVolt’s two step process enables
high throughput low cost manufacturing of CIGS PVICs.
Precursors
Substrate
Stage 1:Precursor Deposition
Stage 2:Rapid Thermal
Anneal and Separation
Heat
Electrostatic &
Mechanical
Pressure
Precursors
Substrate
CIGS Layer
Printing Plate
Printing Plate
HelioVolt Confidential and Proprietary
Initial Standard Module Product Specifications• HelioVolt CIGS Photovoltaic Module
– Residential or commercial applications
– BIPV products in development
• Nominal Power at STS = 75 – 85 W
• Voltage at Max Power = 67v
• Connectors: Tyco Micro Solar Lock
• Approximate physical dimensions:
– 620 mm x 1200 mm x 7 mm (unframed)
– Glass-glass laminate construction
– Approximate weight - 12 kg
• Certifications (at launch): UL (ULC) , IEC
• Warranty: 25 years
HelioVolt Confidential and Proprietary
Planned
Efficiencies 11% 12% 13% 14%
Conversion
Product Roadmap
2009 2010 2011 2012
Rigid modules for commercial
and residential applications
AC modules for traditional
applications
Modules adapted for BIPV
applications:
Facades, sunshades, roof tiles
AC BIPV components
Flexible substrate product
development
HelioVolt Confidential and Proprietary
Advantages of thin film PV• Efficient and high performing materials
– Direct bandgap semiconductors– Better energy output – kWh/KW – CIGS record at 19%+ conversion efficiency
• Significantly reduced costs– Less material usage
• Not affected by silicon supply shortages
– Potential for improving costs throughout value chain
• Advanced manufacturing techniques– Fewer processing steps– Monolithic integration of circuits– Automation
• Better aesthetics
HelioVolt Confidential and Proprietary
Device structure and design
• Thin Film PV Devices
– Equivalent Circuit
– Key Electrical Parameters
– Cell Structure
– Isolation and Interconnect
• Thin Film Cell Design
– Module requirements
– Cell Optimization
HelioVolt Confidential and Proprietary
Key Electrical Parameters
• Standard Test Conditions (STC): 1,000 W/m² , 1.5 AM, 25ºC
• Inverter should adjust load to achieve Pmax
I-V curve for a solar cell
efficiency
fill-factor
Source: Wikipedia
HelioVolt Confidential and Proprietary
Cell Structure(typical CIGS solar cell cross section)
• Source: Handbook of Photovoltaic Science and Engineering, Luque & Hegedus, Wiley 2003.
Soda lime glass (3mm – substrate)
Mo (0.5µm – back contact)
Cu(InGa)Se2 (2 µm – absorber-layer p-type)
CdS (0.05µm – buffer layer n-type)
ZnO (0.5µm – doped conductive front contact)
High Resistance ZnO
-
+
TCO layer(Transparent Conductive Oxide)
CIGS layer
HelioVolt Confidential and Proprietary
Isolation and Interconnect(typical CIGS solar cell)
Soda lime glass
Mo
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo P1
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo
Cu(InGa)Se2
CdS
High Resistance ZnO
P1
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo
Cu(InGa)Se2
CdS
High Resistance ZnO
P1
P2
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo
Cu(InGa)Se2
CdS
ZnO
High Resistance ZnO
P1
P2
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo
Cu(InGa)Se2
CdS
ZnO
High Resistance ZnO
P1
P2 P3
HelioVolt Confidential and Proprietary
Isolation and Interconnect (typical CIGS solar cell)
Soda lime glass
Mo
Cu(InGa)Se2
CdS
ZnO
High Resistance ZnO
-
+ P1
P2 P3
-
+
HelioVolt Confidential and Proprietary
Thin Film Cell Design
Drivers
Module Constraints
Cell Optimization
Module
Scribe zone
Cell length
Cell width
+ -
Bus Bar
HelioVolt Confidential and Proprietary
Module requirementsVoltage
Vmodule = Vcell x Ncell
Application dependent
24 V for battery charging
String inverters limited to 600V or 1000V strings
PVAC requires higher voltages (~250V) for optimum efficiency
CurrentImodule = Icell
Power Output/ EfficiencyEfficiency = Power output/{Module Area * Solar
Incident}
Maximize to achieve best $/watt
HelioVolt Confidential and Proprietary
Cell Optimization
1. Determine acceptable module voltage range
2. Select cell length that maximizes module efficiency within the acceptable module voltage range
Trade-off between dead area from scribing and I²R losses through TCO. (Shorter cells have less resistive loss, but more dead area from scribing)
TCO properties are critical (resistance vs. transmissivity)
Vcell is a characteristic of the material bandgap
Icell depends on the cell area
Cell length (mm)
η%
3 4 5 6 7
Curve not based on actual data; Illustrative purposes only
HelioVolt Confidential and Proprietary
Device Packaging and Reliability• Packaging
– Bus bars
– Encapsulation
– Junction box
– Framing
• Reliability
– Common Failure Modes
– Stress Testing
– Certification Testing
– Certification Failure Modes
HelioVolt Confidential and Proprietary
Bus bars
Bus bar is required to avoid resistive losses associated with current collection
Tinned copper ribbon is typical bus bar material
Bus bar requires sacrificial cells on each end of module
Bus bar must conduct power outside of encapsulated module and into junction box.
+ -
Bus Bar
HelioVolt Confidential and Proprietary
Encapsulation
Glass-glass construction is typical for thin film modules
Encapsulant (EVA, PVB,..) adheres cover glass and keeps out moisture
Encapsulant must be very transparent and must not degrade with environmental/UV exposure
Top glass
Bottom glassEncapsulant sheet
Laminate
Solar module lamination system
HelioVolt Confidential and Proprietary
Junction box
J-Box typically integrated with connectors for creating module strings
Must capture and seal bus bar exit zone
Often integrates bypass diode to protect string from partial shading losses
HelioVolt Confidential and Proprietary
Framing
Thin-film modules are available in framed and un-framed configurations
Framing is usually extruded aluminum and must be grounded
Residential modules must be framed (UL); Commercial/PPA (inaccessible to public) can be unframed
Framing can provide additional edge seal protection.
Framed Un-framed
HelioVolt Confidential and Proprietary
Stress Testing
1. Temperature
2. Voltage
3. Current
4. Moisture
5. Thermal cycling
6. UV-Vis
7. Mechanical
-40ºC to +90ºC - 6 hour cycle –
200 cycles(per UL/IEC test requirements) 85ºC / 85% RH – 1000
hours(per UL/IEC test requirements)
HelioVolt Confidential and Proprietary
Certification Testing Test Name Test Description (Per UL/IEC
test requirements)
Performance +/- 10% of specified electrical parameters
Outdoor Exposure 60kWh/m^2 , Maintainperformance,Maintain leakage
Thermal Cycling • -40C to +90C (UL)
Damp Heat Humidity Freeze
•85/85• -40C to +90C w/condensation
Mechanical Robustness
•Shading hot-spot •Connectors /J-boxes pull test•400 pound weight loading•Steel ball impact (51 inch, 1.18lb)
Shock Hazard •No leakage current after environmental exposure.
HelioVolt Confidential and Proprietary
Growth of Distributed Energy
Office building
and school
roof top
examples
(MW) 2009E 2010E 2011E 2012E
Global Rooftop PV
Demand 4,437 6,860 9,506 13,061
Commercial Rooftop Systems Building Integrated Photovoltaic Systems
Residential
roof tile and
façade
examples
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
PV Solutions for Urban Solar Applications
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Commercial flat roof (attached & ballasted)
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Pitched roof (tiles & rack mount)
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Covered areas (walkways, outdoor Cafés, etc..)
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Curtain Wall (Spandrel or renovative façade)
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
B
O
S
Balance of Systems(Mounting, wiring, inverters, etc.)
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
B
O
S
PV Solutions for Urban Solar Applications
HelioVolt Confidential and Proprietary
PV Mounting Systems for Commercial Rooftop
• Flat Roof
– Attached
– Ballasted
– Hybrid
– BIPV
• Standing Seam Metal Pitched Roof
– Attached
– BIPV
• Tile/Shingle Pitched Roof – Attached
– BIPV
HelioVolt Confidential and Proprietary
Flat Roof – Attached• Description
– Typically very low slope (1/4 :12)
– Built-up Roof (BUR) or Membrane construction
– Attaches to building framing
• Benefits/Issues – Requires roof penetration
– Reduced dead load to roof structure
– Engineered live loading of structure
– Less constrained tilt angles due to higher tolerable wind loads
– Improved drainage management
• Module Requirements– Compatible clamping hardware
– Potential weight limitations
• Leading Hardware Vendors– Schletter (world leader)
– Unirac
– DPW solar
– ProSolar
– RoofScreen
Schletter - attached system
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Flat Roof – Ballasted• Description
– Typically very low slope (1/4 :12)
– Built-up Roof (BUR) or Membrane construction
– Relies on dead weight to maintain position on roof
• Benefits/Issues – Requires no roof penetration
– Less involvement from building roofer
– Less impact on roof warranty
– Limited pitch options due to wind loads
– Applied to roofs where weight is not a big concern
• Module Requirements– Compatible clamping hardware
– Good off-angle harvest
• Leading Hardware Vendors– Schletter (world leader)
– Unirac
– DPW solar
– SunLink
– Schuco
DPW - ballasted system
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Flat Roof – Hybrid• Description
– Typically very low slope (1/4 :12)
– Built-up Roof (BUR) or Membrane construction
– Relies on weight plus minimal frame attachment
• Benefits/Issues – Requires some roof penetration
– More pitch options than ballasted
– Can be used to reduce ballast in weight constrained situations
• Module Requirements– Compatible clamping hardware
• Leading Hardware Vendors– Schletter (world leader)
– Unirac
– DPW solar
– SunLink
– Schuco
Schletter - hybrid system
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Flat Roof – BIPV (BAPV)• Description
– Typically very low slope (1/4 :12)
– Built-up Roof (BUR) or Membrane construction
– PV Integrated into roofing materials
• Benefits/Issues – Integral to roofing solution
– Less clutter and obstruction on rooftop
– Most solutions deploy horizontal PV (non-optimal)
– Roof warranty may be too short for ROI
– Potentially less expensive PV installation
• Module Requirements– Involved design integration with
mounting system vendor
– Flexible PV currently preferred
• Leading Hardware Vendors– Solar Integrated
– UniSolar
– Lumeta
– Solar Frameworks
Solar Integrated- Flat Roof BIPV
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Standing Seam Metal Roof – Attached
• Description– Pitched roof for commercial applications
– Standing seam provides convenient attachment point for module mounting
• Benefits/Issues – Simple solution from S5 is widely
deployed
– Reportedly the lowest installation cost for commercial rooftops
– Metal roof does not need to be replaced for life of building
– Weight may be a concern on some metal buildings
– Peel and stick Unisolar solutions also available
• Module Requirements– Compatible clamping hardware
• Leading Hardware Vendors– S5 (module clamp)
– Unisolar (peel and stick)
S5 – standing seam mounting system
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Standing Seam Metal Roof – BIPV• Description
– Pitched roof for commercial applications
– BIPV is pre-mounted to metal roof panels
• Benefits/Issues – Low profile integration creates desirable
appearance on pitched roofs
– Metal roof does not need to be replaced for life of building
– Potentially less expensive PV installation
• Module Requirements– Involved design integration with
mounting system vendor
– Flexible PV currently preferred
• Leading Hardware Vendors– Centria and other Unisolar partners
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Tile/Shingle Pitched Roof – Attached
• Description– Pitched roof for commercial applications
– Utilizes tiles or shingles like residential construction
– PV modules are retrofitted to roof using racking system
• Benefits/Issues – Residential pitched roof racking systems
are applicable
• Module Requirements– Compatible clamping hardware
• Leading Hardware Vendors– Residential mounting system vendors
HelioVolt Confidential and Proprietary
HelioVolt Confidential and Proprietary
Tile /Shingle Pitched Roof - BIPV• Description
– Pitched roof for commercial applications
– Utilizes tiles or shingles like residential construction
– PV is integrated into roofing tiles or shingles
• Benefits/Issues – Residential PV roof-tile products are
applicable
– Potential cost reduction through PV integration has yet to be realized
• Module Requirements– Modified PVIC required
– Certification as roofing material
required
• Leading Hardware Vendors– Suntech
– Q-Cell
– Sharp
HelioVolt Confidential and Proprietary
BIPV Product Requirements• Aesthetics:
– Visual attention – may or may not “blend into building”
– Uniform patterns and colors
– Must complement building design
• Efficiency:
– Highest conversion efficiency per application
• Physical properties:
– Flexibility in size
– Flexible and rigid
• When glass = High quality flat glass
– Thermally or acoustically insulating
• Cost:
– Smart integration
HelioVolt Confidential and Proprietary
BIPV Applications Roofing
– Most common BIPV application today
Sunshades
– Energy conservation and reduced building operating costs
– Cooling load mitigation and glare control
– Easiest retrofit for PV
Overhead glazing (canopies, skylights, atriums)
Curtain wall / Facades
HelioVolt platformfits all formats
HelioVolt Confidential and Proprietary
Standard Product Platform Applied to our Expanded Product Portfolio
High Efficiency PVIC Platform
Commercial Roof Top
Systems
BIPV – spandrels
BIPV – sunshades Parking Structures
HelioVolt Confidential and Proprietary
Other Topics
• Color and Transparency/Translucency
• Flexibility
• Spray on
• AC modules
• Balance of Systems (BOS) costs
HelioVolt Confidential and Proprietary
63
Balance of Systems Costs
Established solar manufacturers are realizing cost reductions across the value
chain and will reduce installed system cost by approximately 50% by 2015
• Note the high level of indirect and labor costs - these are driven by regulatory,
educational and financing hurdles (non-R&D).
20
05
$ p
er
wa
tt in
sta
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20
05
$ p
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