Advances in Photovoltaic PV Technology

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Advances in Photovoltaic (PV) Technology
Bolko von Roedern

• National Center for Photovoltaics
• National Renewable Energy Laboratory
• Golden, Colorado USA
• NREL Seminar, Innovation for our Energy Future,
  April 10 2008

039837
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Acknowledgements

• Past Thin Film program and interactions with
  subcontractors
• Martha Symko Davies for SAI material
• Long-time SERI/NREL support and feedback (joined
  SERI in 1983)

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Presentation Outline

• PV markets through 2007
• PV technologies that are in production and
  emerging.
• PV in the renewable energy portfolio
• Assessment and comparison of current PV
  Technologies

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PV in 2007

• PV NEWS, Photon International, and Navigant
  Consultants published reviews of 2007 PV market
  activities
• Around 3700 MW of PV was produced in 2007 (world,
  266 MW thereof in the US, _at_10 efficiency, 37 km2
  of modules)
• Thin Film PV reached a market share of gt10 world
  wide, over 60 of US-produced modules.
• US-based Thin Film PV producer First Solar ranked
  among the top 6 World manufacturers
• China and Taiwan produced 32 of World total

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The US PV companies in 2007

• (1) First Solar shipped 120 MW, cap 08 150 MW
• (2) Uni-Solar Ovonics 48 MW, cap 08 120 MW
• (3) Solar World (Shell) 35 MW, cap 08 100 MW
• (4) Evergreen Solar 16.4 MW, cap 08 86 MW
• US total 266 MW, cap 08 616 MW (
• Slide considers MW produced in US only

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Concentrator Technologies

• Technologies are ready to deliver
• High and low concentration schemes are possible,
  low concentration may be possible without
  tracking
• Systems may require some maintenance, should only
  be deployed in areas with adequate direct solar
  resource.

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Concentrator technology

• Status 2007 initial commercial installations
• Move from using Si cells towards III-V cells
• A great way to add capacity, makers of
  high-efficiency cells exist (Emcore and
  Spectrolab)
• Spain may become initial market
• Until real markets exist, cost/performance of
  such systems relies on estimates.

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Dilemma

• Solar Energy is the only renewable energy
  technology with enough resource to produce tens
  of terawatts, but currently is the most costly
  electricity producer (needs to grow 1000-fold
  over 2006 production, storage vs. international
  grid options)
• Challenge Grow Solar from a very small base,
  simultaneously add other renewables that are more
  resource limited but faster-growing.

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Dilemma

• Lower cost renewable energies (wind, biomass)
  dont have the resource-base to cover current
  energy needs.
• Energy harvest
• biomassltwindltsolar electric

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Germany through 2006
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Photon International 2010 PV Market Estimates
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DOE/NREL PV contract programs

• In the past Thin Film Partnership and PVMatRD
• Since 2006 Solar America Initiative

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Presidents Goal for the Solar America Initiative
(SAI)Making Solar Cost-Competitive Nationwide by
2015
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PV RD pipeline will support technologies/companie
s, with funding opportunities calibrated to
maturity
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Photovoltaic Technology Incubator Objectives

• Explore the commercial potential of new
  manufacturing processes and products
• Promote the development of a diverse set of PV
  technologies which cover a variety of target
  markets including residential, commercial, and
  utility power generation.
• Investigate the scale-up potential of promising
  technology which has already be proven on a small
  scale.
• Foster innovation and growth in the domestic PV
  industry
• Provide U.S. small businesses with a chance to
  expand quickly in a rapidly maturing industry.
  Successful projects will position companies to
  apply into the second phase of the larger,
  Technology Pathway Partnerships which focuses
  on full cost reductions to make PV
  cost-competitive by 2015.
• Establish an efficient and cyclic funding
  opportunity
• Funding is structured so that companies receive
  funding from the Department only upon successful
  performance of pre-specified new hardware.
• Provide funding opportunities for new applicants
  every 9 months.
• Perform a stage gate review of funded incubator
  projects at 9 months.

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Project Development Focused on Improvements at
the Module Level

• Project development is focused on a limited
  number of high impact technical improvement
  opportunities at the module level that lie on the
  critical path to scaling-up their technology to
  full manufacture.
• Full system cost reductions including
  installation, inverters, and balance of system
  components is the focus the Technology Pathway
  Partnerships project currently in phase 1.

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Photovoltaic Technology IncubatorDetails of
Selected Projects

• Incubator projects will significantly expand and
  diversify domestic market ready PV
  technologies
• Establish up to 1 GW of annual manufacturing
  capacity by 2010 of technology which is not
  commercially produced today.
• Position 10 U.S. companies competitively among
  world PV manufacturers by 2010.
• Projects include a diverse set of technological
  approaches
• Inexpensive and Thin Film Si
• Low and High Concentration

• Innovative thin film manufacturing
• Low Cost Multi-Junction Cell Production

• Selected PV Technology Incubator Projects
• AVA Solar
• Blue Square Energy
• CaliSolar
• EnFocus Engineering
• MicroLink Devices

• Plextronics
• PrimeStar Solar
• Solaria
• SolFocus
• SoloPower

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DOEs Portfolio Balances Technology, Maturity
Risk
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Guidance for selection

• Lowest-cost levelized cost of electricity
• Use SAM to develop appropriate LCOE cost models
• Identify target markets and cost (a) residential
  (rooftop), (b) commercial, (c) utility scale

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PV Technologies

• Following slide shows all of them
• Will come back to ordinate (not abscissa) values
• Need to see where technologies are and compare
  relative value

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Near-term PV technologies

• standard wafer/ribbon Si
• amorphous silicon
• -----------------------------------------------
• Non-standard wafer Si
• a-Si (nc-Si) spectrum splitting multijunctions
• CdTeCIGS
• ------------------------------------------------
• Next generation OPV and DSC
• ------------------------------------------------
• Concentrators at all of the above levels

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A Rigorous Scheme for Comparing the Near-Term
Potential of Different PV Module Technologies

• We needed to asses real efficiency numbers,
  knowing that champion cell results and commercial
  product are well documented.
• Define the c/c ratio as the ratio between
  verified (stabilized) champion cell efficiency
  and commercial product efficiency
• Assume that at some point in the future, c/c
  values of 0.8 will be achieved for all
  technologies
• Project cost effectiveness (/Wp) assuming that a
  thin-film module will avoid Si wafer cost,
  otherwise cost the same as Si modules.

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Web Survey of (best) Flat Plate Commercial
Modules (04/08)
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Future commercial module performance based on
todays champion cell results and a c/c-ratio of
80
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Summary

• Champion cell results can predict commercial
  product performance
• Without a 15 efficient total-area stabilized
  cell, there will be no commercial 10 low-cost
  module product.
• a-Si/nc-Si will need greater laboratory
  efficiency to be competitive with competing
  technologies in the long run
• Near term, all technologies are competitive, thin
  film modules with efficiencies gt9 will lead the
  way towards lower module prices.
• Concentrator systems, technically ready, would be
  promoted if a PV growth rate gt40/per year was
  mandated.

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gt20 efficient commercial cells will only be
possible with non-standard processing (HIT,
point, PERL contacts) and while using very-high
lifetime wafers (gt500 microseconds) only
achievable with mono-crystalline wafersThere is
little or no benefit (for cell performance)
processing solar grade wafers using non-standard
processing, or using higher lifetime wafers and
standard processing
Si-PV predictions
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Solar grade feedstock (e.g., fluidized bed
process) may not be good enough to make
high-lifetime mono-Si wafers for 20 commercial
cellsThe debate should not be mono vs multi-Si
but rather standard vs non-standard
(high-liftime mono)Cost predictions suggest
that very high efficiency will win over
standard processing. Thin films with eff. gt11
and concentrators gt25 are also very competitive.
Longer-term Predictions
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Commercialization and Systems

• Thin-Film Modules are used for some large field
  installations in Germany
• For a Module cost per Watt should be lt70 of
  x-Si modules, installed thin film system costs
  will be less than for x-Si systems
• Glass-to-glass(foil) laminates most suited for
  large field installations

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BIPV and Special Product
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40 MW Thin Film CdTe Solar Field
Total Project Price Euro 130 MillionPV System
Price Euro 3.25 / WattsCompletion
Date December 2008
Under Construction
First Solar / Juwi Solar
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US-owned, US manufactured modules by technology,
crystalline Si and Thin Films (incl. a-Si)
1999-2008
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PVNews reported US production thru 2007
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Conclusions

• Who will win the PV race, non-standard Si,
  standard Si, or thin-films?
• U.S.-based commercial thin-film PV module
  production reached a share of 29 in 2005, 45 in
  2006 in the U.S., over 60 in 2007, indicating
  much more rapid growth than crystalline Si PV
• Commercial module performance is increasing based
  on current knowledge. Todays RD will lead to
  future product improvement
• A sustained growth of PV technology gt40/year
  will require more resources than are currently
  available world-wide.