The document summarizes a presentation about integrating solar photovoltaics and batteries. It discusses the motivation to make solar electricity more economical and reliable by reducing costs through integrated PV-battery devices. The presentation outlines challenges with solar and battery economics. It proposes several conceptual designs that combine PV materials with battery electrodes or electrolytes to potentially lower costs by 50% compared to separate systems. Questions are asked about costs, timelines, and measuring progress of a proof-of-concept.

1. ENSC S-175 Presentations
Integrated Solar Photovoltaics-Battery
Devices
August 8, 2011
Burhan Saifaddin ?
bks@mit.edu
All rights reserved (Confidential)
ENSC S-175 Presentations

2. Harvard University
Outline
•Motivation and Benefit to Society
•When will PV become competitive ?
•Why PV-battery integration is useful ?
•Project Description and Goals
•Battery economics problems
•Proposed Designs (Confidential)
•Conclusion
•Questions
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3. Harvard University
Benefits to Society
Meeting huge Energy demand Sustainably.
2010 15 TW ; 2050 30 TW (peak) Figure adopted from
woodruffcenter.org
Hedge against the risk of Global warming.
Energy Security.
Economic growth. Potentially a Trillions of dollar industry.
Reducing energy costs to increase human development.
Figure adopted from
Wikipedia
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4. Harvard University
Benefits to Society
In most of these areas
Solar insolation
1 out of 5 in the world
> 1.5 MWh/m2/year
do not have
access to electricity
AAAS voted electrification to be the most important technology developed in 20th century.
Electrification affected productivity far more than IT (at least up to 1990 but IT is dependent on
Electrification).* * David, P. (1990). "The dynamo and the computer: An historical perspective on the modern productivity paradox."
The American Economic Review: 355-361.
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Global Oil Energy Problem
Current oil consumption is equivalent to 3.2 million barrel a
day in electricity, water, transportation and industry.
Demands have increased by 27% over the last three years.
2032 Electricity demands will trouble ; additional 80 GW
Very challenging politically to decrease consumption rate.
Data is based on a speech by Hashim Yamani, president of
King Abdullah City for Atomic and Renewable Energy, at
GCF 2011.
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6. Harvard University
When will Solar electricity be economically competitive to Coal and Gas ?
1 out of 5 in the world
do not have
access to electricity
5 c/kWh
1 $/Wp
~ 50B dollars industry based on generous Government subsides and ‘’biased’ regulations
www.mckinsey.com/clientservice/ccsi/pdf/economics_of_solar.pdf
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What is the problem, why is it hard?
•Generate economically competitive electricity form the
sun sustainably.
Sun is the major source of energy for life and every
service on earth but
3.Sun intensity is dilute 1-3 MWh/m2/day (my 2-bedroom
apartment consumes 20-26 MWh/m2/day )
• High installation costs
• Need high solar conversion efficiency and lifetime.
2. Sun is intermittent
• Need battery for storing electricity. Too expensive.
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8. Harvard University
Current Photovoltaics (PV) solar cells comparisons
Minimum installed system cost for:
Rooftops 6-8 $/Wp,
Utility cost 5 $/Wp, DOE goal to reach 1$/Wp (without batteries)
DOE, 2011 8

9. Harvard University
Current PV technology economics:
Photovoltaics (PV) learning curve => installation cost is a problem !!
Learning curve for the cost of PV systems, module prices, and BOS cost. Source Navigant Consultant
Adopted from DOE [http://www1.eere.energy.gov/solar/pdfs/dpw_chu.pdf]
Burhan Saifaddin Presentation | ENSC S-175 | August 8, 2011
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10. Harvard University
Why battery integration is
useful ? Check Roof PV cost breakdown
Roof top PV system without battery
Installation cost of module is
increasingly the dominant cost
Design Goal :
2.Make Solar electricity less
intermittent
3.reduce Installation cost for
installed PV systems that are
reliable 247
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Proposed Design for Integrated PV-Battery Device
 Investigate computationally PV active materials for Battery electrodes (Anode, possibly
cathode) or electrolyte.
• Solar cells insolation 1- 3 MW/m2/year so No need for high powered battries/m2  Cheap
• Materials for PV and Batteries need to be abundant and cost effective.
Challenge: Electrons flow from High work function
Battery PV
Anode V+ Active PV layer
e- flow e- flow
Cathode V- Holes+ flow
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12. Harvard University
Proposed Design for Integrated PV-Battery Device
 Investigate computationally PV active materials for Battery electrodes (Anode, possibly
cathode) or electrolyte.
• Solar cells insolation 1- 3 MW/m2/year so No need for high powered battries/m2  Cheap
• Materials for PV and Batteries need to be abundant and cost effective.
 Need to be: (1) electrolyte and electrode inconsumable (as in new Li and NI-NH batteries. (2)
electrode have reasonable energy storage volume density. (3 ) PV-compliable voltage
difference between electrodes )
Battery PV

Anode V+ Active PV layer
Electrolyte
e- flow e- flow
PV Absorbers
Cathode V- Holes+ flow
Challenge: Electrons flow from High work function
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13. Harvard University
Proposed materials combinations (Confidential):
• Dye Synthesized Solae Cells: two electrodes and electrolyte.
• Silicon air batteries with PV.
• Solution processed PV and transparent batteries
 IC started the Semiconductor revolutions. Noyce and Kilby 1969.
Battery PV
Anode V+ Active PV layer
e- flow e- flow
Cathode V- Holes+ flow
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(Confidential) Solution processed PV and transparent batteries:
Dye, Organic, CIGS
Photovoltaics solar cells are made from semiconductors whether organic and inorganic.
C O NTE NTS 9
(ii)
(iii)
energy
(i)
(iv)
(v) (vi)
donor
acceptor
anode bulk heterojunction cathode
F i g u r e 3 . F ro m li g h t a b s o rp ti o n to p h o to c u rre n t i n a bTransparentti lithium-ion batteries. Y Yang, Yi Cui et al,
u lk h e te ro ju n c o n s o la r c e ll. L e f t:
Solution Processed pOrganice w , ri g h t: Cells fi e d e n e rg y d i a g ra m ( b i n d i n g e n e r g i e sPNAS,i to n s 2011
f ro m a k i n e ti c o i n t o f v i Solar s i m p li f o r e x c June
a n d p o la ro n p a i rs a re n o t s h o w n ) . ( i ) s i n g le t e x c i to n g e n e ra ti o n f ro m a n a b s o rb e d p h o to n i n
th e d o n o r m a te ri a l. ( i i ) e x c i to n d i f f u s i o n to th e a c c e p to r i n te rf a c e . ( i i i ) e x c i to n d i s s o c i a ti o n
Page 14 b y e le c tro n tra n s f e r to th e e leBurhan n e g a ti v e a c c e p| to r mS-175 | c August. 8, 2011 ) s e p a ra ti o n o f th e s ti ll
c tro Saifaddin Presentation ENSC o le u le s ( i v

15. Harvard University
(Confidential) Silicon air batteries with PV as the top electrode
Photovoltaics solar cells are made from semiconductors whether organic and inorganic.
Potential Battery Technology:
Silicon Air
Metal-air battery with easily
Si Solar Cell
removable anodes
AJ Niksa, MJ Nikasa, JM Noscal
- US Patent 4,950,561, 1990
Silicon–air batteries.
Electrochemistry CommunicationsVo
11, Issue 10, October 2009,
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(Confidential) Dual Dye-sensitized solar cells and battery
Dye Synthesized Solar Cell is similar to battery design but problem with electron flow
direction ?
Dye-sensitized solar cells, Michael Grätzel, EPFL
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17. Harvard University
Other Potential low cost, Abundant, easy to process PV Materials
that possibly can be integrated into batteries
MIT Energy Workshop on Critical Elements for New Energy
Technologies | April 29, 2010
17
C. Wadia, A. Alivisatos, D. Kammen, |Environ.| Sci. Technol 43,
Burhan Saifaddin Presentation ENSC S-175 August 8, 2011

18. Harvard University
Why have not people done yet ?! Battery Economics (and possibly current
materials physics !!).
However PV Integration might lead to 50% cost reduction.
BCG report:
"Batteries for electric cars
challenges opportunities
and the outlook to 2020"
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19. Harvard University
Current High powered Li-ion batteries will still be too expensive. New low power
density battery designs are needed to commercialize the technology
BCG report:
"Batteries for electric cars
challenges opportunities
and the outlook to 2020"
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20. Harvard University
Batteries Economics: We need new cheap , LOW performance
battery designs (No need for high performance)
BCG report:
"Batteries for electric cars
challenges opportunities
and the outlook to 2020"
Low performance
=> Less battery cost
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21. Harvard University
Additional Remarks about the proposal
How much will it cost? Delivered electricity has to economically competitive with
other sources of electricity without subsides 10-5 c/kWh in most places.
How long will it take?!
How will progress be measured? Proof of concept first.
Broader Impacts Criterion.
Need Seed fund of 100,000 $ to build a proof of concept.
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22. Harvard University
Conclusion:
What is unique in this approach and why is will succeed?
• Potential able to reduce installed battery • Empower Solar Cells and make them
connected systems by 50%. more reliable. Work at night, cloud, sand ,
• Reduce complexity of future smart grids. rain and in off grid locations for 247.
• Reduce need for biased government
regulations.
• Expected to reduce the installation cost
of Battery connected PV.
• Analogues to IC revolution By Noyce
and Kilby started in 1959.
• Drawback: Increase in PV cost
HOWEVER PV module cost is less than
20% of the total PV system cost.
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Questions

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24. Harvard University
Questions
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Questions Fierce Race to develop new PV and Batteries (not include here)
•
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26. Harvard University
Average PV Installed Cost 2009
http://cleantechnica.com/ 26
Burhan Saifaddin Presentation | ENSC S-175 | August 8, 2011