Transcript PV Technologies: Rural perspectives

PV Technologies: Rural perspectives
Prof. Hari M. Upadhyaya
Department of Mechanical Engineering
School of Engineering & Physical Sciences
Heriot Watt University
Edinburgh- EH14 4AS
Phone: 0131-451 4381
Email: [email protected]
The Photovoltaic (PV) word is composed of two terms: Photo - Photon which
means "light" and Voltaic from "Volt" which is the unit for electric potential
Solar Thermal energy
and Solar Photovoltaic
energy?
The photovoltaic solar energy
system converts sunlight directly
into electric power to run
lighting or electric appliances.
Both use the irradiance of the
sun although the technology is
quite different.
The solar thermal energy system
generates and produces heat.
This energy can be used to heat
water or air in buildings, etc.
Source: European Photovoltaic Industry Association (EPIA) - FAQ.htm
Courtesy of:
PV Technologies
First Generation
crystalline silicon (mono & multi)
This will be the PV-backbone technology and
leader of the BIPV sector.
module efficiency:
13%
20%
Second Generation
thin film: a-Si, CdTe, CIGS
Viable competitor in BIPV and roll-to-roll
process for flexible substrates.
module efficiency:
9%
15%
Disruptive/ New Generation
dye cell and organic
Initially niche market oriented, but breakthroughs could push field
towards mass power generation.
module efficiency:
4%
10+%
new concepts
2000
$0.30/kWh
2010
2020
2030
$0.05/kWh
Solar module production for different technologies
CIGS is emerging
CdTe is leading
a-Si:H: Several manufacturing plants
worldwide
Silicon is, and will remain,
the main technology in
PV for the next 20-30 years!
EPIA expects thin film shares will grow:
20% in 2010 with about 4 GW
25% in 2013 with about 9 GW
4
Swiss Federal Laboratories for Material Testing and Research
Si solar module
Si wafer cells batch processed
and later on individually
connected with wires for
module making on rigid
supporting plate
Thin film solar module
Stack of several layers are
uniformly deposited on large area
substrate (glass, metal, polymer)
and module is developed by
monolithic interconnection
Turn-key production plant suppliers:
Oerlikon solar, Applied Materials, ULVAC, and
others
Strong benefit from synergy with flat panel display business
Wafer vs Thin Films
Mono/Poly-crystalline
Silicon or
III-V compounds
Thin Film Solar Cells
• Amorphous Silicon (a-Si)
• Cadmium Telluride (CdTe)
• Copper Indium Gallium Diselenide (CIGS)
• Thickness: > 200 µm
• Thickness: 2 - 10 µm
• Area limited by wafer size
• Large area deposition
• Rigid
• Flexible Substrates
• Complex Modul Integration
• Monolithical Module Integration
 Expensive
 Low cost potential
CdTe Thin film Solar Cells
+
Back Contact
• Cheapest of all PV technologies
Metal
Buffer Layer
p+ - Te-rich Layer
Front
Contact
p - CdTe
absorber
n - CdS
window
TCO (FTO)
Glass substrate
Irradiation
superstrate configuration is used
for high efficiency devices
State of art efficiency 17.3%
•Modules 67 cents/ Wp
•Lowest payback time <2 yrs
•First Solar is largest thin film PV
manufacturing company
Suffers from Cd toxicity issues
Limitation of Te in the earth crust
-
Module
Commercial Modules
First Solar (USA)
10.9%
efficiency
ca. 75 Wp
Calixo (Q-cells), AVA Solar,
CTF Solar (former ANTEC),
Arendi, ....
Fast growing production capacity: ~20 MW (2004), 170 in 2007, ~1000 MW by
2010.
First Solar production cost 0.87 $/W reported in 2009 (lowest cost thin film
PV)
No environmental & health risks from CdTe PV modules (Sites: NREL, BNL, First
CIGS Solar Cells
~0.5 m
~100 nm
~50 nm
n+ type ZnO:Al
i-ZnO (intrinsic)
n-type CdS
~ 2m
p-type Cu(In,Ga)Se2
~ 1m
Mo
Substrate
• CIGS solar cells are best of all
Thin Film PV technologies with
Efficiencies > 20% on glass
and
•18.7 % on flexible polymer foils
making them ideal for space
applications
• Complex compositional adjustments for good electronic quality
of the material
• Scarcity issues with In and Ga materials anticipated bottleneck
for volume production
Excitonic Solar Cells: Architecture
Nanocrystalline Sensitizer
TiO2 film
dye
I- / I2 based electrolyte
Platinised TCO
Light
TCO
coated
glass
coated glass
Light
Glass
II
ITO
3
Organic semiconductor(BHJ)
Load
External circuit
Metal contact (Al, Ca, Mg)
Electrons
Nanocomposites of TiO2/Ru-dyes are formed
based on Photosysnthesis approach
Bulk heterojunctions P3HT:PCBM are formed
using donor/acceptorApproach (Tang 1986)
• These may be regarded as first successful nanostructured device.
• All processing steps are non-vacuum generally solution processed
• TiO2 films from doctor blade, screen printing methods.
• Lowering of cost potential further but suffer from stability issues
Facts:
• Solar is the fastest growing
renewable energy technology. Global
investment in solar was the order of
$86bn in 2010, a 52% increase on
2009. In terms of investment, it
already dwarfs all other renewable
technologies apart from wind, and is
indeed likely to overtake wind very
shortly.
Bloomberg New Energy Finance
• Global PV capacity has been increasing at an average annual growth rate
of more than 40%
• by 2050, PV will provide around 11% of global electricity production
corresponding to 3 000 gigawatts of cumulative installed PV capacity and
avoid 2.3 gigatonnes (Gt) of CO2 emissions per year.
• PV will achieve grid parity – i.e. competitiveness with electricity grid retail
prices – by 2020
• Potential of reducing costs further.
Expectations
• Requires Governments and industry must increase R&D
efforts supporting longer-term technology innovations
• Implement effective and cost-efficient PV incentive schemes
• appropriate financing schemes, in particular for rural
electrification
• policies to build confidence for investments in manufacturing
capacity and PV deployment
Incentives by UK government
• Feed In Tariff (FIT)
- The Renewable Energy Sources Act (feed-in law) – very successful
in Germany
- More than 2/3 of that capacity has been installed through a
residential capital cost buy-down program
- The newly introduced government incentives only in April 2010 on
feed-in-tariff have resulted in 38000 PV installations in the UK by
the end of May 2011.
- This emerging UK solar sector has resulted in a significant amount
of employment in the UK with over 2,400 MCS installers accredited
to date with 2500 new jobs. An estimate from GreenPeace/ EPIA
suggests this is likely to increase to around 15,000 by 20145.
• UK renewable heat incentive
• sustainable energy by design: a guide for sustainable communities
Challenges
• Costs :
The cost of PV electricity still is far too expensive as compared to conventional
means
• Planning
- Assessing the demand – single house or entire community
- System sizing
- Technical aspects such as inverters, batteries etc.
• Safety and building regulations
- Building Regulations 2004 apply in Scotland
- Local authorities need to be notified of any electrical work or domestic
installation
- http://www.legislation.gov.uk/ssi/2004/406/contents/made
• Help:
- Photovoltaics in Buildings - Guide to the installation of PV Systems 2nd Edition
- Good Practice Guide - Managing the Installation of PV Systems (BERR
Summary
• PV is an established industry with fastest growth
> 40% for last decade
• Good for distributed and small scale deployment
suitable for remote/ rural locations
• Potential for further cost reduction with R&D
towards achieving grid parity
• Needs goverment incentives
• Requires awareness amongst the masses about
the existing and competing technologies
Acknowledgements
Prof. Ayodhya N. Tiwari, EMPA, Switzerland
Prof. James Durrant, Imperial College
Prof. Michael Graetzel, EPFL, Switzerland
Dr. Saif Haque
Dr. Jake Bowers
Mr. Chandan Bhardwaj