Winter School on
Photonics for Energy
Uwe Zimmermann
Winter School on
Photonics for Energy
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solid state solar cells
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Uwe Zimmermann
Solid State Electronics
Uppsala university
Solid state solar cells.1
Outline.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
This lecture shall give answers to the following questions:
Photovoltaics
History
• Why solar cells?
Semiconductor physics
Solar cells
• What is a solid state solar cell?
• What was the history of the solar cell?
• What is the current state of solar cells?
• What are the important parameters of a solar cell?
• What is limiting the conversion efficiency?
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• What can we expect from current solar cell technologies?
• How sustainable are solar cells?
• Where are we going from here?
Solid state solar cells.2
Winter School on
Photonics for Energy
A glimpse into the future.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Shell energy scenarios to 2050
• Overall energy consumption of the world is expected to
continue growing.
• Future energy production must be affordable and
sustainable.
Solid state solar cells.3
Winter School on
Photonics for Energy
Grid Parity.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
McKinsey Quarterly, June 2008
Solid state solar cells.4
PV potential in Europe.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.5
Winter School on
Photonics for Energy
Direct and diffuse sunlight.
Uwe Zimmermann
Introduction
isotropic diffuse from sky
Solar radiation
Photovoltaics
History
Semiconductor physics
di
ct
re
Solar cells
Electrical parameters
c
cir
ar
l
so
um
CIGS solar cells
di
Multijunction solar cells
e
s
ffu
Other solar cells
Current market
development
diffuse from horizon
ion
reflekt ed
reflect
The future
The global irradiation consists of
• direct sunlight
• diffuse sunlight
• reflected sunlight
Solid state solar cells.6
Direct light in Africa.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• more than 80 % of the insolation in Africa come from direct
sunlight
Solid state solar cells.7
Diffuse light in Europe.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• Up to 64 % of the insolation in northern Europe come from
diffuse sunlight.
• Diffuse sunlight can not be focused or concentrated.
Solid state solar cells.8
Advantages of solar cells.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• Solar cells have no moving parts.
• Solar cells are emission-free during operation.
• Solar cells are silent.
• Solar cell installations can be compact.
• Solar cell installations are scalable.
Solid state solar cells.9
Some history.
Winter School on
Photonics for Energy
Uwe Zimmermann
1839
1876
1954
1958
1970:s
1980
2001
2003
2008
2009
Alexandre-Edmond Becquerel (father of Henry B.)
discovers the photovoltaic effect
the selenium solid-state cell is invented
the modern silicon solar cell is invented at Bell Labs
with 6 % efficiency
the first silicon solar cell in space
the oil crisis leads to an increased interest in solar
cells for terrestial use
first thin film solar cell with > 10 % efficiency
cumulative (1954-2001) worldwide installed
PV power capacity reaches 1 GWp
cumulative worldwide installed PV power
capacity reaches 2 GWp
Spain installs about 2.6 GWp new PV capacity
Germany installs about 3 GWp new PV capacity
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.10
The first modern solar cell.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
• The silicon solar cell was invented by D. Chapin, C. Fuller
and G. Pearson at Bell Labs.
Current market
development
The future
• The transistor had been invented at the same location 7
years earlier.
• 1958 the first commercial solar-cell driven transistor radio
was available.
• Also in 1958 the first solar cells were used in space.
• . . . then for about 30 years not much happened. . . or did it?
Solid state solar cells.11
Winter School on
Photonics for Energy
The first solar-cell satellite.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
http://www.nasa.gov
Current market
development
The future
• Vanguard I, launched 1958-03-17 from Cape Canaveral.
• The fourth artificial satellite, second US satellite.
• 1.47 kg aluminum sphere 16.5 cm in diameter.
• 10 mW, 108 MHz mercury-battery powered transmitter.
• 5 mW, 108.03 MHz transmitter powered by six solar cells.
• The batteries stopped working in June 1958,
the solar cells in May 1964.
Solid state solar cells.12
Teaching in the early years.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• In the early 1960’s Bell Labs introduced a series of
experimental kits.
• Target audience were highschool teachers and their
classes.
• Bell Systems Science Experiment No. 2 contains
everything to make your own silicon solar cells.
Solid state solar cells.13
The solar cell.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• Light can be understood as a flow of photons.
• Photons are absorbed in the solar cell.
• Electron-hole-pairs are created – one per photon.
• Charge carriers drift/diffuse to the contacts.
• An electrical current can leave the solar cell.
Solid state solar cells.14
Winter School on
Photonics for Energy
Photon absorption.
Uwe Zimmermann
conduction band
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Eg
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
valence band
Current market
development
The future
• photons with E < Eg are not absorbed
• photons with E ≥ Eg are absorbed
• an electron-hole pair is created
• photons with E Eg are absorbed
• additional energy is absorbed by the crystal lattice
Solid state solar cells.15
Winter School on
Photonics for Energy
Light absorption in semiconductors.
Uwe Zimmermann
photon flux [1x1021 m−2 s−1 eV−1 ]
wave length [nm]
2500 1500 1000 800
600
Introduction
400
5.0
Solar radiation
AM 1.5
black body 5800K
4.0
Photovoltaics
History
Semiconductor physics
3.0
absorption
Solar cells
Electrical parameters
2.0
CIGS solar cells
Multijunction solar cells
1.0
0.0
0.0
Other solar cells
Current market
development
0.5
1.0
1.5
2.0
2.5
photon energy [eV]
3.0
3.5
The future
Eg
•
•
•
A semiconductor with a bandgap Eg can absorb photons with E > Eg .
A lower bandgap means there are more photons which can be absorbed:
⇒ more electron-hole-pairs ⇒ higher current
⇒ but lower voltage (V ≈ Eg/2q )
A wider bandgap means there are fewer photons which can be absorbed
⇒ fewer electron-hole-pairs ⇒ lower current
⇒ but higher voltage can be achieved
Solid state solar cells.16
Winter School on
Photonics for Energy
Typical semiconductors.
Uwe Zimmermann
photon flux [1x1021 m−2 s−1 eV−1 ]
wave length [nm]
2500 1500 1000 800
600
Introduction
400
5.0
Solar radiation
AM 1.5
black body 5800K
4.0
Photovoltaics
History
CIS
3.0
Semiconductor physics
CGS
Solar cells
CdTe
2.0
Electrical parameters
GaAs
Ge
CIGS solar cells
GaP
Multijunction solar cells
InP
1.0
Other solar cells
Si
0.0
0.0
0.5
1.0
1.5
2.0
2.5
photon energy [eV]
Current market
development
3.0
3.5
Different semiconductors have different bandgaps.
• Silicon is the most common semiconductor today.
• Germanium, GaAs, InP och GaP are used in multijunction
solar cells.
• CdTe, CuInSe2 , CuGaSe2 and the alloy Cu(In, Ga)Se2 are
used in thin-film solar cells.
The future
Solid state solar cells.17
Winter School on
Photonics for Energy
Available current.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Ge
Electrical parameters
CIGS solar cells
Si
Multijunction solar cells
CIS
Other solar cells
InP
Current market
development
CGS
GaAs
CdTe
The future
GaP
Green, M. A.: Solar Cells (1998)
• The maximum current from a solar cell depends on the number
of available photons with E ≥ Eg .
Solid state solar cells.18
Making silicon wafer solar cells.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.19
Winter School on
Photonics for Energy
Silicon solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
image: US DoE
Other solar cells
Current market
development
The future
per m3
Archer; Hill: Clean Electricity from Photovoltaics (2001)
Solid state solar cells.20
Winter School on
Photonics for Energy
Energy bands – two examples.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Cohen et.al., Phys. Rev.141, pp.789-796 (1966)
4
3
3
10
2
102
1
experimental
theoretical
AM1.5 spectrum
101
1.2
1.3
1.4
1.5
0
1.6
absorption coefficient [cm−1]
104
104
2
3
10
102
1
experimental
theoretical
AM1.5 spectrum
101
100
1.3
Current market
development
3
10
photon flux [1x1021 s−1 m−2 eV−1 ]
absorption coefficient [cm−1]
10
100
1.1
5
1.4
photon energy [eV]
1.5
1.6
1.7
photon flux [1x1021 s−1 m−2 eV−1 ]
5
The future
0
1.8
photon energy [eV]
Raykanan et.al., Solid state electronics22, p.793 (1979)
Φ(x) = Φ0 e
Moss et.al., Infrared physics 1, p.111 (1961)
−α x
Solid state solar cells.21
Winter School on
Photonics for Energy
Making thin-film solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
deposition of the back contact
Solar cells
patterning of the absorber layer
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
patterning of the back contact
Current market
development
The future
deposition of the front contact
deposition of the absorber layer
patterning of the front contact
Solid state solar cells.22
Winter School on
Photonics for Energy
Thin-film solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
Archer; Hill: Clean Electricity from Photovoltaics (2001)
CIGS solar cells
Multijunction solar cells
image: Fuji Advanced Techn.
Other solar cells
Current market
development
The future
image: Pacific Solar
image: Uppsala university
per m3
Solid state solar cells.23
Quantum efficiency.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• The quantum efficiency describes the number of
generated electron-hole pairs per incidcent photon.
• The quantum efficiency is wavelength (or photon energy)
dependent.
• The internal quantum efficiency describes the number of
generated charge carriers.
• The external quantum efficiency describes the number of
generated and collected charge carriers.
Solid state solar cells.24
Winter School on
Photonics for Energy
The pn-junction – current transport.
Uwe Zimmermann
Introduction
Solar radiation
Ec
Ec
qVbi
EF
Ev
Photovoltaics
History
EF
Semiconductor physics
Ev
Electrical parameters
Solar cells
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
• Electron-hole pairs are generated.
The future
• Charge carriers diffuse within the neutral regions.
• Electrons drift towards lower energies.
• Holes drift towards higher energies.
• Electron-hole pairs can recombine.
Solid state solar cells.25
Winter School on
Photonics for Energy
Current-voltage characteristics.
Uwe Zimmermann
current power
P
I
Pmax eller Pmp
Introduction
Solar radiation
V
·I
Photovoltaics
with light
=
in dark
ness
P
maximum
power point
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Vmp
voltage
Voc
open circuit
area = Vmp · Imp = Pmp
The future
efficiency η:
η=
Imp
V
Current market
development
Pmax
Pin
fill factor FF :
Isc
short circuit
area = Voc · Isc
FF ≡
Pmp
Voc · Isc
Solid state solar cells.26
Winter School on
Photonics for Energy
IV-curve – The one-diode model.
Uwe Zimmermann
Introduction
Rseries
+
Solar radiation
Photovoltaics
Ilight
D
History
Rshunt
Semiconductor physics
-
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
• A good solar cell is described by the one-diode model.
• This model consists of
• the pn-junction diode D
• a current source with the light-generated current Ilight
• a series resistance Rseries
• a shunt resistance Rshunt or shunt conductance Gshunt
Other solar cells
Current market
development
The future
• The current-voltage characterstics of this circuit is given by the implicit
equation
I(V ) = Idiode (V ) − Ilight + Gshunt V − Rseries I(V )
• Often the current density J = I/area, [J] = A cm−2 is used.
Solid state solar cells.27
IV-curve – Assumptions.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• The simulated IV-curves on the following slides are
calculated for a 100 cm2 silicon solar cell with the following
assumptions:
• ideality factor A = 1.0
• saturation current density J0 = 4 × 10−13 A cm−2
• light-generated current density Jlight = 30 mA cm−2
Solid state solar cells.28
Winter School on
Photonics for Energy
IV-curve – Influence of the series resistance.
Uwe Zimmermann
current power
P
I
Introduction
Solar radiation
Photovoltaics
History
voltage
V
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Rshunt
Ω
1 000 000
Rseries
mΩ
1
2
5
10
20
50
100
Voc
V
0.650
Isc
A
3.000
Vmp
V
0.565
0.561
0.555
0.541
0.512
0.451
0.359
Imp
A
2.864
...
...
...
...
...
...
Pmp
W
1.618
1.608
1.588
1.544
1.450
1.254
0.879
FF
%
83
82
81
79
74
64
45
η
%
16.2
16.1
15.9
15.4
14.5
12.5
8.8
Solid state solar cells.29
Winter School on
Photonics for Energy
IV-curve – Influence of the shunt conductance.
Uwe Zimmermann
current power
P
I
Introduction
Solar radiation
Photovoltaics
History
voltage
V
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Rshunt
mΩ
10 000
5000
2000
1000
500
200
100
Rseries
mΩ
1
Voc
V
0.647
0.646
0.645
0.641
0.632
0.586
0.300
Isc
A
3.000
Vmp
V
0.563
0.562
0.560
0.553
0.530
0.324
0.150
Imp
A
...
...
...
...
...
...
...
Pmp
W
1.586
1.549
1.471
1.305
0.965
0.483
0.223
FF
%
82
80
76
68
51
28
25
η
%
15.9
15.5
14.7
13.1
9.7
4.8
2.2
Solid state solar cells.30
Cu(In, Ga)Se2 solar cells.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.31
Parasitic light absorption.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.32
Winter School on
Photonics for Energy
Parasitic light absorption.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
160
History
140
Semiconductor physics
Solar cells
120
current [mA]
Electrical parameters
100
3102 Zn(O,S)
3126 CdS
CIGS solar cells
80
Multijunction solar cells
60
Other solar cells
40
Current market
development
20
The future
0
0
2
4
6
voltage [V]
8
10
12
Solid state solar cells.33
Winter School on
Photonics for Energy
Upper limit for efficiencies.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Si
InP
GaAs
Electrical parameters
CdTe
CIGS solar cells
CIS
CGS
Multijunction solar cells
Other solar cells
GaP
Current market
development
The future
Ge
Green, M. A.: Solar Cells (1998)
• The Shockley-Queiser limit is based on thermodynamic
principles.
Solid state solar cells.34
Winter School on
Photonics for Energy
Ever increasing efficiencies?
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://www.nrel.gov/
• The efficiency is generally limited by
• basic semiconductor physics
• technological processes
• electrical losses
Solid state solar cells.35
Winter School on
Photonics for Energy
Multijunction solar cells.
Uwe Zimmermann
Eg1
Eg2
Eg3
Introduction
Solar radiation
Photovoltaics
E2
History
Semiconductor physics
E1
E3
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
• a conventional solar cell has one absorber with
a single bandgap Eg1
• photons with energies E ≥ Eg1 are absorbed
• photons with energies E < Eg1 are transmitted
⇒ in a multijunction solar cell several absorbers
are stacked on top of each other
Solid state solar cells.36
Winter School on
Photonics for Energy
Multijunction solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://sunlab.site.uottawa.ca
Solid state solar cells.37
Winter School on
Photonics for Energy
Multijunction solar cells.
Uwe Zimmermann
+
I1
V1
I
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
V
Solar cells
Electrical parameters
+
I2
V2
I
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
V
+
I3
V3
The future
I
V
Solid state solar cells.38
Winter School on
Photonics for Energy
Multijunction solar cells.
Uwe Zimmermann
Introduction
I
Solar radiation
Photovoltaics
+
History
V1
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
+
Other solar cells
V2
Current market
development
The future
I
+
V3
V
Solid state solar cells.39
Triple junction solar cells.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
http://www.ise.fraunhofer.de
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://pvlab.ioffe.ru
Solid state solar cells.40
Winter School on
Photonics for Energy
Multijunction solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://www.concentrix- solar.de/
http://psilab.ucsd.edu/
Solid state solar cells.41
Winter School on
Photonics for Energy
Active optics.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
images: Prism Solar
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.42
Winter School on
Photonics for Energy
Monograin solar cells.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Meissner, D.: Monograin Solar Cells – Time to Market
Solid state solar cells.43
Winter School on
Photonics for Energy
A growing industry.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://www.iea- pvps.org
The cumulative installed solar cell power in IEA-reporting countries.
• Since the year 2000 the installed capacity has doubled
every second year.
• Today the majority lies within grid-connected systems.
Solid state solar cells.44
Winter School on
Photonics for Energy
Payback.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://www.iea- pvps.org
• On a system level solar cell installations take less than
2 years to break even (energy payback time).
• The expected lifetime for a solar cell installation is more
than 20 years.
Solid state solar cells.45
Cost development for solar cell systems.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
http://www.iea- pvps.org
Cost development for solar cell systems since 1997.
• The price for solar cells has declined from 60 USD/watt (1976) to
less than 4 USD/watt (2008).
• However, since 2000 the decline has slowed down.
Solid state solar cells.46
Winter School on
Photonics for Energy
Brandis/Waldpolenz.
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
UZ 2008
http://www.solarserver.de
Current market
development
The future
• Installed on a discontinued military air field in eastern Germany.
• Planned to become the world’s largest PV power plant in 2008
with 40 MW.
• About 500 000 cadmium-telluride thin-film modules from
FirstSolar.
Solid state solar cells.47
Size does matter.
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Solid state solar cells.48
The Future?
Winter School on
Photonics for Energy
Uwe Zimmermann
Introduction
Solar radiation
Photovoltaics
History
Semiconductor physics
Solar cells
Electrical parameters
CIGS solar cells
Multijunction solar cells
Other solar cells
Current market
development
The future
Conclusions
• In order to make an impact, we need to generate some TW of
electricity by means of solar power.
• A solar cell needs to
• capture light
• separate charge carriers
• extract charge carriers
Solid state solar cells.49