Concentrator Photovoltaic installations
based on III-V-heterostructure solar cells
V.M.Andreev Head of Photovoltaics Laboratory of the Ioffe Physical-Technical Institute,
26 Polytekhnicheskaya str. 194021, Saint-Petersburg, Russia
Phone: (812)297-5649 Fax (812)297-1017
e-mail: [email protected], http://pvlab.ioffe.ru
Solar cell chip with
dimensions of
2 mm x 2 mm
Concentrator module
0.5 m x 0.5 m based
on 144 submodules
Concentrator PV array (1m2)
based on 576 submodules
Concentrator PV installation
based on 2592 solar cells and
Fresnel lenses
http://www.ioffe.ru
http://pvlab.ioffe.ru
Early developments of III-V-heterostructure solar cells and PV
installations at the PV Lab of Ioffe Institute
Solar cells based on AlGaAs/GaAs heterostructures were at first proposed and fabricated at the Ioffe
Institute in 1969 under the direction of Prof.Zh.I.Alferov. Owing to their higher efficiency and improved
radiation hardness, nanoheterostructure solar cells are used widely in space. Heterostructure solar
cells with total area of 70 m2, fabricated at the Enterprise “Kvant” using technology developed at the
Ioffe Institute, were installed on the Russian space station “Mir” and on the other spacecrafts.
“Mir” station with two
wings equipped with
heterostructure solar
cells
Module with
small (1cm2)
lenses (1989)
CPV installation based on
mirrors (1981).
Rightmost: Prof. Zh.Alferov,
Nobel Prize laureate
CPV installation
based on Fresnel
lenses (1986)
Terrestrial concentrator PV installations developed at Photovoltaics Laboratory (http://pvlab.ioffe.ru)
of the Ioffe Institute since 1980 consist of concentrator photovoltaic modules arranged on sun
trackers. The advanced concentrator module consists of a frontal concentrator panel, which is a
parquet of Fresnel lenses, and a rear power generating plate, on which multijunction (MJ) solar cells
with secondary concentrating optical elements are placed in the focal points of the lenses.
pAl0.8Ga0.2As
p+GaAs
p-GaAs
n-GaAs
n-GaAs/AlAs
12 periods
1 m μ n-GaAs
GaAs- n++
Contact layer
AlInP-n Window
GaInP-n Emitter
GaInP-p Base
(Al)GaInP- p+ BSF
Tunnel Junction
Tunnel Junction
AlGaAs- n Window
GaInAs- n Emitter
GaInAs- p Base
(Al)GaInP- p+ BSF
Tunnel Junction
Tunnel Junction
GaInAs- n Buffer
GaInP- n Window
n-Ge junction
р-Ge – substrate
GaInP/GaAs/Ge 3J cell structure
MOCVD installation AIX200/4 for
fabrication of multijunction solar cells
0.5 m μ
p+ GaAs p-AlGaAs n-GaAlAs
p n Bragg
reflector
n+ GaAs
GaAs AlAs/GaAs
SEM and STM images of AlAs/GaAs Bragg Reflector –
part of multijunction solar cells
GaInP/GaAs/Ge 3J solar cell developed at IOFFE Institute
n-AlInP “window”
n-InGaP emitter
p-InGaP base
p-AlInP BSF
GaAs
средни
й элеме
нт
(1,40 eV)
Reduction of optical losses:
grid contact, antireflecting
coating
Reduction of losses
at the interfaces by
using tunneling
p-n junctions
Reduction of contact
losses
Reduction of losses from
the charge carrier surface
recombination
Reduction of bulk
recombination losses:
rear barriers
Matching of the lattice
parameters and
application of
nanodimensional layers
Limitation of charge
carriers
Reflection of photons
Matching of photocurrents
n-InGaP “window”
n-GaAs emitter
p-GaAs base
p-InGaP BSF
n-Ge emitter
Conversion of the
short-wavelength part
(400-670nm) of the solar
spectrum
Conversion of the
middle-wavelength part
(670-900nm) of the solar
spectrum
Conversion of the
IR part (900-1650nm) of
the solar spectrum
p-Ge base
Sunlight
1 ?
m
20 nm
III-V multijunction solar cell technology at Ioffe Institute
SIMS distribution of elements: P, As, In, Al, Ga, Zn, C, Si in
AlGaInP/GaInP/GaAs tandem cell structure
0 200 400 600 800 1000 1200 14001E14
1E15
1E16
1E17
1E18
1E19
1E20
1E21
1E22
1E23
ZnZn
Al
Zn
AsGa
n-G
aA
s
(ba
se
)
p-A
lGa
As
p-G
aA
s
n-G
aIn
P
p-G
aIn
P
p-A
lGaIn
P
p+ G
aA
s
Al
Al Al
P
In
C
ZnSi
Si
Zn
Zn
As
As
In
In
P
Ga
Ga
P
Al
Ga
In
As
P
Zn
C
Si
Concentr
ation o
f ato
ms, cm
-3
Thickness, nm
Al
Si
i-G
aIn
P
n+ GaAs p+ GaAs
C
Demonstration of > 35% efficiency at
500-800 suns in the TJ GaInP/GaAs/Ge
cell with dimensions of 2x2 mm2
Efficiency of the triple-junction
InGaP/InGaAs/Ge solar cell as a function of
temperature at different illumination
conditions (1 sun and 800 suns)
Photoresponse data for triple-junction
GaInP/GaAs/Ge nanoheterostructure
concentrator solar cell with efficiency >36%.
Characteristics of triple-junction GaInP/GaAs/Ge cells
1 10 100 10002,2
2,4
2,6
2,8
3,0
3,2
606468727680848892
Concentration, X
Efficiency
Uх.х.,V
F
F, %
FF
Uх.х.
20
22
24
26
28
30
32
34
36
38
Eff
icie
ncy,%
High temperature stability of concentrator TJ
solar cells.
Temperature coefficient (КТ = 1,5·10-3 ºС-1) of TJ
cell efficiency in three times lower than in silicon
cells.
-50 0 50
30
35
40
45
1 sun
800 suns
Eff
icie
nc
y (η
), %
Cell temperature (T) , ºC
-25 25
KT = 1.5·10-3
ºC-1
400 600 800 1000 1200 1400 1600 18000
20
40
60
80
100
Qu
an
tum
effic
ien
cy, %
Wavelength (), nm
GaInP GaAs Ge
Concentrator modules based on Fresnel lens parquets with
low aperture submodules
A section of a module structure (“all-
glass” design) based on 2 Fresnel lenses
and 2 multijunction solar cells
The tendency in
concentrator PV:
from large to small
concentrators at high
concentration ratio!
Front glass sheet
Fresnel lens profile made of silicone
Solar cell
Bypass diode Copper trough
Upper contact strip
Channel for silica
gel
Rear glass sheet
Advantages of the small-aperture
(16cm2) concentrator sub-modules:
- lower ohmic losses in the small-
area (2-4 mm2) solar cells
- no necessity in compensation of
thermal expansion difference
between materials of a solar cell
and heat sink
- reduced (to 7 cm) thickness of a
module
- lower consumption of the module
housing and heat sink materials.
CPV module (0.5 x 1 m2) based on 288 sub-modules (4cm x 4cm
each) with efficiency exceeding 26% (AM1.5) 7 concentrator modules
(0.5m x 0.5m) based on
144 mini modules each
Rays from Fresnel
lens
Rear glass
sheet
Secondary lens
Solar cell
Heat sink
Design of the submodule with
primary Fresnel lens (is not shown)
and secondary convex lens.
Misorientation angle (± W0.9, curve 1) and maximum local
sunlight concentration (Cmax, curve 2) vs. focal distance of
secondary lenses for PV submodule with 40 x 40 mm2
Fresnel lens and solar cell diameter da = 1.7 mm (without
glass kaleidoscope).
Glass kaleidoscope
Secondary lens
Design of submodule with “short focus” convex
lens and with additional kaleidoscope glued on
the cells surface and providing the uniformity of
the cell illumination
0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,40,6
0,7
0,8
0,9
1,0
Photo
curr
ent,
rel. u
nits
Misorientation angle, degrees
without
secondary
lens
f = 5 mm
f = 11 mm
f = 26 mm
The results on misorientation angle measurements
for a PV sub-module with 40x40 mm2 primary
Fresnel lens, a solar cell 1.7 mm in diameter and
secondary lenses of different focal distances f
(without glass kaleidoscope).
Misorientation characteristics of CPV submodules
0 4 8 12 16 20 24
0
1
2
3
4
5
6
7
8
9
10
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
Maxim
al lo
cal concentr
ation C
ma
x,
10
3suns
Focal distance of secondary lens, mm
1
2
Mis
orie
nta
tio
n a
ng
le,
W 0
.9,a
ng
le
Concentrator PV installations developed at Ioffe Institute
1 kWp
Tower type tracker, front side of array Back side of array
Carousel type tracker, 1 kWp array Concentrator (2 bottom rows) and Si-
type (3 top rows) PV modules, 5 kWp
Advantages of concentrator PV installations based on III-V-heterostructure
solar cells
• Efficiency exceeding 35% in multijunction solar cells at conversion of concentrated sunlight.
• Intermediate concentration (up to 800x) of the sunlight by means of the Fresnel lenses (with optical
efficiency as high as 87%) and proportional decrease in solar cell area and cell specific cost.
• Low temperature coefficient of efficiency: KT = -1/η·dη/dT = 1.5·10-3 ºC-1 – three times less than in the
silicon based modules.
• More than in 2 times increase in electric power amount generated by the concentrator array.
• 1 gram of semiconductor material in a CPV installation provides the same amount of electricity that
provides by 5 tons of petroleum.
• Energy payback time of the developed CPV installations is less than 1 year.
• Decrease in two-three times the quantity of consumable materials (glass sheets, metal components
for modules and trackers, electrical cables and square of land) necessary for CPV installations.
• Predicted specific cost of CPV systems is less than $1.5/Wp at production capacity exceeding
100MWp/year.
10 kW CPV system based on carousel roof-top tracker
design equipped with 30 modules (0.5m x 0.5m each) Scheme of CPV system based on tower-type
tracker with 60 modules (0.5m x 1m each)
Project ROSSOL “Organizing the production of concentrator photovoltaic installations based on nano-heterostructure solar cells”
supported by RUSNANO www.rusnano.com/Post.aspx/Show/24310
• Goal: production of new generation CPV modules with multijunction solar cells,
Fresnel lenses and tracking systems
• Products: Photovoltaic installations with capacity: 3 and 6 kW
• Investment: Total – €125 mln, RUSNANO – €30 mln
• Production volume – 95 MW/year installations
Front surface of solar cells for 1000 suns
CPV module (0.5m x 1m) proposed for production
There is the part of the funds to finance it, and confidence in sales of the
product is very important. Thus we are looking for partners for this project which
has an access to one of the key solar markets.
Concentrator installation
Intellectual property of Ioffe Institute in CPV area
Presence of copyrights:
Priority developments of heterostructure SCs from 1969:
Nobel Prize of Zh. Alferov, technologies, publications, innovation certificates.
Priority developments of concentrator modules based on sun-tracking systems from
1981: publications, technologies, patents.
Priority developments of solar power installations with sun-tracking systems from
1979.
Total number of patents, which are planned to use in the Project, right on which are
possessed by the Ioffe Institute, is 48.
The Ioffe Institute proposes to use 48 know-hows in realizing the Project.
Single-lamp (on the left) and four-lamp (on the right)
flash testers for 3-J solar cells (5000 X)
Testing equipment developed at Photovoltaics laboratory
(http://pvlab.ioffe.ru) of the Ioffe Institute
Colimated light flux
with divergence of 32’
at 1 sun intensity
generated by four
flash lamps.
CPV module aperture
up to 0.5m x 1m
Flash testers were delivered to NREL, Spectrolab (USA), Fraunhofer Institute for Solar Energy
Systems (Germany), SolarTech (Germany), Ricerca Sistema Energetico (Italy), TIPS (China) and
6 Flashers to Russian companies.
Flash tester for MJ solar cells Flash tester for CPV module
Milestones of the future developments
and subjects for cooperation
• Creation of the new generation of CPV installations based on R&D:
- III-V heterostructure solar cells with efficiencies >40% at 1000 suns
- new design and technology of concentrator PV modules with efficiency
~35%
- new design of solar trackers with tracking accuracy of 0.1 angle degree
- new generation of PV systems based on heterostructure solar cells and
concentrators
- monitoring and aging the solar cells, modules, trackers and CPV
systems
• Technologies transfer to partner(s) and organizing the high scale
production of CPV installations with using the developed technologies
- achieving the prognosticated life time >25 year of modules and installations
- providing energy payback time < 1 year
- achieving the cost of CPV system installed power of < €1.5/Wp