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Page 1: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

1

Page 2: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Feedstock

Wafer

Cells

Module

Other silicon concepts

Materials availability

2

Page 3: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

3

Page 4: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

Siliconpurification

Crystal

growthWafering Cell

Siemens

process

Multicrystalline

castingWire saw

Screenprint,

BSF, SiN

Semi-grade Si

Union

Carbide, FBR

Multi Si

Bridgeman,

EM casting

Silicon ribbons

EFG, String Ribbon, RGS,

DWeb, RST, SWeb, EZ, SDS, S’tile

Crystalline silicon thin films

Epitaxial growth or multicrystalline growth (annealing,

metal induced, laser induced or zone melting recrystallization)

Solar-grade Si

FBR (HSiCl3 ),

UMGS, VLD

Mono Si

CZ, 3-crystal

Spherical

Sliver

Metallization

Inkjet, PL,

evaporation

Other concepts

HIT, buried or

point contact...

Selectivemitter,

RTP, optical

confinement...

Silicon nanoparticles (Innovalight)

4

Page 5: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Silicon is the second most

abundant element on

Earth after oxygen (28%

of the Earth’s crust). Its

most familiar forms are

sand and quartzite (the

latter one is more pure).

5

Page 6: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Feedstock: obtaining hyperpure silicon from gas

phase

Siemens

process

Fluidized

bed reactor

6

Page 7: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Feedstock: obtaining hyperpure silicon from gas

phase

7

Page 8: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Crystalline silicon may be used in PV in different

forms:

Descriptor Symbol Grain Size

Common

Growth

Techniques

Single crystal sc-Si >10cmCzochralski (CZ)

float zone (FZ)

Multicrystalline mc-Si 1mm-10cm Cast, sheet, ribbon

Polycrystalline pc-Si 1µm-1mmChemical-vapour

deposition

Microcrystalline µc-Si <1µm Plasma deposition

8

Page 9: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Czochralski silicon is the standard for electronics

industry. High quality (mono) with contamination

with oxygen and carbon into the melt.

9

Page 10: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Czochralski silicon

Growth rate: 5cm/hour

10

Page 11: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Float zone silicon is the best

quality silicon

No contamination but very

expensive. Only for very

demanding applications.

11

Page 12: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline silicon offers acceptable quality

but at lower cost

12

Page 13: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline silicon offers acceptable quality

but at lower cost.

Casting or direct solidification, requires careful

thermal control. Crucible usually made of quartz or

graphite, often with Si3N4 coating.

Typical casting:

240kg/56 hours13

Page 14: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline ingots require sawing.

Kerf loss and saw damage removal is significant (and

costly).

14

Page 15: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline wafers may be grown directly in

sheet or ribbon form.

Edge defined film fed growth (EFG)

String ribbon (SR)

Ribbon growth on substrate (RGS)

Dendritic web

Sheet silicon

15

Page 16: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline wafers may be grown directly in

sheet or ribbon form.

Edge defined film fed growth (EFG)

16

Page 17: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline wafers may be grown directly in

sheet or ribbon form.

String ribbon (SR)

17

Page 18: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Multicrystalline wafers may be grown directly in

sheet or ribbon form.

Ribbon growth on substrate (RGS)

18

Page 19: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Main issues to address:

• What to do with edges (~30% volume)

• Higher cost than mcSi due to seeding and slower crystallization

19

Page 20: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

High expectations but markets seems to have given up on quasi-mono…

20

Page 21: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

21

Page 22: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cellsCheck:

PVCDROM

Chapter 6

22

Page 23: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

23

Page 24: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

24

Page 25: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

25

Page 26: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

26

Page 27: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

27

Page 28: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

28

Page 29: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

29

Page 30: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

30

Page 31: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Typical screen printed silicon solar cell manufacturing process

Saw damage etch

Phosphorous diffusion

Edge isolation

Back contact print

Firing

Anti reflective coating

Front contact print

Firing

Testing & sorting

31

Page 32: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Phosphorous diffusion can be inline continuous or batch type

P source: POCl3

32

Page 33: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Screenprinting using silver

paste is standard.

Inkjet alternatives and/or other

materials are fashionable

research topics.

33

Page 34: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Handling thin wafers and

keeping high yields may be

challenging

34

Page 35: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

PV silicon module

Packing density

Interconnection PV cells

Encapsulation

35

Page 36: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

PV silicon module

Packing density

Interconnection PV cells

Encapsulation

36

Page 37: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

PV silicon module

Packing density

Interconnection PV cells

Encapsulation◦ Good transmittance but UV absorbance

◦ Rigidity to withstand mechanical loads

◦ Protection from weather agents and humidity

37

Page 38: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

38

Page 39: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

39

Page 40: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

PERL solar cell

40

Page 41: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Buried contact solar cell

41

Page 42: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Rear interdigitated (RISE) solar cell

42

Page 43: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Rear interdigitated (RISE) solar cell

43

Page 44: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Spheral solar cell

44

Page 45: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Is there a c-Si technology?

Sliver solar cell

45

Page 46: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Silicon solar cells

Materials availability Silicon is very abundant…

Silver paste for the contacts

will be a material bottleneck

Other (temporary)

bottlenecks:

◦ Module glass

◦Tedlar

◦ EVA

Andrea Feltrin, Alex Freundlich, Material considerations for terawatt level deployment of photovoltaics, Renewable Energy 33 (2008) 180–18546

Page 47: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Other materials

47

Page 48: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Other technologies

Other concepts, materials & technologies

◦ a-Si

◦ CIGS

◦ CdTe

It’s not only about efficiency (nor cost!)

48

Page 49: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

49

Page 50: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

Amorphous – commonly applied to

noncrystalline materials prepared by

deposition from gases

First working a-Si based solar cell: Carlson D,

Wronski C, Appl. Phys. Lett. 28, 671 (1976)

Cheaper deposition

Hydrogenated amorphous silicon (a-Si:H)

has higher absorption coefficient than

crystalline silicon – much thinner (<1mm)

solar cells are possible50

Page 51: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

p-i-n configuration

Electron-hole pairs are generated in the

intrinsic ‘thick’ layer and

Separated by the built electric field

Because doped layers have very little diffusion length… 51

Page 52: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

Very thin active layer (<1mm) thus:

requires substrate

Substrate may be glass:

useful for building integrated PV

Substrate may be foil:

useful for flexible solar cells

52

Page 53: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

To increase efficiency, more junctions

(tandem configuration) may be added

A more modern & fashionable second layer: microcrystalline silicon layer 53

Page 54: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

Significant decline in their efficiency during their first few

hundred hours of illumination: Staebler–Wronski effect

54

Page 55: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

PECVD - Plasma enhanced chemical vapour

deposition (a.k.a. RF glow discharge deposition)

SiH4 + H2 into the chamber

RF is applied and generates plasma

plasma excites and decomposes the gas and generates

radicals and ions

that will diffuse onto the

heated substrate

Typical growth speed: 1 angstrom/sec; Typical substrate temperature: 150-350ºC 55

Page 56: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

56

Page 57: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Amorphous silicon solar cells

In summary:

Low efficiency (for the same yield requires more area: module framing & encapsulation become relevant costs)

Low cost (may be interesting if land availability is not an issue)

Niche markets such as building integrated PV, consumer electronics (i.e. gadgets), flexible solar cells,…

57

Page 58: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cadmium Telluride solar cells

CdTe has a high absorption coefficient:

thus very thin active layer

Earliest paper on CdTe solar cell:

Loferski J, J. Appl. Phys. 27, 777–784 (1956)

Most ‘popular’ configuration: CdTe/CdS

heterojunction (p-type CdTe and n-type CdS)

58

Page 59: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

59

Page 60: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cadmium Telluride solar cells

A. Morales-Acevedo, Thin film CdS/CdTe solar cells: Research perspectives, Solar Energy 80 (2006) 675–681 60

Page 61: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cadmium Telluride solar cells

61

Page 62: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cadmium Telluride solar cells

62

Page 63: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cadmium Telluride solar cells

Top efficiencies:

Cell 16.7% (NREL);

Module 10.9% (BP Solarex);

Best seller: First Solar

Main issues:

Cheapest technology

in the market (<1€/Wp)

‘Limited’ efficiency

Reliability (lifetime)

Materials!!

Toxic Cd

Rare Te

Window of

opportunity taken!

63

Page 64: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cu(InGa)Se2 solar cells

Synthesis and characterization were first

reported by Hahn H et al., Z. Anorg. Allg. Chem.

271, 153–170 (1953)

High absorption coefficient: thin film

Like all thin films: potential for cheap

manufacturing for fabrication of monolithically

interconnected modules

Potential for relatively high efficiency: 19.4%

(cell) and 13.5% (module)

64

Page 65: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cu(InGa)Se2 solar cells

P-type: Cu(InGa)Se2

N-type: CdS

65

Page 66: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cu(InGa)Se2 solar cells

66

Page 67: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Cu(InGa)Se2 solar cells

Other different CIGS concepts…

67

Page 68: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Other technologies

Thin silicon

film

CIGS

nanoparticles

Silicon

nanoparticle

ink

DARPA

(spectrum

splitting)

Intermediate

band cells

Dye sensitized

solar cells

Polymer solar

cells

Many other different concepts…

68

Page 69: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Other technologies

69

Page 70: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Comparing different technologies

Cost

Performance/durability

Materials availability

Environmental issues

Maturity

Developers

Market penetration potential & others

70

Page 71: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Energy payback time

V. Fthenakis, E. Alsema, Photovoltaics energy payback times, greenhouse gas emissions and external costs, Prog. Photovolt: Res. Appl. 2006; 14:275–28071

Page 72: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Energy payback time

lifetimelOperationa

timepaybackEnergyyieldEnergy

72

Page 73: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Materials availability

A.Feltrin, A.Freundlich, Material considerations for TW level deployment of PV, Renewable Energy 33 (2008) 180–185

Potential energy limits imposed by global silver (Ag) reserves for bulk-like silicon photovoltaic technologies. The orange

shaded area represents limits reached using 50 mm-thick Ag ribbons. The green shaded area represents limits estimated

using a 2 mm thick Ag electrodes and 5% grid shadowing.

73

Page 74: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Materials availability

A.Feltrin, A.Freundlich, Material considerations for TW level deployment of PV, Renewable Energy 33 (2008) 180–18574

Page 75: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Materials availability

A.Feltrin, A.Freundlich, Material considerations for TW level deployment of PV, Renewable Energy 33 (2008) 180–18575

Page 76: PV TECHNOLOGIES Silicon solar cells - ULisboa...PV TECHNOLOGIES Silicon solar cells Crystalline silicon may be used in PV in different forms: Descriptor Symbol Grain Size Common Growth

PV TECHNOLOGIES

Comparing different technologies

Considering all these factors…

Silicon technologies are to dominate the market in the

foreseeable future

Opportunities for other technologies with industrial

scale, in particular CdTe (e.g. First Solar)

Niche markets are breeding ground for other ‘new’

technologies (thin films in BIPV or flexible applications,

concentration for large solar power plants, etc)

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PV TECHNOLOGIES

Other technologies

Further reading Luque and Hegedus, Handbook of Photovoltaic Science and Engineering. Edited by,John

Wiley & Sons 2003 (Chp 6, 7, 12, 13, 14)

Goetzberger, Photovoltaic Solar Energy Conversion, Springer 2005 (Chp 3)

Sha et al, Thin-film silicon solar cell technology, Prog. Photovolt: Res. Appl. 2004; 12:113–

142 (DOI: 10.1002/pip.533)

Bosio et al, Polycrystalline CdTe thin films for photovoltaic applications, Progress in

Crystal Growth and Characterization of Materials, 52 (2006) 247-279

Morales-Acevedo, Thin film CdS/CdTe solar cells: Research perspectives, Solar Energy 80

(2006) 675–681

Fthenakis, E. Alsema, Photovoltaics energy payback times, greenhouse gas emissions and

external costs, Prog. Photovolt: Res. Appl. 2006; 14:275–280 [Check Fthenakis’s page:

www.bnl.gov/pv

Feltrin, Freundlich, Material considerations for TW level deployment of PV, Renewable

Energy 33 (2008) 180–185

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