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# Photovoltaic solar energy conversion · PDF file Photovoltaic solar energy conversion. Solar irradiance on earth . Black dot: area of solar panels needed to generate al l of the worlds

Apr 30, 2020

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others

• Albert Polman

FOM Institute AMOLF

Photovoltaic solar energy

conversion

• Solar irradiance on earth

• Black dot:

area of solar panels needed to generate all of the worlds

primary energy (all energy consumed: electricity, heat, fossil

fuels)

assuming 30 % efficient solar panels

∑ = 15 TWe

Solar irradiance on earth

• 20 black dots:

area of solar panels needed to generate all of the worlds

primary energy (all energy consumed: electricity, heat, fossil

fuels)

assuming 30 % efficient solar panels

∑ = 15 TWe

Solar irradiance on earth

• Solar irradiance on earth

1000 black dots:

area of solar panels needed to generate all of the worlds

primary energy (all energy consumed: electricity, heat, fossil

fuels)

Needed: 1) Lower costs

2) Higher efficiency ∑ = 15 TWe

assuming 30 % efficient solar panels

• 400 600 800 1000 1200 1400 1600 18000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wavelength (nm)

Sp ec

tra l i

nt en

si ty

(W /m

2 /n m

)

The solar spectrum

1000 W/m2

Tsun=5800 K

• Solar cell basic design

• 400 600 800 1000 1200 1400 1600 18000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wavelength (nm)

Sp ec

tra l i

nt en

si ty

(W /m

2 /n m

)

The solar spectrum

1000 W/m2

Tsun=5800 K

• 400 600 800 1000 1200 1400 1600 18000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wavelength (nm)

Sp ec

tra l i

nt en

si ty

(W /m

2 /n m

)

Absorption edge and quantum defect

Quantum defect

Absorption above bandgap

Eg

• Voltage is lower than bandgap energy

Iext = I0 exp(V/kT)-ISC

• Voltage is lower than bandgap energy

Iext = I0 exp(V/kT)-ISC

• Voltage is lower than bandgap energy

Iext = I0 exp(V/kT)-ISC

• 400 600 800 1000 1200 1400 1600 18000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wavelength (nm)

Sp ec

tra l i

nt en

si ty

(W /m

2 /n m

) Eg

Voltage is lower than bandgap energy

• 400 600 800 1000 1200 1400 1600 18000

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Wavelength (nm)

Sp ec

tra l i

nt en

si ty

(W /m

2 /n m

)

Voltage is lower than bandgap energy

Eg

Maximum efficiency: 34%

• Shockley-Queisser efficiency limit: 34%

34%

• Silicon is ideal: SQ limit = 33 %

record: 26%

april 1954

• The silicon solar cell turned 60 !

April 25, 1954 Chapin, Fuller en Pearson Bell Telephone Laboratories NJ, USA The first practical solar cell Si: 6 % efficiency

New York Times: the beginning of a new era, leading eventually to the realization of one of mankind’s most cherished dreams – the harnessing of the almost limitless energy of the sun for the uses of civilization

• Vanguard satellite 1958

• 2014

• Periodic Table of solar elements

III-V

II-VI

http://www.pveducation.org/

• http://en.wikipedia.org/

CuInxGa(1-x)Se2 (CIGS) cells: 20.8%

• Absorption length in compound semiconductors

1 µm

Kranz et al., Nature Comm. 4, 2306 (2013) wikipedia.org

• Absorption length in silicon

10 µm

100 µm

physics.ucsd.edu japantechniche.com, pvlab.epfl.edu

• Si solar cell efficiencies

Material Thickness Efficiency Source Monocrystalline Si 260 µm 25.6 % Panasonic (Jap) Polycrystalline Si 99 µm 20.4 % FhG-ISI (Ger) Nanocrystalline Si 2 µm 10.1 % Kaneka (Jap) Amorphous Si 300 nm 10.1 % Oerlikon (Swi)

M.A. Green et al., Prog. Photovolt. Res. Appl. 20, 12 (2011)

ch ea

p ex

p en

si ve

http://www.physics.rutgers.edu/ ~nakhmans/Pro/thesis/node6.html

• Demonstrated solar cell efficiencies

GaInP

• Despite 60 years of research: No material reaches the thermodynamic limit !

GaInP

• Solar power generation system = cells + panel + inverter + system + installation + land

panel € 100 cells € 100

_____ Total € 200

cell eff.=20%

• Solar power generation system = cells + panel + inverter + system + installation + land

panel € 100 + € 100 = € 200 cells € 0 + € 0 = € 0 _____ _____ _____ Total € 100 + € 100 = € 200

cell eff.=10%

cell eff.=10%

• High efficiency is “more important” than low cost

GaInP

• Si bottom cell 1.1 eV

Dual-junction solar cell: thin-film-on-silicon SQ limit: 44%

top cell: 1.8 eV

V V

C C

spectrum splitter

• Dual-junction solar cell: thin-film-on-silicon SQ limit: 44%

Erik Garnett

GaInP

• A. Polman and H.A. Atwater Nature Mater. 11, 174 (2012)

spectrum splitting

Multi-bandgap solar cell designs

series-connected parallel-connected

Efficiency potential > 50%

• Strategies towards high efficiency at low costs

1) Wafer-based Si solar cells (→25-29%) • Reduce costs (=reduce wafer thickness: 10-20 µm) • Decrease recombination at surface, junctions, contacts • Increase light trapping, angular emission restriction,..

2) Thin-film solar cells • Increase efficiency & reduce costs 3) Dual-junction solar cells on silicon (→30-35%) • Increase efficiency and bandgap of top cells • Define spectral splitting architectures 4) New materials and designs (→>40%) • Novel multijunction cell architectures • Nanowire solar cells • ….

• Towards ultra-large-area PV systems worldwide

• Large-scale printing of solar cells

• © Ron Tandberg

Energy from the sun

• © Ron Tandberg

Energy from the sun

is a

science challenge &

technology challenge &

societal/political challenge

• Thank you

www.erbium.nl

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