.997 Copyright © Gang Chen, MI

or 2.99irect Solar/T

hermal to

2

T

F

7 D

Electrical Energy Conversio

n

Review of Lecture 9

Solar hot water systems Maximum solar concentration Methods for concentration Nontracking and tracking

• Solar thermal-mechanical energy conversion

• EM wave calculation of surface properties

••••

97 Copyrigh

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ergy

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2.9

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For 2.9

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Electrical En

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Review of Lecture 10 By C. Schuh

Image removed due to copyright restrictions.Please see Fig. 3.31 in Porter, David A., andKenneth E. Easterling. Phase Transformations inMetals and Alloys. 2nd ed. New York, NY: Chapman & Hall, 1992.t ©

97 Coht © Gang Chen,

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Review of Lecture 11 By I. Celanovic

Courtesy of Ivan Celanovic. Used with permission.

.997 Copyright © Gang Chen, MI

or 2.99irect Solar/T

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2

T

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Electrical Energy Conversio

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Lecture 12 Solid-State Solar-Thermal Energy Conversion

Solar thermophovoltaics Solar thermophotonics Solar thermoelectrics

•••

pyright © Gang Chen

7 Direct Solar/Therm

ical Energy Conversi

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Electr

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Shockley-Queisser Limit of Solar Cells (Lec.7)

Shockley, W. and Queisser, H.J., Journal of Applied Physics, 32, 510 (1961). Henry, C.H., Journal of Applied Physics, 51, 4494 (1980).

Image removed due to copyright restrictions.Please see Fig. 3 in Henry, C. H. "Limiting Efficiencies of Ideal Single and Multiple Energy Gap Terrestrial Solar Cells."Journal of Applied Physics 51 (August 1980): 4494-4500.

2.997 Copyright © Gang Chen, MIT

For 2.997 Direct Solar/Thermal to

Electrical Energy Conversio

n

Where is energy lost?

k

ENERGY

Eg

k

ENERGY

Eg

hν

Excess Energy

0 0.5 1 1.5 2 2.5 30

200

400

600

800

1000

1200

1400

1600

1800

Terre

stria

l Sol

ar S

pect

rum

(W/m

2 μm

)

AM1.5 Solar Spectrum Energy Usable for Silicon PV Cells

Bandgap of Silicon (1.1 μm)

• Energy below the gap: 20% • Average photon energy

above gap: 1.9 eV • Chemical potential: 0.7 eV

For Eg=1 eV

3.01

7.09.1

18.0 =××= eV

eV

eV

eVη

Wavelength (μm)

Co

2.997 pyrig

ht © Gang Chen, MIT

For 2.997 Direct Solar/Thermal to

Electrical Energy Conversio

n

0 2 4 6 8 10 120

0.5E4

1.0E4

1.5E4

Irradiance From Emitter

0 2 4 6 8 10 120

0.5

1.0

1.5

Selective Emitter 0 5 10 15

0

0.5

1.0

1.5

Selective Absorber

Emitter

TPV Cell

Absorber

Thermal Management

0 0.5 1.0 1.5 2.0 2.5 3.0 0

500

1000

1500 Solar Insolation

Optical Concentrator

Emis

sivi

ty A

bsor

ptan

ce

Wavelength (μm)

Wavelength (μm)

Wavelength (μm)

Pow

er (W

/m2 μ

m)

Pow

er (W

/m2 μ

m)

(a)

(d)

(c)

(b)

Solar Thermophotovoltaics

Fo

yright © Gang Chen, MI

9irect Solar/T

hermal to

2.997 Cop

T

7 D

Electrical Energy Conversio

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Maximum Efficiency of a Solar Thermal Engine (Lec.8)

Jh

Jc

Engine W

Blackbody At Sun’s Temperature Ts

Blackbody Absorber at T

Heat Transferred to Absorber

( )44 TTQ sh −=σ

Thermal Efficiency

( ) 4

4

4

44

1 ss

s th T

T

T

TT −=

− =

σ ση

Carnot Efficiency

T

Ta−=1η

r 2.9Ta

alar/T

he

Conversion

Maximum Efficiency

2.997 Copyright © G

ng Chen, MIT

For 2.997 Direct So

rmal to

Electrical Energy

of a Solar Thermal Engine (Lec.8)

⎟ ⎠ ⎞

T

Ta

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 1000 2000 3000 4000 5000 6000

Series8 E

ffici

ency

Maximum: 85% @ T=2450K For Ta=300 K

⎛ T 4 ⎞ ⎜⎜ ⎟⎟

⎠ η =ηthηC 1−

⎛1−⎜=T 4

s ⎝⎝

Temperature (K)

.997 Copyright © Gang Chen, MI

or 2.99irect Solar/T

hermal to

Problems

2

T

F

7 D

Electrical Energy Conversio

n Needs very narrow bandwidth to achieve Carnot efficiency solar cells. Solar absorption and radiation from absorber does not balance at 2450 K. Difficult to operate at 2450 K.

• Ideal selective surfaces do not exist.

•

•

•

.997 Copt © Gang Chen

For 2.997ct Solar/T

hermal to

Electric

ergy Conversion

– Black Absorber

2

yrigh

, MIT

Dire

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Wuerfel and Ruppel Analysis

Wuerfel and Ruppel, IEEE Trans. Elec. Devices, ED-27, 745, 1980

Images removed due to copyright restrictions.Please see Fig. 1, 3, 4 in Würfel, Peter, and Wolfgang Ruppel."Upper Limit of Thermophotovoltaic Solar-Energy Conversion."IEEE Transactions on Electron Devices ED-27 (April 1980): 745-750.

7 Copyrigh

Gang

7 Dirolar/T

herma

y Conversion

2.

, MIT

or 2.

l to

Wuerfel and Ruppel Analysis – Selective Absorber

h nC

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99

t ©

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Wuerfel and Ruppel, IEEE Trans. Elec. Devices, ED-27, 745, 1980 F

E e t icl c r

Images removed due to copyright restrictions.Please see Fig. 6 and 7 in Würfel, Peter, and Wolfgang Ruppel."Upper Limit of Thermophotovoltaic Solar-Energy Conversion."IEEE Transactions on Electron Devices ED-27 (April 1980): 745-750.

997 Copy

Gang

997

olar/Therma

y Conversion

g t ©

, MIT

or 2

irec

l to

Wuerfel and Ruppel Analysis – Selective Absorber + Filter

h nC

e

ht S

ae g

2.

ri

. DEnl

ic

r

Wuerfel and Ruppel, IEEE Trans. Elec. Devices, ED-27, 745, 1980

FE e tl c r

Images removed due to copyright restrictions.Please see Fig. 9-11 in Würfel, Peter, and Wolfgang Ruppel."Upper Limit of Thermophotovoltaic Solar-Energy Conversion."IEEE Transactions on Electron Devices ED-27 (April 1980): 745-750.

97 Copyright © Gang

97 Direct Solar/Therma

ergy Conversion

, MIT

l to

Optimal Bandgap & Temperature

h nC

e

2 9

E e t icl En.

F l c r aTobias and Luque, IEEE Trans. Electron Dev. 49, 2024 (2002)

r 2 9o

.

Image removed due to copyright restrictions.Please see Fig. 5 in Tobias, I., and A. Luque."Ideal Efficiency and Potential of Solar ThermophotonicConverters Under Optically and Thermally Concentrated Power Flux."IEEE Transactions on Electron Devices 49 (November 2002): 2024-2030.

7 Copyright © Gan

r 2.997 Direct Solar/Ther

lectrical Energy Conversio

n

9

en, MIT

l to

Andreev et al.,

hmg C a

. 92 oF

E Courtesy of Viacheslav Andreev. Used with permission.

97 Copyright ©

C

or 2.997 Direct

hermal

ctrical Ener

versiona

, MI

la

2.9

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Sor/T

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Ele

gy Con

Some Examples

pvlab.ioffe.ru/technology/tpv.html

GaSb Cell

Courtesy of Viacheslav Andreev. Used with permission.

97 Copyright © Gang Che

997 Direct Solar/Thermal to

ergy Conersion

n, MIT

r 2

Solar Thermophotonics

2 9

E e t icl En.

F l c r aTobias and Luque, IEEE Trans. Electron Dev. 49, 2024 (2002)

o.

Image removed due to copyright restrictions.Please see Fig. 1 in Tobias, I., and A. Luque."Ideal Efficiency and Potential of Solar ThermophotonicConverters Under Optically and Thermally Concentrated Power Flux."IEEE Transactions on Electron Devices 49 (November 2002): 2024-2030.

opyright ©

Chen,

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Conversio

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Gang

MIT

For 297 Di

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Electrica

Energy

n

TPH---Monochromatic Limit

LED

cell

T

T−= 1

Copyright © Gang Chen

.997 Direct Solar/Thermal to

ical Energy Conversio

n

2.997

, MIT

or 2

STPH---No Filter

l c rFE e t

Image removed due to copyright restrictions.Please see Fig. 3 in Tobias, I., and A. Luque."Ideal Efficiency and Potential of Solar Thermophotonic Converters Under Optically and Thermally Concentrated Power Flux."IEEE Transactions on Electron Devices 49 (November 2002): 2024-2030.

opyright © Gang Ch

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trical Energy Conversio

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STPH---With Filter

Image removed due to copyright restrictions.Please see Fig. 4 in Tobias, I., and A. Luque."Ideal Efficiency and Potential of Solar ThermophotonicConverters Under Optically and Thermally Concentrated Power Flux."IEEE Transactions on Electron Devices 49 (November 2002): 2024-2030.

.997 Copyrigh

For 2.997 Dir

ectrical

nveang Chen, MI

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2

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Energy Co rsio

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Solar Thermoelectrics

• US Patent No. 389124: E. Weston in 1888

• M. Telkes, JAP, 765, 1954

Efficiency: 0.63%

Image removed due to copyright restrictions.Please see Fig. 6 in Telkes, Maria. "Solar Thermoelectric Generators."Journal of Applied Physics 25 (June 1954): 765-777.

.997 Copyright © G

C

or 2.997 Direct SolThermal

rical Energy

nversion

2

anghen, MIT

F

ar/

to

Elect

Co

Solar Thermoelectrics – Flat Panel Prototypes

Image removed due to copyright restrictions.Please see Fig. 6 in Telkes, Maria. "Solar Thermoelectric Generators."Journal of Applied Physics 25 (June 1954): 765-777.

2.997pyrig

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Dire

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gy C

Solar Thermoelectric Generator ---Concentrated Prototypes

Images and text removed due to copyright restrictions.Please see Fig. 3, 10 and Table III in Dent, C. L., and M. H. Cobble."A Solar Thermoelectric Generator Experiment and Analysis."Proceedings of the International Conference on Thermoelectric EnergyConversion 4 (1982): 75-78.

2.997 Copyright ©

, MI

For 2.997 Direct Solar/

al to

lectrical Energy Co

n

Hybrid PV and TE

Gang Chen T

Therm

E

nversio

Solid-State Solar-Thermal Energy Conversion Center

http://s3tec.mit.edu/

solar spectrum partition device

41 %

Kraemer et al. APL, June 2008

(S3TEC Center)

Gang Chen (Director)

Courtesy of DOE/NREL, Credit - Beck Energy.Courtesy of NASA.

Copyright © Gang Che

2.997 Direct Solar/Thermal t

rical Energy Conversio

n

2. 9

T Two Configurations I, Mn o

9 7

rol cF

E e t Vorobiev et al., J. Solar Energy Eng., 128, 258, 2006.

Image removed due to copyright restrictions.Please see Fig. 1 in Vorobiev, Y. V., et al. "Analysis of Potential Conversion Efficiency of a SolarHybrid System with a High-Temperature Stage." Journal of Solar Energy Engineering 128 (May 2006): 258-260.

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