ABSTRACT FINAL ID: CONTROL ID: TITLE: … · 2018-02-11 · SOLAR Optics for Solar Energy 11th-14th...

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ABSTRACT FINAL ID: SM2A.3

CONTROL ID: 1464611

TITLE: Free form Optics Applications in Photovoltaic Concentration

Abstract (35 Word Limit): Freeform surfaces are the key of the state-of-the-art nonimaging optics to solvethe challenges in concentration photovoltaics. Different families (FK, XR, FRXI) will be presented, based on theSMS 3D design method and Köhler homogenization.

AUTHORS/INSTITUTIONS: J.C. Minano, , Universidad Politecnica de Madrid, Madrid, SPAIN;

KEYWORDS: General: 000.0000, General: 000.0000.

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SOLAR Optics for Solar Energy 11th-14th November 2012, Eindhoven

1/13

Juan C. Miñano, Pablo Benítez, Pablo Zamora, João Mendes-Lopes, Marina Buljan, Asunción Santamaría

Universidad Politécnica de Madrid (UPM), Spain

LPI , Altadena, California, USA

Freeform Optics Applications in Photovoltaic Concentration

SOLAR Optics for Solar Energy, 11th-14th November 2012, Eindhoven 2/46

Index

1. Introduction

2. Free-forms in asymmetric systems

3. Freeform Köhler array concentrators

The VENTANA optical train

Daido Steel’s DFK

4. Conclusions


PV technologies

Triple-junction III-V cells (C >>1)

III-V cells are very expensive (~$50,000/m2-$150,000/m2)!!!!!

Silicon cells (C = 1)

43.5%


HCPV optical specs

1. Geometrical concentration: 500-1,500

2. Low cost of optics (<$100/m2)

3. High optical efficiency (~80-90%), spectrally balanced

4. Good irradiance uniformity, spectrally balanced

5. High acceptance angle (preferred > ±1deg)


θ (degs)

100

75

50

25

0.5 1 1.5

T(θ) (%)

α

90%

α

Geometrical and chromatic aberrations

Angle at which transmission drops to 90% of maximum

Ideal lens

Real lens

Acceptance angle definition


Tolerance budget has to be shared among:

1. Sun’s angular extension ±0.27° 2. Optical components manufacturing

(shape and roughness) 3. Module assembling 4. Array assembling,

series connection mismatch 5. Tracker structure stiffness 6. Tracking accuracy

Tolerance budget The acceptance angle is a common basis to measure the tolerance of a design


Some Fresnel-based CPV systems


Concentration Acceptance Product

• CAP =

• CAP ≈ constant for a given architecture

• CAP is an important merit function

sinC α×


Classic homogenization scheme

Prism homogenizer

CAP~0.45 CAP~0.18

Refractive Truncated Pyramid (RTP)


Classical mirror based designs

Cell

Parabolic mirror Cassegrian aplanat

CAP~0.49 CAP~0.42


Cassegrian aplanat Parabolic mirror

Some mirror-based CPV systems


Why freeforms in CPV?

• Freeforms provide more freedom to improve performance and functionality

• Nonimaging freeforms are not more expensive than symmetric surfaces

• Symmetric optics cannot solve satisfactorily some asymmetric CPV problems


Index

1. Introduction




Daido Steel’s DFK

4. Conclusions


Solar cell

Homogenizing prism

Free-form primary

mirror (X) Free-form secondary lens (R)

Side view

• Light blocking is avoided • Wide space for heat-sink

The freeform XR concentrator


The SMS3D design method

• SMS3D is an advanced optical design method

• SMS3D is capable to design two freeform surfaces without optimization

• SMS3D deals with extended sources and receivers

Benítez, P., Miñano, J. C., Blen, J., Mohedano, R., Chaves, J., Dross, O., Hernández, M., Falicoff, W, Opt. Eng. 43(7), 1489–1502, (2004)


XR SMS 3D design

A. Cvetkovic et al. Proc. SPIE Vol. 7043-12, 2008

SMS ribs construction


XR SMS 3D design


XR SMS 3D design procedure

Final freeforms


* The XR700 module developed by BOEING Co. and LPI

(A.Plesniak et all. 34th IEEE PV Specialist Conference, 2010)

The freeform XR concentrator

33.2%

Freeform mirror

Freeform lens

A. Cvetkovic, M. Hernández, P. Benítez, J. C. Miñano, J. Schwartz, A. Plesniak, R. Jones, D. Whelan, Proc. SPIE Vol. 7043-12, 2008

C = 1,000x α=±1.8º

Glass cover

CAP~1


Index

1. Introduction




Daido Steel’s DFK

4. Conclusions


The simplest Köhler CPV design

L. W. James, Contractor Report SAND89–7029, (1989)

Images the Fresnel lens on the cell!

2.834511.87419

0.913859-0.0464674

-1.00679-1.967120

0.0000050.00001

0.0000150.00002

0.0000250.00003

0.000035

0.00004

-2.8

3451

-2.2

4593

-1.6

5734

-1.0

6875

-0.4

8016

30.

1084

240.

6970

111.

2856

1.87

419

2.46

277SILO (SIngle Lens secondary Optics)


LPI’s Köhler array concentrators

S

S'

T

T’

O

I

I’

O’ Mi Mo

This can de done in 2D or 3D (free-form surfaces).

The optical process is done in parallel channels that homogenize and concentrate at the same time!


The Fresnel-Köhler (FK) concentrator

P. Benítez, J.C. Miñano, P. Zamora, R. Mohedano, A. Cvetkovic, M. Buljan, J. Chaves, M. Hernández, Optics Express, Vol. 18, Issue S1 (Energy Express), April 2010

Free-form lens


0.0 0.2 0.4 0.6 0.8 1.0

0.59

0.450.36

0.30

0.28

0.18

3

5

7No SOE

Spherical dome

SILO

XTP

RTP

Fresnel Kohler (FK)

No SOE

Spherical dome

SILO

XTP

RTP

Fresnel Kohler (FK)

singCAP C α= ×

25

Comparison

Fresnel-RTP

0 5 10 2015 25-10 -5-15-25 -20

5

10

15

25

20

35

30

40

45

50

(mm)

55

Spherical Dome

FK concentrator

Fresnel-XTP

SILO

Fresnel (no SOE)Since (0.59/0.45)2=1.7, the FK 1,000x is equivalent to an 580x RTP!

APOE=625cm2 α = ±1º


Freeform secondary lens Fresnel lens

The FK concentrator


FK acceptance angle

3.0

3.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

-1.6 -1.2 -0.8 -0.4 0 0.4 0.8 1.2 1.6

Isc (A

)

Tracker angle (º)

Measured = ±1.24o Simulated = ±1.25o

C = 625x


FK irradiance uniformity

-5

5

0

100

200

300

400

500

600

-5

5

-5

5

0

100

200

300

400

500

600

-5

5

Measured Peak irradiance = 595 suns

Simulated Peak irradiance = 575 suns

Suns

Suns


The VentanaTM Optical Train • A complete off-the-shelf optics solution by Evonik and LPI • Based on the best-in-class design: The FK concentrator

POE = primary optical element SOE = secondary optical element

6x6 Fresnel lens parquet

http://corporate.evonik.com/en


0

0.5

1

1.5

2

2.5

3

0 0.5 1 1.5 2 2.5 3

Curr

ent

(A)

Voltage (V)

LPI-Evonik VentanaTM optical train

Pm

Efficiency = 32.8%* Fill Factor = 83.6% Pm = 6.97 W Isc = 2.80 A Voc = 2.95 V Irradiance = 847 W/m2

Entry Aperture = 256 m2

*No AR coatings; @Tcell=25ºC C3MJ Spectrolab cell bin 39%

C = 1,024x α > ±1º


• Daido Steel present CPV system:

• UPM and Daido Steel are developing a new Köhler technology, DFK, within the NGCPV project

*Over illuminated cell area

CAP = Cg x sin α

• Cg* = 950 • α = ±0.92º

CAP = 0.49

• Higher concentration without compromising acceptance angle is desired.

• LPI, in collaboration with UPM, has developed high-performance Köhler freeform concentrators.

DFK


Index

1. Introduction




Daido Steel’s DFK

4. Conclusions


DFK optics • Cg = 1,234 • α > ±1.1º • Module efficiency > 35%

Daedo Steel module

& system technology

LPI Köhler optical

technology

CAP > 0.67

CAP = Cg x sin α

DFK

http://www.daido.co.jp/en/products/cpv/technology.html


POE (4 sectors Fresnel lens)

Flat FK (FK) Dome-shaped FK (DFK)

DFK


17.3

13.8

5.5

5

Cg=1,234x f/ 0.81 SOE material: B270-equiv. glass POE material: PMMA

cell side

design area side

0.25mm wide frame around the cell for assembly tolerances

All dimensions in mm

DFK design parameters


Irradiance uniformity

0

200

400

600

800

1000

1200

1400

suns

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3

Effi

cie

ncy

Angle (deg)

Transmission curve

1.18 deg

90%

AM1.5D spectrum, finite sun, EQE’s of 3J cell, Fresnel and absorption losses included in simulation

CAP=0.72 > 0.67 (spec)

DFK simulation results


AR coating on SOE

Optical efficiency

Acceptance angle

NO 85.6% ±1.18º

YES 87.5% ±1.18º

AR coating

50

55

60

65

70

75

80

85

90

95

100

300 500 700 900 1100 1300 1500 1700

Tran

smis

sion

(%)

Wavelength (nm)

α=0degα=10degα=20degα=30degα=40degα=50degα=60degα=70deg

DFK: AR coating on SOE


ISSUE FLAT FK DOME-SHAPED FK

Acc. angle (α) 1 ±1.03 deg ±1.18 deg

CAP 0.63 0.72

Optical efficiency2 86.5% 87.5%

Irr. uniformity Excellent Very good

F-number 1.07 0.81

1 Cg = 1,234x for both concentrators 2 With AR coating, no rounding of facet corners

Performance comparison


SILO

XTP

RTP

esnel Kohler (FK)

SILO

XTP

RTP

esnel Kohler (FK)

FK

r

r

0.63

DFK 0.72

SILO

XTP RTP

FK DFK

0.28

0.32

0.44

Performance comparison


Practical problems with RTP secondaries

Köhler SOE Classical SOE

Lost ray

Every surface is optically active

Total Internal

Reflection (TIR)

Silicone optical coupler

sealant

Only these surfaces are

optically active

Fixing features


POE mold has a 9-part molding die

3 different demolding movements

Only central part (red) needs positive draft angles

Daedo Steel advanced demolding technique


Index

1. Introduction




Daido Steel’s DFK

4. Conclusions


Conclusions

• Freeform optics is a proven technology for higher performance CPV designs

• Highly asymmetric CPV problems can optimally solved with freeforms, as the SMS3D XR design

• Köhler array concentrators, as the FK, solve practical issues and outperform classical designs

• Further advanced freeform concepts in progress


LEGAL NOTICE

Devices shown in this presentation are protected by the following US and International Patents and Patents Pending:

Patents Issued

HIGH EFFICIENY NON-IMAGING US 6,639,733 October 28, 2003 COMPACT FOLDED-OPTICS ILLUMINATION LENS US 6,896,381 May 24, 2005 COMPACT FOLDED-OPTICS ILLUMINATION LENS US 7,152,985 December 26, 2006 COMPACT FOLDED-OPTICS ILLUMINATION LENS US 7,181,378 February 20, 2007 DEVICE FOR CONCENTRATING OR COLLIMATING RADIANT ENERGY US 7,160,522 January 9, 2007 DISPOSITIVO CON LENTE DISCONTINUA DE REFLEXIÓN TOTAL INTERNA Y DIÓPTRICO ESFÉRICO PARA CONCENTRACIÓN O COLIMACIÓN DE ENERGÍA RADIANTE Spain ES P9902661 December 2, 1999 OPTICAL MANIFOLD FOR LIGHT-EMITTING DIODES US 7,380,962 OPTICAL MANIFOLD FOR LIGHT-EMITTING DIODES US 7,286,296 THREE-DIMENSIONAL SIMULTANEOUS MULTIPLE-SURFACE METHOD AND FREE-FORM ILLUMINATION-OPTICS DESIGNED THEREFROM US 7,460,985 December 2, 2008

Partial List of Patents Pending

DEVICE FOR CONCENTRATING OR COLLIMATING RADIANT ENERGY - a continuation of US 7,160,522 FREE-FORM LENTICULAR OPTICAL ELEMENTS AND THEIR APPLICATION TO CONDENSERS AND HEADLAMPS PCT/US2006/029464 July 28, 2006 MULTI-JUNCTION SOLAR CELLS WITH A HOMOGENIZER SYSTEM AND COUPLED NON-IMAGING LIGHT CONCENTRATOR PCT/US07/63522 March 7, 2007 OPTICAL CONCENTRATOR, ESPECIALLY FOR SOLAR PHOTOVOLTAICS PCT/US08/03439 Mar 14, 2008


• This work is under the NGCPV EU-Japan project, funded by EU Commission (ENERGY,2011,2,1-1 Grant agreement no. 283798) and Japanese NEDO.

• Devices shown in this presentation are protected under US patent 8,000,018 & International patent applications 0905286.3, 200980154626.5, 762MUMNP2011


Thank you!


0.76

0.77

0.78

0.79

0.8

0.81

0.82

0.83

0.84

0.85

0.86

0.87

0.88

0 10 20 30 40 50

Opt

ical

Effic

ienc

y

Edge Radius (μm)

Only Rounded Outer Corners

Equally Rounded Inner and Outer Corners Outer

corners Inner corners

Outer corners

LENS

LENS

No rounded corners

ciency drop due to teeth rounded edges

83.4%

87.5%

30μm

87.0%

0.78

0.79

0.8

0.81

0.82

0.83

0.84

0.85

0.86

0.87

0.88

0.90

0.89

DFK round corners losses


DFK with dimple DFK without dimple


Top view Bottom view

Central dimple enhanced POE design


Index

1. Introduction




Daido Steel’s DFK

4. Conclusions

ABSTRACT FINAL ID: CONTROL ID: TITLE: … · 2018-02-11 · SOLAR Optics for Solar Energy 11th-14th...

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