Abstract

Metal fingers typically cover more than 10% of the active area of concentrator solar cells. Microfabricated dielectric optical designs that can completely eliminate front contact shading losses are explored. Essentially no microconcentrator optical losses need be incurred, series resistance losses can be reduced, and net efficiency gains of roughly 15% (relative) are realistic.

© 2007 Optical Society of America

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References

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  1. G. S. Kinsey, M. Haddad, R. R. King, R. A. Sherif and N. H. Karam, International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, Publ. NREL/CD-520-38172 (National Renewable Energy Laboratory, 2005).
  2. E. A. Katz, J. M. Gordon, W. Tassew, and D. Feuermann, J. Appl. Phys. 100, 044514 (2006).
    [CrossRef]
  3. Z. I. Alferov and V. D. Rumyantsev, in Next Generation Photovoltaics, A.Martí and A.Luque, eds. (Institute of Physics, 2004), Chap. 2.
  4. A. W. Bett, in Next Generation Photovoltaics, A.Martí and A.Luque, eds. (Institute of Physics, 2004), Chap. 4.
  5. M. Yamaguchi, K. Araki, and T. Takamoto, in Concentrator Photovoltaics, A.Luque and V.M.Andreev, eds. (Springer, 2007), Chap. 15.
  6. G. Glenn, Spectrolab Inc., 12500 Gladstone Avenue, Sylmar, Calif., technical prospectus and private communications (2005).
  7. A. Luque, P. Gidon, M. Pirot, I. Antón, C. Del-Cañizo, and C. Jausseaud, Prog. Photovoltaics 12, 517 (2004).
    [CrossRef]
  8. A. Cuevas, R. A. Sinton, N. E. Midkiff, and R. M. Swanson, IEEE Electron Device Lett. 11, 6 (1990).
    [CrossRef]
  9. T. J. Suleski and R. D. TeKolste, J. Lightwave Technol. 23, 633 (2005).
    [CrossRef]
  10. J. Serbin, A. Egbert, A. Ostendorf, B. N. Chichkov, R. Houbertz, G. Domann, J. Schulz, C. Cronauer, L. Frohlich, and M. Popall, Opt. Lett. 28, 301 (2003).
    [CrossRef] [PubMed]
  11. A. Marcinkeviius, S. Juodkazis, M. Watanabe, M. Miwa, S. Matsuo, H. Misawa, and J. Nishii, Opt. Lett. 26, 277 (2001).
    [CrossRef]
  12. Y. Haruvy, I. Gilath, M. Maniewictz, and N. Eisenberg, J. Sol-Gel Sci. Technol. 13, 547 (1998).
    [CrossRef]
  13. R. Winston, J. C. Miñano, and P. Benítez, Nonimaging Optics (Elsevier, 2005).
  14. R. Winston and J. M. Gordon, Opt. Lett. 30, 2617 (2005).
    [CrossRef] [PubMed]
  15. The methods described herein are covered by pending Israeli patent application 181517, "Solar cell optical system," February 22, 2007.

2006 (1)

E. A. Katz, J. M. Gordon, W. Tassew, and D. Feuermann, J. Appl. Phys. 100, 044514 (2006).
[CrossRef]

2005 (2)

2004 (1)

A. Luque, P. Gidon, M. Pirot, I. Antón, C. Del-Cañizo, and C. Jausseaud, Prog. Photovoltaics 12, 517 (2004).
[CrossRef]

2003 (1)

2001 (1)

1998 (1)

Y. Haruvy, I. Gilath, M. Maniewictz, and N. Eisenberg, J. Sol-Gel Sci. Technol. 13, 547 (1998).
[CrossRef]

1990 (1)

A. Cuevas, R. A. Sinton, N. E. Midkiff, and R. M. Swanson, IEEE Electron Device Lett. 11, 6 (1990).
[CrossRef]

IEEE Electron Device Lett. (1)

A. Cuevas, R. A. Sinton, N. E. Midkiff, and R. M. Swanson, IEEE Electron Device Lett. 11, 6 (1990).
[CrossRef]

J. Appl. Phys. (1)

E. A. Katz, J. M. Gordon, W. Tassew, and D. Feuermann, J. Appl. Phys. 100, 044514 (2006).
[CrossRef]

J. Lightwave Technol. (1)

J. Sol-Gel Sci. Technol. (1)

Y. Haruvy, I. Gilath, M. Maniewictz, and N. Eisenberg, J. Sol-Gel Sci. Technol. 13, 547 (1998).
[CrossRef]

Opt. Lett. (3)

Prog. Photovoltaics (1)

A. Luque, P. Gidon, M. Pirot, I. Antón, C. Del-Cañizo, and C. Jausseaud, Prog. Photovoltaics 12, 517 (2004).
[CrossRef]

Other (7)

G. S. Kinsey, M. Haddad, R. R. King, R. A. Sherif and N. H. Karam, International Conference on Solar Concentrators for the Generation of Electricity or Hydrogen, Publ. NREL/CD-520-38172 (National Renewable Energy Laboratory, 2005).

R. Winston, J. C. Miñano, and P. Benítez, Nonimaging Optics (Elsevier, 2005).

The methods described herein are covered by pending Israeli patent application 181517, "Solar cell optical system," February 22, 2007.

Z. I. Alferov and V. D. Rumyantsev, in Next Generation Photovoltaics, A.Martí and A.Luque, eds. (Institute of Physics, 2004), Chap. 2.

A. W. Bett, in Next Generation Photovoltaics, A.Martí and A.Luque, eds. (Institute of Physics, 2004), Chap. 4.

M. Yamaguchi, K. Araki, and T. Takamoto, in Concentrator Photovoltaics, A.Luque and V.M.Andreev, eds. (Springer, 2007), Chap. 15.

G. Glenn, Spectrolab Inc., 12500 Gladstone Avenue, Sylmar, Calif., technical prospectus and private communications (2005).

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Figures (4)

Fig. 1
Fig. 1

Sample commercial triple-junction square concentrator solar cells [2, 3, 6], both with 12% metal grid coverage. (a) 100 mm 2 active area, nominal peak efficiency 31%. (b) 1 mm 2 active area, nominal peak efficiency 39%. (c) Simulation results [2] for contributions to efficiency loss in designing a similar cell tailored so that efficiency peaks at 500 suns (1 sun = 1 mW mm 2 ).

Fig. 2
Fig. 2

Section of the cell’s metal grid (showing current flow in the emitter and grid) [2] and the introduction of a nonimaging ADMC to redistribute impinging light and totally eliminate front contact shadowing losses. In this illustration, the grid spacing remains unchanged. In general, the optic can be adapted to smaller grid spacing, i.e., to a higher coverage fraction, while still totally eliminating grid shading and introducing essentially zero optical loss.

Fig. 3
Fig. 3

θ 1 θ 2 ADMC. Upper contour EDB is the arc of a parabola with focus at A and the axis rotated θ 1 relative to the optic axis. Lower section BA is a straight line tilted at ( θ 2 θ 1 ) 2 . Truncation to point D at angle θ T reduces device depth and concentration (note, however, that rays exit the macroconcentrator and enter the ADMC only at angles θ 1 ). Sufficient truncation yields a pure V-trough. The dielectric region is darkened, and the metal fingers in contact with the cell surface fit comfortably between adjacent troughs. This truncated ADMC has entry D D ( 100 μ m ) , θ 1 = 30 ° , θ 2 = 55 ° , θ T = 46 ° , C = D D A A = 1.50 , and A R = 0.80 .

Fig. 4
Fig. 4

A R as a function of C for ADMCs at prescribed θ 1 and θ 2 = 55 ° . As C is decreased from its maximum [Eq. (1)] by truncation, for each value of θ 1 a point is reached (◆) below which the ADMC is a pure V-trough.

Equations (4)

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C max = sin ( θ 2 ) sin ( θ 1 ) .
θ 1 + θ 2 < 180 ° 2 θ c ,
C = { 2 ( sin ( θ 1 ) + sin ( θ 2 ) ) sin ( θ T ) 1 cos ( θ 1 + θ T ) 1 θ 1 θ T θ 2 sin ( θ T ( θ 1 2 ) + ( θ 2 2 ) ) csc ( θ T + ( θ 1 2 ) ( θ 2 2 ) ) θ 2 θ T 90 ° } ,
A R = { ( sin ( θ 1 ) + sin ( θ 2 ) ) cos ( θ T ) 2 ( sin ( θ 1 ) + sin ( θ 2 ) ) sin ( θ T ) + cos ( θ 1 + θ T ) 1 θ 1 θ T θ 2 csc ( θ T ( θ 1 2 ) + ( θ 2 2 ) ) cos ( ( θ 1 2 ) ( θ 2 2 ) ) cos ( θ T ) θ 2 θ T 90 ° } .

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