Abstract

In order to achieve competitive system costs in mass-production, it is essential that CPV concentrators incorporate sufficient manufacturing tolerances. This paper presents an advanced concentrator optic comprising a Fresnel lens and a refractive secondary element, both with broken rotational symmetry, an optic producing both the desired light concentration with high tolerance (high acceptance angle) as well as an excellent light homogenization by Köhler integration. This concentrator compares well with conventional Fresnel-based CPV concentrators.

© 2010 OSA

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. P. Benitez, and J. C. Miñano, “Concentrator Optics for the next generation photovoltaics”. Chap. 13 of A. Marti & A. Luque. Next Generation Photovoltaics: High Efficiency through Full Spectrum Utilization, (Taylor & Francis, CRC Press, London, 2004).
  2. A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
    [CrossRef]
  3. S. Kurtz, and M. J. O’Neill, “Estimating and controlling chromatic aberration losses for two-junction, two-terminal devices in refractive concentrator systems”, 25th PVSC; pp.361–367, (1996).
  4. W. Cassarly, “Nonimaging Optics: Concentration and Illumination”, in the Handbook of Optics, 2nd ed., pp. 2.23–2.42, (McGraw-Hill, New York, 2001)
  5. P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
    [CrossRef]
  6. J. C. Miñano, M. Hernandez, P. Benítez, J. Blen, O. Dross, R. Mohedano, and A. Santamaría, “Free-form integrator array optics”, in Nonimaging Optics and Efficient Illumination Systems II, SPIE Proc., R. Winston & T.J. Koshel ed. Vol. 5942–12, (2005).
  7. US and International patents pending by LPI, LLC, 2400 Lincoln Avenue, Altadena, CA 91001 USA http://www.lpi-llc.com/ .
  8. R. Leutz, and A. Suzuki, Nonimaging Fresnel Lenses, (Springer-Verlag, Berlin, 2001).
  9. R. Winston, J. C. Miñano, and P. Benítez, with contributions by N. Shatz and J. C. Bortz, “Nonimaging Optics”, (Elsevier-Academic Press, New York, 2005).
  10. http://www.concentrix-solar.de/fileadmin/user_upload/Download/Technical_Data_Sheets_Q3-2009.pdf .
  11. G. Peharz, J. Jaus, P. Nitz, T. Schmidt, T. Schult, and A. W. Bett, “Development of refractive secondary optics for flatcon® modules”, 23rd European Photovoltaic Solar Energy Conference, 1DV.3.34, (2008). Note that in this reference Cg is defined using a circular active area instead of square, so the geometrical concentration 385x in it corresponds to 302x here.
  12. L. W. James, Contractor Report SAND89–7029, (1989).
  13. D. Anderson, B. Bailor, D. Carroll, E. Schmidt, P. Tyjewski, M. Uroshevich, “Alpha Solarco’s Photovoltaic Development Concentrator Program”, Contractor report SAND95–1557, (1995).
  14. The same BK7 glass has been considered for all the SOE’s under comparison. Though BK7 can be molded (see for instance, http://www.rpoptics.com/index.php?page=rpo-moldable-glass-data ) is more common the use of, for instance, B270. The light absorption in B270 is slightly higher than in BK7, which causes that if the comparison is done using B270, the efficient of the RTP (whose optical path is longer) is penalized the most.
  15. http://www.amonix.com/technology/index.html .
  16. http://www.guascorfoton.com/home_en.php .
  17. See, for instance: www.sol3g.com , http://www.solfocus.com/ , and K. Araki et al., “Development of a new 550X concentrator module with 3J cells-Performance and. Reliability-”, Proc. 31st IEEE PVSC, (2005).
  18. P. Zamora, A. Cvetkovic, M. Buljan, M. Hernández, P. Benítez, J.C. Miñano, O. Dross, R. Alvarez, A. Santamaría, “Advanced PV Concentrators”, 34th IEEE PVSC, (2009).
  19. M. Victoria, C. Domínguez, I. Antón, G. Sala, “Comparative analysis of different secondary optical elements for aspheric primary lenses,” Opt. Express 17, 6487–6492 (2009). The design with highest CAP* in this reference has a rotationally-symmetric CPC-type TIR-based secondary. It achieved CAP* = 0.54 for a square aperture and square cell (for which the FK has a higher value of CAP* = 0.57–0.61). Moreover, it produces a poor irradiance uniformity. It also has the encapsulation problems discussed in Section 5.

2009

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

2004

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Beni´tez, P.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Bett, A. W.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Blen, J.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Braun, A.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Chaves, J.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Dross, O.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Falicoff, W.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Gordon, J. M.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Guter, W.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Hernández, M.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Hirsch, B.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Katz, E. A.

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Miñano, J. C.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Mohedano, R.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Opt. Eng.

P. Benı́tez, J. C. Miñano, J. Blen, R. Mohedano, J. Chaves, O. Dross, M. Hernández, and W. Falicoff, “Simultaneous multiple surface optical design method in three dimensions,” Opt. Eng. 43(7), 1489–1502 (2004).
[CrossRef]

Sol. Energy Mater. Sol. Cells

A. Braun, B. Hirsch, E. A. Katz, J. M. Gordon, W. Guter, and A. W. Bett, “Localized radiation effects on tunnel diode transitions in multi-junction concentrator solar cells,” Sol. Energy Mater. Sol. Cells 93(9), 1692–1695 (2009).
[CrossRef]

Other

S. Kurtz, and M. J. O’Neill, “Estimating and controlling chromatic aberration losses for two-junction, two-terminal devices in refractive concentrator systems”, 25th PVSC; pp.361–367, (1996).

W. Cassarly, “Nonimaging Optics: Concentration and Illumination”, in the Handbook of Optics, 2nd ed., pp. 2.23–2.42, (McGraw-Hill, New York, 2001)

P. Benitez, and J. C. Miñano, “Concentrator Optics for the next generation photovoltaics”. Chap. 13 of A. Marti & A. Luque. Next Generation Photovoltaics: High Efficiency through Full Spectrum Utilization, (Taylor & Francis, CRC Press, London, 2004).

J. C. Miñano, M. Hernandez, P. Benítez, J. Blen, O. Dross, R. Mohedano, and A. Santamaría, “Free-form integrator array optics”, in Nonimaging Optics and Efficient Illumination Systems II, SPIE Proc., R. Winston & T.J. Koshel ed. Vol. 5942–12, (2005).

US and International patents pending by LPI, LLC, 2400 Lincoln Avenue, Altadena, CA 91001 USA http://www.lpi-llc.com/ .

R. Leutz, and A. Suzuki, Nonimaging Fresnel Lenses, (Springer-Verlag, Berlin, 2001).

R. Winston, J. C. Miñano, and P. Benítez, with contributions by N. Shatz and J. C. Bortz, “Nonimaging Optics”, (Elsevier-Academic Press, New York, 2005).

http://www.concentrix-solar.de/fileadmin/user_upload/Download/Technical_Data_Sheets_Q3-2009.pdf .

G. Peharz, J. Jaus, P. Nitz, T. Schmidt, T. Schult, and A. W. Bett, “Development of refractive secondary optics for flatcon® modules”, 23rd European Photovoltaic Solar Energy Conference, 1DV.3.34, (2008). Note that in this reference Cg is defined using a circular active area instead of square, so the geometrical concentration 385x in it corresponds to 302x here.

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

D. Anderson, B. Bailor, D. Carroll, E. Schmidt, P. Tyjewski, M. Uroshevich, “Alpha Solarco’s Photovoltaic Development Concentrator Program”, Contractor report SAND95–1557, (1995).

The same BK7 glass has been considered for all the SOE’s under comparison. Though BK7 can be molded (see for instance, http://www.rpoptics.com/index.php?page=rpo-moldable-glass-data ) is more common the use of, for instance, B270. The light absorption in B270 is slightly higher than in BK7, which causes that if the comparison is done using B270, the efficient of the RTP (whose optical path is longer) is penalized the most.

http://www.amonix.com/technology/index.html .

http://www.guascorfoton.com/home_en.php .

See, for instance: www.sol3g.com , http://www.solfocus.com/ , and K. Araki et al., “Development of a new 550X concentrator module with 3J cells-Performance and. Reliability-”, Proc. 31st IEEE PVSC, (2005).

P. Zamora, A. Cvetkovic, M. Buljan, M. Hernández, P. Benítez, J.C. Miñano, O. Dross, R. Alvarez, A. Santamaría, “Advanced PV Concentrators”, 34th IEEE PVSC, (2009).

M. Victoria, C. Domínguez, I. Antón, G. Sala, “Comparative analysis of different secondary optical elements for aspheric primary lenses,” Opt. Express 17, 6487–6492 (2009). The design with highest CAP* in this reference has a rotationally-symmetric CPC-type TIR-based secondary. It achieved CAP* = 0.54 for a square aperture and square cell (for which the FK has a higher value of CAP* = 0.57–0.61). Moreover, it produces a poor irradiance uniformity. It also has the encapsulation problems discussed in Section 5.

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (16)

Fig. 1
Fig. 1

(Left) 3D view of the LPI’s four-fold Fresnel-Kohler (FK) concentrator: maroon rays show how on-axis rays uniformly illuminate the cell while green rays illustrate how a point of the primary is imaged on the cell, and. (Right) 2D schematic drawing of the edge-ray mapping in an ideal FK concentrator.

Fig. 2
Fig. 2

Phase space representation of the Kohler integration in 2D geometry (the actual design is in 3D) of (a) & (b) the Fresnel Kohler concentrator, (b) & (c) a classical imaging concentrator. The sun is represented by the yellow bar.

Fig. 3
Fig. 3

(Left) Close-up rendering of the center of the LPI’s FK Fresnel lens, showing the four sectors. (Right) Photograph of an LPI’s FK secondary made by glass molding with a ring to be used as holder.

Fig. 4
Fig. 4

(a) Lossless spectral photocurrent densities and spectral optical efficiency of an LPI’s FK concentrator with Cg = 625x and f/1, (b) Monochromatic (at 555 nm) and polychromatic optical efficiencies as a function of the f-number of the FK concentrator, considering no AR coating on the SOE and perfect AR coating (i.e. no Fresnel reflection on the SOE).

Fig. 5
Fig. 5

For an LPI’s FK concentrator with Cg = 625x and f/1: (a) monochromatic (@ 555 nm) power impinging the solar cell as a function of the incidence angle of the parallel rays on the entry aperture, (b) Cell photocurrent as a function of the concentrator tracking error angle for AM1.5d ASMT G173 spectrum (therefore, it accounts for the finite size of the sun and the EQE of the three subcells to find which one is limiting). Both SOE’s, without AR coating and with perfect AR coating, are considered. All curves are relative to normal incidence.

Fig. 6
Fig. 6

Concentration acceptance angle products CAP and CAP* for the LPI’s FK concentrator with no AR coating and with a perfect AR coating on the SOE versus the POE f-number (f/#).

Fig. 7
Fig. 7

Irradiance distribution on the cell for the LPI’s FK concentrator with Cg = 625x, f/1, no AR coating on SOE, when the sun is on axis and the solar spectrum is restricted to: (a) the top-subcell range (360-690 nm), and (b) the middle-subcell range (690-900 nm).

Fig. 8
Fig. 8

Cumulative distribution of light power received on the cell with off–normal angle for the LPI’s FK concentrator with parameters Cg = 625x, f/1, when the sun is perfectly tracked and when the tracking error is 1° (this design has α = ± 1.43 deg).

Fig. 9
Fig. 9

Diagonal cross-section of the Fresnel-based concentrators considered in the comparison. SOE’s and cells are not to scale, but the concentrator depth to POE diagonal ratio is. From left to right: Fresnel (no SOE), Spherical dome, SILO, XTP, RTP, FK concentrator.

Fig. 10
Fig. 10

Cross section of the Secondary Optical Elements of the Fresnel-based concentrators of Fig. 8. All these concentrators have the same POE entry aperture area (625 cm2) and the same acceptance angle (α = ± 1 deg). The cross section of their corresponding cells, which should be centered at the origin, are shown displaced downward to make them visible.

Fig. 11
Fig. 11

Effective concentration acceptance angle product (CAP*) for the concentrators under comparison when the SOE has no AR coating SOE (left) and when a perfect AR coating is assumed (right). The curves of the LPI’s FK concentrator are the same as those shown in Fig. 6.

Fig. 12
Fig. 12

Estimated SOE cost as a function of its height for the RTP SOE and for the Dome-type SOE’s (FK, SILO and spherical dome). The dots correspond to the SOE’s of Fig. 14.

Fig. 13
Fig. 13

SOE and solar cell cost per Fresnel lens unit area as a function of the effective acceptance angle α*. The SOE’s have no AR coating.

Fig. 14
Fig. 14

Cost comparison (per POE unit area) of the set formed by the SOE (green) and solar cell (blue squares) between the RTP and FK with the same POE area (625 cm2) and the same effective acceptance angle α* = ± 1°. The cost advantage of the FK resides on the smaller cell active area needed: 92 mm2 in the RTP versus 59 mm2 in the FK concentrator. The costs of these two SOE’s are highlighted with spots in Fig. 12.

Fig. 15
Fig. 15

Irradiance distributions, in suns (1 sun = 1kW/m2), on the cell for the (a) spherical dome with f/1.5 and the (b) f/1 FK concentrator (this is the average of the graphs in Fig. 7). Both have geometrical Cg = 625x; and α* = ± 0.61° for the spherical dome and α* = ± 1.30° for the LPI’s FK concentrator.

Fig. 16
Fig. 16

Practical aspects of the R-TP secondary versus the LPI’s FK secondary.

Tables (3)

Tables Icon

Table 1 Monochromatic acceptance angle α and effective acceptance angle α* of the LPI’s FK concentrators at different geometrical concentration factors.

Tables Icon

Table 2 Ratio of the distance between the cell and Fresnel lens to the Fresnel lens diagonal (i.e., f-number) of the selected Fresnel-based concentrators under comparison

Tables Icon

Table 3 Geometrical concentration at which the concentrators under comparison are tolerance-equivalent (α* = ± 1°). For this table the f-number of the FK and SILO has been fixed to 1.0 and 1.2, respectively.

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

C A P = C g sin α
η o p t , p o l y c h r o m = I s c c o n c C g I s c 1 s u n = min { I s c , t o p c o n c , I s c , m i d d l e c o n c , I s c , b o t t o m c o n c } C g min { I s c , t o p 1 s u n , I s c , m i d d l e 1 s u n , I s c , b o t t o m 1 s u n }

Metrics