Progress in Photovoltaics: Research and Applications

Cover image for Vol. 22 Issue 7

July 2014

Volume 22, Issue 7

Pages 701–850

  1. Accelerated Publication

    1. Top of page
    2. Accelerated Publication
    3. Special Issue Papers
    1. You have free access to this content
      Solar cell efficiency tables (version 44) (pages 701–710)

      Martin A. Green, Keith Emery, Yoshihiro Hishikawa, Wilhelm Warta and Ewan D. Dunlop

      Article first published online: 19 JUN 2014 | DOI: 10.1002/pip.2525

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      Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since January 2014 are reviewed.

  2. Special Issue Papers

    1. Top of page
    2. Accelerated Publication
    3. Special Issue Papers
    1. Boron-doped selective silicon epitaxy: high efficiency and process simplification in interdigitated back contact cells (pages 711–725)

      María Recamán Payo, Niels Posthuma, Angel Urueña de Castro, Maarten Debucquoy and Jef Poortmans

      Article first published online: 9 OCT 2013 | DOI: 10.1002/pip.2427

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      This work proposes the selective epitaxial growth of silicon as an alternative doping technology to boron diffusion. The results presented on the evaluation of boron-doped epitaxial emitters on Czochralski material, their integration in interdigitated back contact cells, and the development of a novel process sequence to create the interdigitated rear junction of these devices using selective epitaxy, demonstrate that boron-doped epitaxy can perform in the high efficiency range (>22%) and that selective epitaxial growth is a feasible approach to simplify the interdigitated back contact solar cells flow.

    2. Towards implementation of floating cast method for growing large-scale high-quality multicrystalline silicon ingot using designed double crucibles (pages 726–732)

      Supawan Joonwichien, Isao Takahashi, Satoru Matsushima and Noritaka Usami

      Article first published online: 7 OCT 2013 | DOI: 10.1002/pip.2428

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      By using double crucibles, the residual melt was spontaneously removed from the inner crucible to the outer one at the final stage of the crystal growth. Performance of small-scale solar cells revealed no significant changes between the top and bottom parts of the ingot except the edge of the bottom due to the nonuniform removal of the melt. This suggests that strong contact of the ingot with the crucible was successfully avoided by the double crucibles.

    3. A case study for micro-grid PV: lessons learned from a rural electrification project in India (pages 733–743)

      Prabakar Loka, Sudir Moola, Karthik Polsani, Shekar Reddy, Shannon Fulton and Andrew Skumanich

      Article first published online: 25 NOV 2013 | DOI: 10.1002/pip.2429

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      Micro-grids in developing countries provide both a major social benefit and also a significant application opportunity for PV as an energy-enabling technology. The authors project 10 GW for this application in the next decade based in part on shared learning of the best practices. Presented are the lessons learned from a successful 1/3 MW rural electrification project in India. The project was done with a goal of optimizing power against cost. Key metrics that quantitatively support the value of PV for rural electrification are developed.

    4. The balance between aesthetics and performance in building-integrated photovoltaics in the tropics (pages 744–756)

      Clarissa Zomer, André Nobre, Pablo Cassatella, Thomas Reindl and Ricardo Rüther

      Article first published online: 31 OCT 2013 | DOI: 10.1002/pip.2430

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      • Even with a theoretically non-optimal combination of azimuthal deviations and tilt angles, System A showed a better performance in yield and performance ratio than Systems B and C, which are installed at more ideal conditions.

      • An optimum string and subsystem configuration can ensure a better performance of photovoltaic (PV) systems under partial shading conditions.

      • In the tropics, rooftop building integrated photovoltaics systems can perform with relatively small losses when compared with optimally tilted and oriented PV generators, while offering high architectural integration appeal.

    5. Temperature-dependent electroluminescence and voltages of multi-junction solar cells (pages 757–763)

      Christian Karcher, Henning Helmers, Michael Schachtner, Frank Dimroth and Andreas W. Bett

      Article first published online: 22 OCT 2013 | DOI: 10.1002/pip.2431

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      We examine the temperature and concentration spectral electroluminescence (EL) of a triple-junction solar cell. By means of the reciprocity relation between EL and external quantum efficiency, we extract the open-circuit voltages of the individual sub-cells and reveal a decreased temperature dependence of the open-circuit voltages with rising bandgap and rising carrier concentration. Finally, we present a way to directly extract the internal cell temperature changes under variation of current density from the EL spectra.

    6. Electrons and holes in solar cells with partial rear contacts (pages 764–774)

      Andres Cuevas

      Article first published online: 22 OCT 2013 | DOI: 10.1002/pip.2433

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      A geometric approach based on partitioning the partial rear contact solar cell in two distinct regions provides physical insight into the transport and recombination of electrons and holes, and permits to optimise the device. The model can be applied to 2D (linear contacts) or 3D (point contacts) designs and to solar cells with or without a locally contacted dopant diffusion on the rear surface.

    7. Development of an IEC test for crystalline silicon modules to qualify their resistance to system voltage stress (pages 775–783)

      Peter Hacke, Ryan Smith, Kent Terwilliger, Greg Perrin, Bill Sekulic and Sarah Kurtz

      Article first published online: 23 NOV 2013 | DOI: 10.1002/pip.2434

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      The damp heat environmental chamber tests run according to the IEC protocol under development distinguish the relative resistance of five module designs to potential-induced degradation in the field and correctly rank order the durability in the field to the extent tested, up to 28 months.

    8. 100-period, 1.23-eV bandgap InGaAs/GaAsP quantum wells for high-efficiency GaAs solar cells: toward current-matched Ge-based tandem cells (pages 784–795)

      Hiromasa Fujii, Kasidit Toprasertpong, Yunpeng Wang, Kentaroh Watanabe, Masakazu Sugiyama and Yoshiaki Nakano

      Article first published online: 23 DEC 2013 | DOI: 10.1002/pip.2454

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      Comprehensive design principle for InGaAs/GaAsP multiple quantum well (MQW) solar cells was proposed, and its effectiveness was experimentally demonstrated. Absolute enhancement of AM 1.5 efficiency with 100-period, 1.23-eV bandgap MQWs was obtained with over 70% internal quantum efficiency as a result of structure optimization. Under AM 1.5 cut-off by a 665-nm long-pass filter, 1.22 times higher efficiency with 38% current enhancement was achieved, indicating a strong potential of the MQW cell introduced into Ge-based 3-J tandem devices.

    9. You have full text access to this OnlineOpen article
      Degradation of interfacial adhesion strength within photovoltaic mini-modules during damp-heat exposure (pages 796–809)

      Dan Wu, Jiang Zhu, Thomas R. Betts and Ralph Gottschalg

      Article first published online: 3 FEB 2014 | DOI: 10.1002/pip.2460

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      Peel tests between the back sheet and encapsulant of commercial mini-modules were conducted at five different damp-heat conditions. A humidity dose model was proposed to describe the cumulative stresses experienced by the module within a certain time period by assuming surface relative humidity of the back sheet as the driving factor for an Arrhenius-based model using temperature as accelerating factor. The adhesion strength demonstrated an exponential decay with humidity dose. This study contributes to the estimation of adhesion reliability in outdoor conditions.

    10. Designing III–V multijunction solar cells on silicon (pages 810–820)

      James P. Connolly, Denis Mencaraglia, Charles Renard and Daniel Bouchier

      Article first published online: 25 JAN 2014 | DOI: 10.1002/pip.2463

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      A novel growth technique for III–V growth on Si for photovoltaic applications allows the design of multijunction solar cells including an active Si substrate. This work analyses multijunction designs specifically for terrestrial applications using ideal limiting efficiency modelling and quantitative, realistic model. A range of available semiconductors is analysed, and realistic record-breaking designs are identified for tandem and triple junction cells in a terrestrial spectrum.

    11. Structural tuning of wide-gap chalcopyrite CuGaSe2 thin films and highly efficient solar cells: differences from narrow-gap Cu(In,Ga)Se2 (pages 821–829)

      Shogo Ishizuka, Akimasa Yamada, Paul J. Fons, Hajime Shibata and Shigeru Niki

      Article first published online: 28 JAN 2014 | DOI: 10.1002/pip.2464

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      Wide-gap chalcopyrite CuGaSe2 (CGS) thin-film solar cells can demonstrate high open circuit voltages (>0.9 V) and high fill factors (>0.7) with high energy conversion efficiencies (>10%) by controlling the Se to Ga flux ratio P[Se]/[Ga] during CGS film growth. Variations in CGS film and device properties observed with various P[Se]/[Ga] are dramatically different from In-containing Cu(In,Ga)Se2.

    12. Combined effect of light harvesting strings, anti-reflective coating, thin glass, and high ultraviolet transmission encapsulant to reduce optical losses in solar modules (pages 830–837)

      Jens Schneider, Marko Turek, Marcel Dyrba, Ihno Baumann, Bernd Koll and Thomas Booz

      Article first published online: 3 FEB 2014 | DOI: 10.1002/pip.2470

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      The individual and combined impact of anti-reflective coatings, thin glass, polyvinyl butyral ultraviolet +, and light harvesting strings on optical properties of solar modules is investigated. Optical measurements are used to calculate the spectral distribution of optical loss mechanisms in solar modules. Solar modules with different configurations are built and measured electrically for comparison. The combined optical improvements lead to 5%rel. increase in photo current and 1% absolute gain in module efficiency.

    13. Value of net-FiT PV policies for different electricity industry participants considering demand-side response (pages 838–850)

      Sebastián Oliva H. and Iain MacGill

      Article first published online: 3 FEB 2014 | DOI: 10.1002/pip.2474

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      We find that under net-metering feed-in-tariffs photovoltaic (PV) policies, demand-side response modestly improves household revenue but has potentially greater implications for retailers and distributors. Household PV customers increasing exports reduce the adverse impacts of PV on retailer and distributors less sales, while increased self-consumption worsens them. Conversely, increased exports might drive distributor expenditures in constrained network residential areas. The study highlights the importance of designing PV policies with regard to their implications for retailers and distribution network service providers as well as PV households.