SOLAR CELLS RESEARCH GROUP - RESEARCH
Cell interconnection without glueing or soldering for crystalline Si photovoltaic modules, Johann Summhammer and Zahra Halavani. EPJ Photovoltaics 7, 75401 (2016). http://dx.doi.org/10.1051/epjpv/2016002 (FREE ACCESS)
ABSTRACT: In order to maximize the power output of polycrystalline silicon PV-modules, in previous work we have already tested rectangular cells of 39 × 156 mm which are overlapped along the long sides. The low current density at the cell overlap allows interconnections which need neither soldering nor glueing, but use metallic strips inserted between the cells in the overlap region. The contact is established by the pressure applied to the module during lamination and is retained by the slightly bent cells in the solidified encapsulant. Here we report on the long term stability of different contact materials and contact cross sections applied in eight modules of the 240 W class monitored for up to 24 months of outdoor operation and in a variety of small 5-cell modules exposed to rapid ageing tests with up to 1000 thermal cycles. Cells with three different electrode designs were tested and the contact materials were Cu, Ag, SnPbAg and Sn. Focussing especially on series resistance, fill factor and peak power, it is found that Ag-coated contact strips perform equally well and have practically the same stability as soldered cell interconnections. Due to 70–90% savings in copper and simpler manufacturing the cost of PV-modules may thus be reduced further.
UV-Light-Driven Oxygen Pumping in a High-Temperature Solid Oxide Photoelectrochemical Cell, Georg Christoph Brunauer, Bernhard Rotter, Gregor Walch, Esmaeil Esmaeili, Alexander Karl Opitz, Karl Ponweiser, Johann Summhammer, and Juergen Fleig. Adv. Funct. Mater. 2015, online 19 Nov 2015. DOI: 10.1002/adfm.201503597 ABSTRACT: A solid-state photoelectrochemical cell is operated between 400 and 500 °C under 365 nm UV light. The cell consists of a photovoltaic part, based on a La0.8Sr0.2CrO3/SrTiO3 junction, and an electrochemical part including a zirconia solid electrolyte with a shared (La,Sr)FeO3 electrode. The photovoltaic cell part leads to open circuit voltages up to 920 mV at 400 °C. Upon UV light, this driving force is used in the electrochemical part of the cell to pump oxygen from low to high partial pressures, i.e., to convert radiation energy to chemical energy. This demonstrates the feasibility of high-temperature photo- electrochemical cells for solar energy storage. The detailed characterization of the different resistance contributions in the system by DC and AC methods reveals the parts of the cell to be optimized for finally achieving high-temperature photoelectrochemical water splitting.
Cell interconnection without glueing or soldering for crystalline PV-modules, Johann Summhammer and Zahra Halavani (Talk delivered at Photovoltaic Technical Conference, Aix en Provence, France, 27-29 May, 2015) ABSTRACT: Today's crystalline Si modules from 156 x 156 mm2 cells are „high current – low voltage“ devices with thick internal cabling to get low-resistance cell interconnections. In order to maximize the power output of a module, we identified already earlier the option of rectangular cells (currently 156 x 39 mm) and overlapping them along the long edges. In this work such cells were used in a number of different modules and we focus on the long term stability of the cell interconnections between such cells. These interconnections consist of pure-pressure elements. No soldering and no glueing is used. The contact between the cells is established by two or more contact strips between them in the overlap region so that the cells get slightly bent around them during lamination and the contact force is „frozen in“. This talk presents the latest results of rapid ageing (themal cycling) tests with small modules using different contact materials, as well as the performance of various large modules which have been in outdoor operation for almost two years. PDF (20 slides)
RESULTS OF PRESSURE-ONLY CELL INTERCONNECTIONS IN HIGH VOLTAGE PV-MODULES, Zahra Halavani, Josef L. Lang and Johann Summhammer (Contribution to EUPVSEC, Amsterdam, Sep. 2014) ABSTRACT: PV-modules with small rectangular solar cells from polycrystalline silicon were made in which the cell interconnections consist of overlapping the cells and placing contact strips in between. The lamination pressure bends the cells around the contact strips, which ensures good contact by “pressure-only” after the encapsulating material has hardened. Results are presented of rapid aging tests on small modules and of up to one year of outdoor experience with large modules of the 240 W class. In the latter, all cells are connected in series to obtain operating voltages around 120 V and currents around 2 A. Contact strips with coatings of SnPbAg, Ag, and pure Cu were investigated. The Ag-coated “pressure-only” contact strips performed as well as soldered cell interconnections. Keywords: cell interconnection, silicon solar cell, degradation, module manufacturing, solder free. PDF (5 pages)
High voltage PV-modules with crystalline silicon solar cells, Johann Summhammer and Zahra Halavani (Contribution to EUPVSEC, Paris, Sep. 2013) ABSTRACT: PV-modules in the power range of 220-240 W with over 250 series connected polycrystalline silicon solar cells are introduced, to obtain operating voltages around 120 V. In one type of module standard cells were cut in four to a format of 156 x 39 mm. In another type specially designed QuarterCells were used. For both types specific cell interconnection technology with overlapping cells was developed. It relies on pressure and needs neither soldering nor gluing. Results of repeated temperature cycling of the different connection technologies are presented. Keywords: high voltage, silicon solar cell, module manufacturing, cell interconnection, degradation. PDF (4 pages)
Short flash and constant load PV-module tester, Johann Summhammer (Contribution to IEEE-conference IECON 13, Vienna, Nov.2013) Abstract: A measurement scheme is presented for obtaining the physical parameters of a photovoltaic module with a short light flash. The module is under constant load and voltage and current are recorded during the decaying illumination intensity of the flash. The physical parameters are extracted by means of the one diode model including voltage dependent capacitance. From these parameters the stationary current-voltage curve is reconstructed for a wide range of illumination levels. Keywords—characterization; photovoltaic module; flash test; capacitance; current-voltage curve. PDF (5 pages)
LBIC investigations of multicrystalline silicon solar cells with the front contact on grain boundaries, V. Schlosser, R. Ebner, J. Summhammer, P. Bajons, G. Klinger (Contribution to 20th EUPVSEC, Barcelona, June 2005) ABSTRACT: The spatial variation of locally generated photocurrents has been mapped for multi crystalline silicon solar cells equipped with two different kind of front metal grids. To a portion of the 100 mm × 100 mm solar cells the standard H-pattern with straight metal lines and two busbars was applied. The other cells were equipped with a front grid located on grain boundaries. The light beam induced current (LBIC) set-up works with two fibre coupled luminescence diodes at centre wavelengths of 655 nm and 870 nm respectively. The two light emitting diodes (LEDs) were driven by the same current and individually intensity modulated. A feedback loop for the LED current maintained a constant photocurrent arising from the red LED. The cell current caused by the infrared LED was recorded as a function of the light spot position on the solar cell. The solar cells were investigated under different electrical bias conditions using a low intensity white light background illumination of the whole cell. With the experimental set-up we were able to separate electrical and optical inhomogenities of the surface from the local electrical bulk properties. Keywords: Multi-Crystalline, Silicon, LBIC. PDF (4 pages)
Electrical metastabilities in chalcogenide photovoltaic devices, Sabrina Novalin, Marcus Rennhofer, Johann Summhammer, Thin Solid Films 535 (2013) 261-264. Available online: http://dx.doi.org/10.1016/j.tsf.2012.10.041
Metastabilities in thin-film modules due to pre-treatment, S. Novalin, M. Rennhofer, J. Summhammer, R. Leidl, S. Zamini, Proceedings of 26th European Photovoltaic Solar Energy Conference, Hamburg 5-9 Sep.2011, (WIP-Renewable Energies, Munich 2011; ISBN 3-936338-27-2, www.photovoltaic-conference.com), p.3473-3475. [3 pages]. DOI 10.4229/26thEUPVSEC2011-4AV.1.56
Pre-Treatment Verhalten von Dünnschicht PV-Modulen, S. Novalin, M. Rennhofer, J. Summhammer, R. Leidl, S. Zamini, 26. Symposium Photovoltaische Solarenergie, Tagungsband (2010), S.569-574. Herausgeber: Ostbayerisches Technologie-Transfer-Institut e.V. (OTTI), Regensburg ISBN 978-3-941785-51-9
RECTANGULAR SILICON SOLAR CELL WITH MORE POWER AND HIGHER VOLTAGE MODULES, Johann Summhammer and Harald Rothen, Proceedings of 24th European Photovoltaic Solar Energy Conference, Hamburg, 21-25 Sep. 2009, eds. W.Sinke, H. Ossenbrink and P. Helm, (WIP-Renewable Energies, Munich 2009; ISBN 3-936338-25-6 www.photovoltaic-conference.com), p.2221-2224. [4 pages]
WIRE CELL: A MORE EFFICIENT SILICON SOLAR CELL AND MODULE, Michael Stietka and Johann Summhammer. Proceedings of 23rd European Photovoltaic Solar Energy Conference, Valencia, 1-5 Sep. 2008, eds. D. Lincot, H. Ossenbrink and P. Helm, (WIP-Renewable Energies, Munich 2008; ISBN 3–936338–24-8, www.photovoltaic-conference.com), p.530-533. [4 pages]
Local Characterization Of Multicrystalline Silicon Wafers And Solar Cells, V. Schlosser, M. Dineva, P. Bajons, R. Ebner, J. Summhammer, G. Klinger in “Recent Advances in Multidisciplinary Applied Physics”, Mendez Vilas A. ed., (Elsevier 2005), 415.
LBIC investigations of multicrystalline silicon solar cells with the front contact on grain boundaries.
V. Schlosser, R. Ebner, P. Bajons, J. Summhammer, G. Klinger. Proceedings Photovoltaic Solar Energy Conference, Barcelona, 6-10 June 2005. Eds. W. Palz. H. Ossenbrink and P. Helm, (WIP-Renewable Energies, Munich 2005; www.photovoltaic-conference.com), p.1135-1138. [4 pages]
Metal fingers on grain boundaries in multicrystalline Silicon solar cells. Rita Ebner, Michael Radike, Viktor Schlosser and Johann Summhammer. Prog. Photovolt: Res. Appl. 11, 1-13 (2003). [13 pages]
Investigations of the electro-optical properties of multicrystalline silicon during solar cell processing
V. Schlosser, W. Markowitsch, G. Klinger, P. Bajons, S. Chancy, R. Ebner, J. Summhammer
Contribution to Conference “PV in Europe”, Rome 7-11 Oct. 2002. Proceedings, paper OA1.6. [4 pages]
Galvanic grain boundary contacts on multicrystalline silicon solar cells
Rita Ebner, Maria Raith, Viktor Schlosser and Johann Summhammer
Contribution to Conference “PV in Europe”, Rome 7-11 Oct. 2002. Proceedings, paper OD2.4. [4 pages]
Investigation of evaporated Front Contacts along the grain boundaries of multicrystalline silicon solar cells. V. Schlosser, R. Ebner, W. Markowitsch, P. Bajons, G. Klinger, A.A. El-Amin, J. Summhammer, contribution to 17th European Photovoltaic Solar Energy conference, Munich, Oct. 22-26, 2001, Proceedings, paper VC1.17. [4 pages]. Volume II, p.1470-1473 (WIP, Munich, 2002).
Metal fingers on Grain Boundaries in Multicrystalline Silicon Solar Cells. Rita Ebner, Michael Radike, Viktor Schlosser and Johann Summhammer, contribution to 17th European Photovoltaic Solar Energy conference, Munich, Oct. 2001, Proceedings, paper OC9.1.[4 pages]. Volume I, p.80-83 (WIP, Munich, 2002). (Oral presentation by Rita Ebner.)
Development of Bi-functional Photovoltaic Modules for Building Integration:“BIMODE”, T.M. Bruton, R. Tölle, R. Noble, A. Schneider, J.-P. Janka, H. Costard, J. Claus, M. Radike, J. Summhammer, D. Hillcox, O. Aceves, O. Anzizu, W. Koch, J. Tobias, Luque, GLASGOW, 1-5 May 2000, proceedings.
Performance of single crystal silicon solar cells with decorative busbars. R. Ebner, M. Radike, J. Summhammer, GLASGOW, 1-5 May 2000, proceedings.
Grain boundary oriented finger (GBOF) metalisation on mc silicon solar cells. M. Radike, J. Summhammer, GLASGOW, 1-5 May, 2000, proceedings.
Scanning Kelvin Probe Microscopy for Investigation of Microcrystalline Silicon PIN-Solar Cells. A.Breymesser, V. Schlosser, D. Peiro, C. Voz, J. Bertomeu, J. Andreu, and J. Summhammer, GLASGOW, May 2000, proceedings.
Kelvin Probe Mesurements of Microcrystalline Silicon on a Nanometer Scale using SFM. A.Breymesser, V. Schlosser, D. Peiro, C. Voz, J. Bertomeu, J. Andreu, and J. Summhammer, Solar Energy Materials & Solar Cells 65 (2001) .....
Novel process of grain boundary metallisation on mc Si solar cells. M. Radike, J. Summhammer, Solar Energy Materials & Solar Cells 65 (2001) 303 – 309.
Cross Section Potentiometry of Doped Silicon Structures Using SFM. A. Breymesser, V. Schlosser and J. Summhammer, phys. stat. sol. (b) 215, 855 (1999).
Electrical and Shading Power Losses of Decorative PV Front Contact Patterns. Michael Radike and Johann Summhammer, Prog. Photovolt. Res. Appl. 7, 399-407 (1999).
Optimization of Artistic Contact Patterns on mSi Solar Cells. M. Radike, J. Summhammer, A. Breymesser, V. Sclosser, Proc. 2nd World Conference on Photovoltaic Solar Energhy Conversion, J. Schmid, H.A. Ossenbrink, P. Helm, H. Ehmann, E.D. Dunlop eds. (Luxemburg, Office for Official Publications of the EU, 1998), Report EUR 18656 EN, Vol.II, p. 1603.
A Study of the Charge Transport across Grain Boundaries in Polycrystalline Silicon Solar Cells with a Front Contact along the Grain Boundaries. Viktor Schlosser and Johann Summhammer, Proceedings of the 14th European Photovoltaic Solar Energy Conference, Barcelona, 30 June – 4 July 1997. Eds. H.A. Ossenbrink, P. Helm, H. Ehmann (H.S. Stephens and Associates, Beford, UK) p.716 (1997).
Investigations of a Novel Front Contact Grid on Poly Silicon Solar Cells. J. Summhammer and V. Schlosser, in Proceedings of the "Twelfth European Photovoltaic Solar Energy Conference", eds. R. Hill, W. Palz and P. Helm, (H.S. Stephens & Associates, Bedford, UK, 1994) p.734.