Page 10 - RSE - Results of the Apollon Project
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introduction
Concentrating photovoltaics (CPV) can play a key role in the transition towards a sustainable global energy
system, as it offers the possibility to reach high system effciency values and create a low environment impact.
CPV has also great potential for reducing the costs of sun-generated electricity, since it is possible to decrease
the surface covered by expensive solar cells as a function of the concentration factor, by using cheaper optical
elements concentrating the light. At the same time, by reducing the area needed for the semiconductor material,
CPV provides a good answer to the issue of material scarcity. Back in 2007, when the European Commission launched
the call Concentrating photovoltaics: cells, optics, modules under the ENERGY THEME, CPV technology still lacked deep
penetration into the photovoltaic market: the production of CPV system, in fact, lied far back in the 1MW range.
p
Several reasons hindered a large-scale commercialisation of CPV systems, and they were related, mainly, to the
following issues:
1. presence of a large variety of CPV system types;
2. high cost per Watt;
3. poor reliability and lack of international norms and standardisation on CPV;
4. lack of initiatives aimed at supporting the industrial manufacturing of CPV.
1) CPV offered a remarkably large variety of technical possibilities, ranging from low concentration (C<100 suns),
through medium (100
axis trackers, with refective elements (mirrors) or refractive elements (lenses) 1,2,3,4,5,6,7,8 ; such a large variety of
solutions had caused efforts to go off in different technological directions thus hindering their fast development
towards industrial application. There was, however, a clear tendency to focus the attention on high concentration
applications, especially on two groups of systems:
p point focus (PF) systems based on refractive optics;
p point focus or Dense Array (DA) systems based on refective optics.
Both CPV systems had both advantages and disadvantages, so either of them showed its superiority over the
other. For this reason, deepening the knowledge of both technological routes in Europe was important.
Compared to previous European Projects, a novel feature of APOLLON was the possibility to address research
and development activities with a Multi-approach methodology, that is, considering both refractive and refective
CPV systems, thus allowing benchmarking between the different PV technologies, and improving understanding
of the main hurdles to be removed to achieve their successful market penetration.
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1 A.W. Bett at al. “Flatcon and fashcon concepts for high concentration PV”, 19 European Photovoltaic Solar Energy Conference 7-11 June 2004.
2 M. J. O’Neil at al. “Recent Technology Advances for the stretched lens arrays (SLA), a space solar array offering state of the art performance at low cost
and ultra-light mass”, 31 IEEE Photovoltaic Specialist Conference, January 2005.
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3 C. Bingham at al. “Concentrating Photovoltaic module testing at NREL’s Concentrating Solar Radiation Users Facility”. NCPV and Solar Program
Review Meeting 2003.
4 J.L Alvarez at al. “Experimental measurements of RXI concentrators for Photovoltaic application.” 2 World Conference and Exhibition on Photovoltaic
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Solar Energy Conversion 6-10 July, 1998 pp. 2233-2236.
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5 Raed A Sherif at al. “The path to 1GW of Concentrator Photovoltaics Using Multijunction Solar cells”. 31 IEEE Photovoltaic Specialist Conference,
January 2005.
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6 Lewis M. Fraas at al.,“Towards 40% and higher Solar cells in a new Cassegranian PV module”, 31 IEEE Photovoltaic Conference, 2005 Orlando USA.
7 G.Martinelli, “Dichroic Flat faceted concentrator for PV Use”. International Conference on for Solar Concentrators for the Generation of the Electricity
or Hydrogen, May 1-5 2005, Scottsdale, Arizona, USA.
8 M-Alonso Abella at al. “Operation of standard PV modules in v-through concentrators”. 31 IEEE Photovoltaic Specialist Conference, January 2005.
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