High level optical concentration systems can possibly offer a viable alternative to flat panel photovoltaic because large powers can be produced with relatively small amount of photovoltaic cells. At the same time the widespread application of high concentrator systems would not be hindered by the limited amount of silicon available for the flat panel market, since concentration permits the assessment of electronic grade silicon for the cells, and the system production costs would significantly gain from scale law effects. Mirror concentrators, while used nowadays mostly for thermal applications, can be usefully employed for photovoltaic once the peculiar requirements of concentrator systems have been correctly taken into account. Concentration ratios higher than 50X can be attained, for KW’s scale power plants, by the use of composite mirrors array equipped with precise two axis sun tracking systems. A set of flat mirror is mounted on a pseudo-parabolic frame allowing for an highly scalable design. While this ensures a fairly uniform illumination profile, badly needed by photovoltaic receivers, the use of a non-imaging homogenizing concentrator allows for performance and concentration boosting2. Specially designed cells, based on a design similar to the one sun cell, can be employed on concentrator systems with a significant cost reduction3 while the cooling can be based on miniaturized heat exchanger developed on silicon substrates with micromachining techniques5. Moreover the proper selection, by the use of dichroic coatings on the secondary concentrator, of the wavelength reaching the cells allows to significantly improve the cell conversion efficiency and the employable concentration ratios4. The remaining spectrum part can be sent on a separate receiver, like a different cell array of a thermal receiver. We present here an example of a small concentrator system designed and produced along these lines. The system is actually operational at the University of Ferrara and is routinely used for research purposes on the concentration subject.
Composite dish systems for high efficiency concentrator photovoltaics
MALAGU', Cesare;STEFANCICH, Marco;VINCENZI, Donato;PARRETTA, Antonio;
2002
Abstract
High level optical concentration systems can possibly offer a viable alternative to flat panel photovoltaic because large powers can be produced with relatively small amount of photovoltaic cells. At the same time the widespread application of high concentrator systems would not be hindered by the limited amount of silicon available for the flat panel market, since concentration permits the assessment of electronic grade silicon for the cells, and the system production costs would significantly gain from scale law effects. Mirror concentrators, while used nowadays mostly for thermal applications, can be usefully employed for photovoltaic once the peculiar requirements of concentrator systems have been correctly taken into account. Concentration ratios higher than 50X can be attained, for KW’s scale power plants, by the use of composite mirrors array equipped with precise two axis sun tracking systems. A set of flat mirror is mounted on a pseudo-parabolic frame allowing for an highly scalable design. While this ensures a fairly uniform illumination profile, badly needed by photovoltaic receivers, the use of a non-imaging homogenizing concentrator allows for performance and concentration boosting2. Specially designed cells, based on a design similar to the one sun cell, can be employed on concentrator systems with a significant cost reduction3 while the cooling can be based on miniaturized heat exchanger developed on silicon substrates with micromachining techniques5. Moreover the proper selection, by the use of dichroic coatings on the secondary concentrator, of the wavelength reaching the cells allows to significantly improve the cell conversion efficiency and the employable concentration ratios4. The remaining spectrum part can be sent on a separate receiver, like a different cell array of a thermal receiver. We present here an example of a small concentrator system designed and produced along these lines. The system is actually operational at the University of Ferrara and is routinely used for research purposes on the concentration subject.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
