Eﬀect of a hybrid jet impingement/micro-channel cooling device on the performance of densely packed PV cells under high concentration Je ´ro ˆ me Barrau a,⇑ , Joan Rosell a , Daniel Chemisana a , Lounes Tadrist b , M. Iban ˜ez a a Universitat de Lleida, Ediﬁci CREA, C/Pere de Cabrera s/n, Spain b IUSTI, Techn. de Cha ˆteau-Gombert, 5 rue Enrico Fermi, 13453 Marseille, Cedex 3, France Received 18 January 2011; received in revised form 29 July 2011; accepted 5 August 2011 Communicated by: Associate Editor Ruzhu Wang Abstract This paper studies in deep the performance of a new hybrid jet impingement/micro-channel cooling scheme for densely packed PV cells under high concentration. The device combines a slot jet impingement with a non-uniform distribution of micro-channels. The Net PV output of the concentrator system, deﬁned as the PV output less the pumping power, and its temperature uniformity are ana- lyzed. The hybrid cooling scheme oﬀers a minimum thermal resistance coeﬃcient of 2.18  10 5 Km 2 /W with a pressure drop lower than in micro-channel devices. This characteristic involves that the Net PV Output of the PV receiver is higher when cooled by the hybrid design than when cooled by the micro-channel one. The chance to modify, at the design stage, the internal geometry of the hybrid cooling scheme allows improving the temperature uniformity of the PV receiver through the adequate distribution of the local heat removal capacity. Ó 2011 Elsevier Ltd. All rights reserved. Keywords: CPV; Solar concentration; Cooling; Temperature uniformity 1. Introduction As a consequence of the growing eﬃciency of high con- centration PV cells, this technology is seen as one of the ways to reduce the cost of solar electricity. Nowadays, there are modules available in the market with punctual lenses that concentrate the sun on small PV cells. The distance between cells is very large and passive cooling techniques can keep the cells in an optimum operating range of temper- ature. In the case of devices that concentrate the sun, trough mirrors, on densely packed PV cells, it becomes necessary to apply an active cooling on the receiver. On the one hand, for solar concentration ratios above 150 suns, Royne et al. (2005) exposed that the cooling device must have a thermal resistance coeﬃcient lower than 10 4 Km 2 /W. On the other hand, the cooling device must maintain relatively good temperature uniformity. This characteristic aﬀects the global performance of the PV receiver in two ways: (1) Chenlo and Cid (1986) and Royne and Dey (2007) showed that the temperature non-unifor- mity reduced the whole eﬃciency of the PV receiver, although at a lower rate than the non-uniformity of illumi- nation; (2) The lack of uniformity in temperature of the PV cells implies mechanical stress, due to the fact that the ther- mal expansion depends on the local temperature of the receiver. In addition to the large number of thermal cycles that take place in a high concentration PV device, this causes a thermal fatigue of the receiver and aﬀects the reli- ability of the whole system. For solar concentration ratios between 160.8 and 202.9, Zhu et al. (2010) showed that a liquid immersion cooling 0038-092X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.solener.2011.08.004 ⇑ Corresponding author. E-mail addresses: jerome@macs.udl.cat (J. Barrau), rosell@macs.udl. cat (J. Rosell), daniel.chemisana@macs.udl. cat (D. Chemisana), lounes. tadrist@polytech.univ-mrs.fr (L. Tadrist), m.ibanez@macs.udl.cat (M. Iban ˜ ez). www.elsevier.com/locate/solener Available online at www.sciencedirect.com Solar Energy xxx (2011) xxx–xxx Please cite this article in press as: Barrau, J., et al. Eﬀect of a hybrid jet impingement/micro-channel cooling device on the performance of densely packed PV cells under high concentration. Sol. Energy (2011), doi:10.1016/j.solener.2011.08.004