Technical note Defects in geometric design of capsulation of commercial poly-Si solar cell module A.H. Hassan National Research Institute of Astronomy and Geophysics, (NRIAG), Helwan, Cairo, Egypt Received 25 March 1999; accepted 26 April 1999 Abstract The shape of capsulation and geometric design play an important role in saving and raising the eciency of the solar cell modules. The measurements of power were carried out for poly-Si solar cell modules in two modes, horizontal and full tracking on the roof top of building in our Institute (NRIAG) in Helwan (Lat. 298 52' N, Long. 318 20' E) which is considered as the largest polluted region in the world. The data measurements are carried out from sunrise to sunset through one full year from January to December 1992. The daily and monthly variation for dierent components of solar cells are studied and discussed. The dierence between the two modes in the gain energy is 84% (about 34% as the natural dierence between the horizontal and full tracking, and 50% by the defect of design of solar cell module). # 1999 Published by Elsevier Science Ltd. All rights reserved. 1. Introduction The performance of solar cell module depends on many parameters. The capsulation and shape of the module is playing a very important role to keep the cells inside the solar cell module and increasing the gain power. The photovoltaic performance depends on the incident radiation and the module or panel tilting angle, beside the solar cell eciency. The percentage of the solar radiation on the surface land is about 80% as the direct solar radiation and about 20% as the diuse solar radiation (as the average on the total clear days) [1]. Many previous 0960-1481/00/$ - see front matter # 1999 Published by Elsevier Science Ltd. All rights reserved. PII: S0960-1481(99)00078-6 Renewable Energy 19 (2000) 617±623 www.elsevier.com/locate/renene E-mail address: amir_hassan@excite.com (A.H. Hassan)