Validation of a new measuring system for performance evaluation of a large module in a desert area
A. Ghitas1, H. A. Mageed2, Ali El-Rifaie2, V. Schlosser3, M. Sabry1
National Research Institute of Astronomy and Geophysics, Helwan, Cairo, Egypt
National Institute for Standards, Cairo, Egypt
University of Vienna, Faculty of Physics, Vienna, Austria
ABSTRACT: The electrical performance of a module consisting of four identical large area multicrystalline silicon solar cell units connected in series has been studied in a desert area under ambient conditions. Each cell is of area 21cm x 21cm with back contact technology where the current collected by the fine finger grid is led to the back side through 25 holes. On the back side there are 25 soldering pads for each polarity. Short circuit current and open circuit voltage have been measured to describe the module electrical performance. Short circuit current values are obtained by measuring the voltage developed across a known resistance using the current shunt measuring technique to avoid the problems encountered with traditional measuring techniques. Current shunt is not only very stable under a wide range of ambient temperatures but also it has an identical linearity equation, consequently it is safely used in desert areas to obtain the short circuit currents. Furthermore, applying it in the solar cell measuring circuit does not affect the cell temperature dependency due to its negligible temperature coefficient. For outdoor measurements, the module was installed in a tilted position at the optimum angle of the location. The measurements were carried out to assess the parameters and the output performance of this type of solar module. Module performance as a function of incident solar radiation is demonstrated. Moreover, the module overcomes a problem that of the single cell is illustrated.
Keywords: Large Area Multicrystalline Silicon Solar Module, Current Shunt Measuring Technique, Cell and module electrical parameters, Ambient conditions