The variation of the temperature of the solar cell subjected to the incident global solar radiation along the local daytime in relation to its efficiency is studied. The heat balance equation is solved. The solution revealed that the cell temperature is a function of the maximum value of the daily incident global solar radiation q max , the convection heat transfer coefficient (h), the optical, physical and the geometrical parameters of the cell. The temperature dependence of the short circuit current I sc , the dark saturation current I o , the open circuit voltage V oc , and the energy band gap E g characterizing a Silicon solar cell is considered in evaluating the cell efficiency. Computations of the efficiency concerning operating conditions and astronomical locations (Egypt) as illustrative examples are given.

A general distribution function is suggested to predict both symmetrical and asymmetric diurnal global solar irradiance q (t) W/m 2 received on a horizontal surface, where "t "is the local day time "h".The distribution is given in terms of well-established parameters, namely: td:-the length of the solar day expressed in term of the solar angles.tmax :-the time of the day at which the irradiance reaches its maximum value qmax W/m 2 for symmetrical distribution tmax = 2 i.e., it occurs at the midday time. . are taken as parameters max and q , max , t d t The suggested expression can be easily integrated along the length of the day time. This gives the daily totals of the received solar energy per unit horizontal area. This is of vital technical importance for solar energy exploitations and applications. Comparison between computed according to the present model and published experimental meteorological data in Barcelona (Spain), Hong Kong (China), Jeddah, and Makah (Saudi Arabia) is given as illustrative examples.Comparison with the published trials for the same locations is also clarified. The introduced model itself gives good fitting for the intermediate interval points of the local day time, which is the more effective region.

An analysis is carried out to study the effects of chemical reaction and suction /injection on the flow of a micro polar fluid past a moving plate in the presence of magnetic field and mass transfer. The boundary layer equations are transformed to non-linear ordinary differential equations. Numerical results are presented for the distribution velocity, micro rotation profiles within the boundary layer. The effects of varying magnetic parameter, the non-dimensional chemical reaction parameter , Schmidt number, porosity parameter, micro rotation parameter, and coupling constant parameter are revealed.