In this paper, annual average solar radiations satellite datasets for two ground sites in Rwanda and their annual mean sunshine was used to calculate solar insolation of each region.A simplified equivalent circuit model of a silicon photovoltaic cell (PV) of 0.004m2 was modeled and simulated by MAT-LAB/SIMULINK to display PV cell characteristic graphs from which all PV cell describing parameters was calculated.The efficiency obtained shows that for a large amount power generation needs large surface area, since one photovoltaic cell is not practical in application;for practical, paper suggests that photovoltaic cells are connected in a module of series-parallel configuration to produce required output current and voltage.When cells are connected in series with the module, current is the same as PV cell current.In this paper formulas relating cell parameters and solar module was stated.