The main objective of this study is to determine the real impact of light concentration increase on the parameters of an uncooled PV cell. To obtain results close to the reality, this study takes into consideration the effect of the PV cell heating inherent to light concentration and which is characterized by temperature increase. On the Basis of the thermal model, the temperature profile versus light concentration is determined. And photovoltaic parameters are extracted from the electrical model. Subsequently concentration ratio influence on these photovoltaic parameters is studied. The results indicate that the PV cell’s temperature increases rapidly with light concentration. It appears that diffusion parameters rise when concentration ratio varies from C = 1 Sun where the temperature is T=323.31 K to C = 12.51 Suns where the temperature is T=507.32 K. Beyond C = 12.51 Suns, these diffusion parameters decrease. The results also indicate a strong increase in current density with concentration ratio. This is explained by the fact that concentration ratio and temperature increase are favorable factors for the current. Contrary to many authors, this work shows that the photo-voltage and the conversion efficiency decrease with increasing concentration. This is explained by the antagonism of the effects of concentration and temperature increase on photo-voltage. For concentrations ranging from C = 1 Sun to C = 6 Suns the maximum power increases and decreases beyond C = 6 Suns. For an uncooled silicon PV cell, these results reflect the performance drop with increasing light concentration ratio.