In this work, the importance of the base thickness on the performances of a radial n/p junction solar cell-based polycrystalline silicone is shown. Thus, from a theoretical study under monochromatic illumination in a static regime, we established new analytical expressions of electrical parameters. By simulations on Mathcad 15 software with photocurrent-photovoltage (J/V) and power-photovoltage (P/V) characteristics, we were able to extract the numerical values of maximum power, photovoltage, photocurrent, short-circuit photocurrent, the open-circuit photovoltage, fill factor, optimum load resistance and conversion efficiency (n) for different thicknesses of the base. The analysis clearly shows that unlike the resistance, which decreases, the other parameter values increase with the increase of the base thickness. The short circuit photocurrent density (jphcc) is more sensitive to the thickness H, with an increase of 87% observed. When H increases from 30 to 150 µm, the jphcc goes from 21.989 to 41.161 mA/cm2 . This leads to an improvement in the efficiency Ƞ of the cell, which goes from 9.33% to 21.41% for a thickness of 150µm of the base. Therefore, the optimum thickness for a polycrystalline silicon radial n/p junction solar cell is about 150µm for a wavelength of 1000nm (for Rb=50 µm, Sb =2.102 cm/s, Ln =50 µm, Dn =26 cm2 /s)