Mono-crystalline Si solar cells were irradiated by cLINAC with electrons of 8 MeV and Bremsstrahlung photons obtained from electrons of 18 MeV. Systematic dose experiments were conducted with both irradiation types. The current-voltage, capacitance-voltage, conductance-voltage and external quantum efficiency analysis were carried out to investigate the overall effect of radiation on the crystalline Si solar cells. From these measurements, we summarized short-circuit currents, open-circuit voltage, fill factor and efficiency of prepared samples with respect to total applied dose and radiation types. All systematic experiments, measurements and calculations clearly indicate that solar cells are very sensitive to irradiation and nearly all parameters are seem to be decreased with respect to applied dose, regardless of radiation types. Moreover, overall efficiency of the solar cells are degraded by similar to 15 % due to the irradiation which requires more attention for radiation protection of photovoltaic devices in the radiation harsh environments.