In this paper we present the approach to numerical simulation of the radiation effects in Silicon solar cells with GEANT4 software. Improvements to solar cell radiation hardness are critical for power generation applications in long-term space missions. When solar cells are used in outer space or in Lunar environment, they are subject to bombardment by high-energy particles, which induce a degradation referred to as radiation damage. A family of predictive models for radiation effects induced by high energy protons in a silicon solar cell structure have been developed using a numberof software tools . Simulation of electron radiation effects in solar cells is equally required,but was still missing due the abbsence of the software. GEANT4 is a software toolkit for the simulation of the passage of particles through matter. GEANT4 has both electron and proton radiation simulation capability, that makes it attractive to apply to solar cells simulation. Performed and presented in this paper numerical experiments demonstrate that GEANT4 can be used for simulation of silicon solar cell radiation effects, that was not possible before with other software.