Asymmetrical collisions among three coherent photovoltaic spatial solitons are investigated by numerical method. The numerical results show that the solitons will split or annihilate depending on the incident angle of signal beams in a certain range. If we only change the initial phase difference among the solitons, the collision behavior of solitons will also change correspondingly, showing an interesting conversion of split between annihilation. Furthermore, the numerical results show that the photovoltaic spatial solitons will maintain conservations of momentum and energy in these collision processes, although the dynamical system of photovoltaic solitons is a non-integrable Hamilton one.