We present a numerical study of coherent collisions of multi photovoltaic bright spatial solitons. The result shows that when the colliding solitons are in-phas e, they will attract each other and the inner ones will fuse together gradually. When the relative initial phase between any two adjacent solitons is π2, they will experience a power transfer which includes three basic interaction modes. When the colliding solitons are out of phase, they will propagate stably, which may be useful for the formation of soliton arrays and waveguide arrays.