The dynamical effects on the quantum yield for the electronic state, D(+)MA(-) (the final state) representing the efficiency of the system as an energy conversion system in a model triad system made out of an electron donor, D, an acceptor, A and a medium, M are investigated. The effective quantum yield for the final state is introduced, which is calculated only from the rates in a long time limit, and is applicable even when a memory effect from nuclear dynamics on the rates is considerable. Applying the effective quantum yield formalism, and taking into account multidimensional solvation dynamics by the theory previously developed by the authors, the yield for the final state, is calculated. Considerable dynamical effects are found in some specific situations. For example, the larger yield for the final state is obtained for the larger solvation time scale when the transfer from the initial state, D(*)MA to the final state occurs through the intermediate state, D(+)M(-)A prior to nuclear thermalization in the intermediate state; whereas the similar transfer but with nuclear thermalization in the intermediate state is almost impossible.