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We have studied competitive electron transfers in supramolecular triad systems containing one electron donor and two electron acceptor subunits in polar media. We have chosen two solvent polarization coordinates as reaction coordinates relevant to each electron transfer and introduced two-dimensional free energy surfaces which are functions of the two coordinates. The parameters determining the shape of a free energy surface are the reorganization energies corresponding to each coordinate and the correlation coefficient between the two coordinates. We have calculated these parameters as a function of the geometry of the supramolecule by using the dielectric continuum model and constructed free energy surfaces for a variety of geometries of the supramolecule. By using these surfaces the effect of the geometry of the supramolecule on the competition between the two electron transfers is discussed. The present approach may be used to optimize the geometry of the supramolecule to reduce back electron transfer.