The effective charge separation has been verified by two LESR signals which were observed only under light excitation. LESR signals can be attributed to positive polarons (P⁺) on the polymer chain with a g-factor g_iso = g_y = 2.0022 and to radical anions of PCBM (P^-) molecules with g_iso = 1.9995. Contrary to the situation in P3AT class polymer with C₆₀ dark signals were absent for both types of radicals. Consequently the fact of the charge separation processes after light excitation of P3DDT/PCBM was clearly detected. Detailed line shape analysis was carried out. Calculated anisotropic g-factors and anisotropic linewidth components for both the Q- and D- bands cases are gathered. Spectrum of polaron was recorded and opposite to the PCBM radical has a very close g-values. Hence it is possible to separate linewidth broadening connected with g-factors anisotropy but one waveband ESR experiment cannot separate the frequency dependent part of ESR linewidth which most probably include the information about the polaron mobility. The effective T₂ without anisotropic broadening was calculated by simulation of experiment and relaxation parameters for both relative P3DDT/PCBM concentrations were calculated. The difference (5-6 times) between T₁ values for P⁺ and P^- radical is in agreement with the results published for analogical composites before.