The photoactive material of our solar cells are composites from p-conducting polymer like P3AT and PPV-PPE-copolymers with C60-Buckminsterfullerene. The used polymers were investigated by ESR spectroscopy in the 3-cm and 2-mm (140 GHz) which allows to study the dynamics of the spin charge carriers. Illumination of P3AT-C60 gives also a C60 signal.