The soluble fullerene PCBM is an important constituent of organic solar cells acting as an electron capture and transfer agent. We propose to use muon avoided level crossing spectroscopy to establish the properties of muon radicals in this system, which can then be used to probe molecular properties such as the orientational state and in particular electron relaxation processes. A strong sensitivity of the ALC resonances to the PCBM electronic state is expected, for example following electron capture from an exciton in a solar cell to form the negative ion and a singlet state when combined with the electron of the muon radical. This sensitivity will be particularly valuable in future studies of organic photovoltaic materials based on polymer/PCBM composite materials. Future studies plan to use the new laser photoexcitation capability at HiFi to study active organic photovoltaic materials