Thermoelectric materials offer opportunities for the recovery of waste heat into useful electrical energy. As part of a nine member consortium, which included 3 SMEs and 2 large scale enterprises and was supported by the FP7 program, we have investigated the thermoelectric properties of a range of sulphides. This included phases with the tetrahedrite structure, which are promising thermoelectric materials. Our measurements on p-type tetrahedrites indicate that these materials exhibit an unusually low thermal conductivity. In this experiment we seek to exploit neutron diffraction to investigate the mobility of the copper ions within the tetrahedrite structure as a function of temperature, its effect on the thermoelectric properties and impact on long-term stability of these phases.