It is shown that the degeneracy of the bandstructure has different impacts on thermoelectric properties of III–V materials. A comprehensive list of III–V solid solution alloys that can make multi-valley bandstructures is presented and the transport parameters affecting their thermoelectric power factor are discussed. It is shown that in some cases, such as Ga_xIn_1−xP ternary alloy, the power factor is enhanced significantly near the valley convergence point, but in some other cases, such as Al_xGa_1−xAs, the enhancement is marginal and away from the valley convergence point. Therefore, in addition to the bandstructure engineering, detailed calculation of the transport parameters is also required to determine the optimum alloy composition that can improve the thermoelectric properties.