Extending our previously published model of charge carrier transport and mobility, a procedure for calculation of the semiconductor thermoelectric coefficients is developed. It is shown that the phonon drag strongly influences the Seebeck and Peltier coefficients even at high temperatures, up to 400 K for Si and 600 K for SiC. As a new feature, the presented model gives a possibility to investigate the influence of the electron-hole scattering on thermoelectric coefficients.A strong underestimation of non-isothermal V7-proportional current density terms in most of the semiconductor device simulators is pointed out.