  We have measured the thermoelectric power of charge density wave system
$o$-TaS$_{3}$ in a wide temperature range between 10 K and 300 K. All features
characteristic for charge density wave systems have been observed; strong
increase below charge density transition temperature $T_{P}$, peak at
$T_{M}\sim$1/2-1/3 $T_{P}$ and change of sign at lower temperatures. These
features can be explained by two contributions; free carriers drag by the
optical phonons with frequencies close to the density wave gap value in the
peak region and above, and hopping of localized carriers of opposite charge to
free carriers at low temperatures. We argue that these are common mechanisms of
thermoelectric power generation in all charge density wave systems.
