Thermal characteristics of pressure-driven, power-law fluid flows through narrow confinements are analyzed following a semi-analytical approach, by taking into consideration the electrokinetic effects beyond the Debye-Hückel limit. The influence of the induced streaming potential on the flow velocity, temperature and Nusselt number are delineated for parametric variations of the ionic Peclet number and the flow behaviour index. The effect of viscous dissipation is also incorporated into the thermal analysis. The effects of the streaming potential on the hydrodynamic and thermal characteristics are found to be appreciably different for fluids exhibiting different rheological characteristics.