This paper deals with the computation of power components of distorted signals seen as power quality indices. The proliferation of nonlinear devices into the power system results in nonlinear voltages and currents whereas this unfortunate trend is supposed to increase. The prime tool for spectral analysis is the Discrete Fourier Transform, establishing the preliminary step in the power components computation of distorted signals. Power definitions proposed by Budeanu and afterwards by Shepherd and Zakikhani require spectral components as input. Windowing, leakage and other DFT properties and limitations influence significantly the assessment of power components. The power definition proposed by Skopec and Stec is totally confined to signals represented in time domain. Similar idea was firstly outspoken by Fryze and entirely by-passed the issue of spectral components computation. The authors made an attempt to apply practically different approaches to power components computation for non-sinusoidal currents and voltages.