The keV-electron irradiation technique is used to study the influence of different spatial distributions of metastable defects on the properties of a-Si:H p-i-n and n-i-p solar cells. The energy dependence of the penetration depth of the keV-electrons is utilized to introduce metastable defects in different regions of the solar cells. A strong influence of the induced defect profiles on the open-circuit voltage and the short-circuit current of the solar cells is found. Internal collection efficiency measurements and modelling show that the relative alteration of the cell parameters contains information about the spatial distribution of the induced metastable defects in the case of standard p-i-n and n-i-p a-Si:H solar cells. On the basis of this result it is concluded that bulk rather than interface degradation is the dominant effect after light soaking and current injection for the solar cells investigated in this study.