The effects of prolonged exposure to reverse bias DC electric fields and illumination as a function of temperature in hydrogenated amorphous Si (a-Si:H) photovoltaic p-i-n cells have been investigated. These are strongly affected by the well known Staebler-Wronski effect, occurring during light soaking of a-Si:H photovoltaic cells. In this work we show that the application of a reverse bias stress in presence of illumination not only slows down the solar cell ageing kinetics but even produces an improvement of the cells parameters as a function of stress time. We discuss the effect of temperature, electric field intensity and illumination level. We also show that different types of bottom contact over which the a-Si: H is grown by PECVD have a strong influence on the recovery-improvement kinetics: SnO:F (FM) transparent conductive oxide (TCO) and molybdenum bottom contacts to the p-type a-Si:H layer are here compared. Finally, we demonstrate that an analogous improvement (reduction) of sheet resistance is observed in single thin films of doped a-Si:H deposited on SiO2 under the application of high intensity electric fields. (C) 2015 Elsevier B.V. All rights reserved.