The aim of this work is to present data concerning the optimization of performances of a large area amorphous silicon p-i-n solar cell (30 x 40 cm(2)) deposited by plasma enhanced chemical vapour deposition (PECVD) at 27.12 MHz. In this work the solar cell was split into small areas of 0.126 cm(2), aiming to study the device performance uniformity, where emphasis was put on the role of the n-layer thickness. The solar cells were studied through the spectral response behaviour in the 400-750 nm range as well as by the behaviour of the AC impedance. Solar cells with fill factor of 0.58, open circuit voltage of 0.83 V, short circuit current density of 17.14 mA/cm(2) and an efficiency of 8% were obtained at growth rates higher than 0.3 nm/s. (c) 2004 Elsevier B.V. All rights reserved.