Structural properties, current-voltage (J-V) characteristics in the dark and under illumination and quantum efficiency are systematically studied and compared for mu c-Si:H solar cells with i-layers deposited by HWCVD or PECVD. A correlation between the increasing V-OC and decreasing crystalline volume fraction of the i-layer can be observed in solar cells deposited by HWCVD and PECVD. At high crystallinity, similar J-V parameters are obtained for both methods. However, HWCVD solar cells can be prepared with lower crystalline volume fractions below 50%, without the drastic drop of solar performance observed in PECVD solar cells. (c) 2005 Elsevier B.V. All rights reserved.