In order to reduce costs for thin film Si photovoltaic solar, large area VHF plasma CVD technology was developed. Two VHF voltages which had the phase difference controlled by the phase-shifter are supplied to the both ends of an electrode, which is successful in getting time-averaged uniformity of VHF voltage on the electrode. Using the frequency of 60 MHz, the a-Si film with the deposition rate of 1.7 nm/ s +/- 18% was prepared on a 1.4 in x 1.1 m glass substrate. A plasma CVD apparatus with 5 deposition chambers configured in a star shape was fabricated for the production of a-Si solar modules. 728 modules of 1.4 m x 1.1 m were manufactured during the long-run producing test in which deposition and plasma-cleaning were repeated. 93% of total modules manufactured in this test had electric outputs that were included within 2% of the deviation of the average module output. (c) 2005 Published by Elsevier B.V.