This paper is a study of comparisons between five types of 100 MW Very Large-Scale Photovoltaic Power Generation (VLS-PV) Systems, from economic and environmental viewpoints. The authors designed VLS-PV systems using typical PV modules of multi-crystalline silicon (12·8% efficiency), high efficiency multi-crystalline silicon (15·8%), amorphous silicon (6·9%), cadmium tellurium (9·0%), and copper indium selenium (11·0%), and evaluated them by Life-Cycle Analysis (LCA). Cost, energy requirement, and CO2 emissions were calculated. In addition, the authors evaluated generation cost, energy payback time (EPT), and CO2 emission rates. As a result, it was found that the EPT is 1·5–2·5 years and the CO2 emission rate is 9–16 g-C/kWh. The generation cost was 11–12 US Cent/kWh on using 2 USD/W PV modules, and 19–20 US Cent/kWh on using 4 USD/W PV module price. Copyright © 2007 John Wiley & Sons, Ltd.