Amorphous silicon is a thin film option that has the potential for a cost‐effective product for large‐scale utility photovoltaics application. The initial efficiencies for single‐junction and multijunction amorphous silicon cells and modules have increased significantly over the past 10 years. The emphasis of research and development has changed to stabilized efficiency, especially that of multijunction modules. NREL has measured 6.3%–7.2% stabilized amorphous silicon module efficiencies for U.S. products, and 8.1% stable efficiencies have been reported by Fuji Electric. This represents a significant increase over the stabilized efficiencies of modules manufactured only a few years ago. An increasing portion of the amorphous silicon U.S. government funding is now for manufacturing technology development to reduce cost. The funding for amorphous silicon for photovoltaics by Japan over the last 5 years has been about 50% greater than that in the United States, and by Germany in the last 2–3 years more than twice that of the U.S. Amorphous silicon is the only thin‐film technology that is selling large‐area commercial modules. The cost for amorphous silicon modules is now in the $4.50 range; it is a strong function of plant production capacity and is expected to be reduced to $1.00–1.50/Wpfor plants with 10 MW/year capacities.