Heteroepitaxial semiconductor films on low-cost, flexible metal foil templates are a potential route to inexpensive, high-efficiency solar cells. Here, we report epitaxial growth of Si films on low-cost, flexible, biaxially-textured Ni-W substrates. A robust buffer architecture comprised of multiple epitaxial oxide layers has been developed to grow high quality, heteroepitaxial Si films without any undesired reaction between the Si film and the metal substrate and with a single biaxial texture. XRD analysis including ω-scans, φ-scans, and pole figures confirms that the buffers and silicon are all epitaxial, with excellent cube-on-cube epitaxy. A photo-conversion efficiency of 1.1% is demonstrated from a proof-of-concept heteroepitaxial film Si solar cell.