Abstract: Monolithically integrated solar cells produced at high temperatures on high temperature metal substrates are disclosed. The coatings are thin-film and the insulating layer is pinhole and porosity-free. The methods and devices disclosed enable cost-effective, high performing monolithically integrated photovoltaic modules using Copper Indium Gallium di-Selenide (CIGS) films to be made on the dielectric coated metallic substrates. Embodiments of the invention include deposition methods as well as selection of particular insulating materials for deposition on a thermally stable substrate based on the coating's band gap energy, dielectric constant, and coefficient of thermal expansion (CTE). Tandem CIGS solar cells monolithically integrated on flexible substrates may also be produced by the methods and materials disclosed. The tandem solar cell devices include an upper solar cell, a lower solar cell, and an intermediate buffer layer with a tunnel junction.