This study analyzed the profitability and cost constraints of thin film solar PV modules for commercial sized lightweight roofs by using the reversed LCOE method. The focus will be on a particular technology of solar PV, namely, thin film solar PV module technology. Thin film solar PV modules are able to serve the niche market of commercial scale lightweight roofs, without competition with the highly matured traditional solar PV market. As such, the objective of this study is to derive actionable insights into the cost constraints of thin-film solar PV modules for these applications. Using the reversed LCOE method, figures show that there is a high variability in conditions that influences the performance and the profitability of thin film solar PV modules in a commercial scale lightweight roof project. This study shows that both profitable and unprofitable scenarios are possible and provides an analysis on how various conditions influence the project’s profitability.