Energy payback assessment framework for distributed PV systems

Solar photovoltaic (PV) generation is recognized as a clean and sustainable energy source, with typical module lifespans exceeding 25 yrs. However, the environmental impacts across the lifecycle of PV systems, including manufacturing, transportation, installation, operation, and decommissioning, can be significant and vary across deployments. Due to the absence of a consistent framework for calculating energy payback time (EPBT), significant variations have been reported in the literature, with reported values ranging from as low as 1.45 yrs to exceeding a decade, which limits the inter-comparability of PV deployments for sustainability assessments. To address these limitations, this paper presents a standardized framework for calculating EPBT, defined as the time required for a PV system to generate the same amount of energy that was used to manufacture, transport, install, operate, and decommission the system. The framework is tested on empirical data from a 42.2 kWp polycrystalline silicon system, along with a comparative analysis to assess how EPBT varies with multiple PV technologies, such as mono-crystalline silicon, copper indium selenide, and cadmium telluride, keeping site location and regional conditions consistent. This work supports PV stakeholders in reducing EPBT through informed technology selection, enabling “greener” PV deployments.