Influence of allocation methods on the LC-CO2 emission of an agrivoltaic system

Agrivoltaic systems are multi-output systems where both solar power and crops are produced on the same land. Unlike other land-based photovoltaics (PV), the agrivoltaic PV modules are ground mounted between crops at some height with a certain tilt. Alternatively, PV modules replace part of a greenhouse or are partially set either below or above a covering material. The system could become an important mitigation option for climate change. However, power generation by PV reduces sunlight transmittance and therefore reduces agricultural yield. An allocation method that will address the potential interference of PV with crops is required for life cycle assessment (LCA) to evaluate greenhouse gas mitigation. This study aims to develop a new allocation method (i.e., solar allocation) and compare the LCA results of the new and traditional allocation methods (i.e., system expansion and economic allocation). The partition rate of the solar allocation is derived from the ratio of the active area covered by PV to the greenhouse surface area and light transmittance. These methods were applied to an agrivoltaic tomato production system using protected horticulture with the introduction of organic photovoltaics as a case-study of a system in Japan. The allocation methods considered in the present study could serve as potential methods in assessing life cycle CO2 emissions. Above all, the solar allocation method can be used for many crops that will be influenced by PVs. Further improvement of the allocation method is required in cases where crop growth is less influenced by PVs (e.g., shadow-tolerant crops or transparent PV).