Abstract
Towards a sustainable society, it is necessary to promote high-grade 3Rs of valuable materials for low-carbon technologies. The high-grade 3Rs mean to reduce not the materials themselves but environmental loads in their lifecycle, and to reuse and recycle end-of-use products and scraps from production processes. This paper clarifies requirements to promote high-grade 3Rs of polycrystalline silicon (pc-Si) used for photovoltaic (PV) cells. PV cells with pc-Si are the most popular among all types because of a good balance between their cost and module efficiency. Therefore, we need to ensure pc-Si for PV cells in a sustainable way in response to rapid increase of PV cells. Now that pc-Si for PV cells is produced by an energy-intensive method, reduction of energy in the process is required as well as reduction of pc-Si quantity per watt of produced PV cells. In recycling end-of-use PV modules, quantitative analyses showed that recovered Si should be input after the energy-intensive method to reduce input energy and CO2 emissions. Moreover, assuming that there are no big differences among the total price of PV modules, a liner model with cell price and module efficiency was established. Check with actual data showed that the assessment model can be applied within errors by ±20%. With the assessment model, possibility of reusing and recycling PV modules was explored.
