Towards a successful re-use of decommissioned photovoltaic modules

Abstract

Since massive numbers of photovoltaic (PV) modules are expected to be discarded in the next decades, it is important to think about end-of-life management for those PV modules and to include re-use next to recycling. However, the re-use of decommissioned PV modules is a quite complex subject since there are requirements from technical, economic, environmental and legislative point of view. An evaluation of possible applications for second-hand PV modules showed that currently, the use of these PV modules in high-income countries is only interesting for specific applications. These are the replacement of some defect modules to repair PV systems (that usually still receive feed-in tariff) or the replacement of all PV modules for either a low-cost extension of system lifetime or the repowering of severely underperforming systems. For low-income countries, second-hand PV modules are interesting to build new small to medium size PV systems (often off-grid). The typical decommissioned PV module is a crystalline silicon glass-backsheet module from a utility power plant. Most PV modules originate from plants that have been partly damaged by severe weather or from repowered plants that did not receive feed-in tariff (anymore). Currently, technical requirements to qualify potentially re-usable PV modules for re-use are lacking. In the legislation also, a clear criterion for a PV module to be considered functional is needed, since it is not an easy yes/no situation like for a typical electronic device. In this paper, guidelines for a low-cost quality inspection and cost-effective PV module repair are given. It is proposed to set a clear performance threshold at 70% of the original power for a PV module to be not considered as waste. With this paper, we aim to open the dialogue on a commonly accepted re-certification protocol and threshold values. Currently, the worldwide re-use market size is estimated to be around 1 GWp/year, of which 0.3 GWp/year is originating from Europe (mainly Germany, with Italy rapidly coming up). Many second-hand PV modules are shipped to developing countries without recycling facilities which might create the risk of disposal on the longer term. To create a healthy and sustainable market for second-hand PV modules, it will be important that evaluation standards for potentially re-usable PV modules become available and that the existing electronic waste legislation will be adapted for energy-generating products like PV modules.