1. It describes all components of a photovoltaic system with the exception of photovoltaic modules. These include cabling, switches, a mounting system, one or more solar inverters, batteries and charger.
2. Describes all secondary components for a stable photovoltaic system, apart from the solar modules and the inverters. Among the BoS are mainly the substructure, power cables and other necessary small parts for the installation of a on-roof or open-air solar installation.
https://de.solar-energy.technology/definitionen/balance-of-system.html (1.); https://www.civicsolar.com/support/installer/articles/balance-solar-pv-system-bos (2.)
Author: Frithjof Kühnert