BOS Costs

In photovoltaic systems, BOS (balance of system) costs include all costs for components and services that are required in order for a photovoltaic plant to be erected and made ready for service - excluding the costs of the modules. These might include, for example, the costs of inverters, substructure, cabling, and connection to the power network. There is however no standard definition of the term 'BOS costs'. Thus in some cases costs for works prior to construction of the PV system, such as restoration work on the roof or the removal of inherited waste, may be included in the figure. Questions of whether work such as construction of the system, the preparation of reports or other services, etc, should be included are not clearly defined and are handled in various ways.

Once it is established which items are included in the BOS costs, these can be used for comparisons between various projects or for a historical overview of cost developments in the photovoltaics sector. For this reason the term BOS is popular with analysts, journalists, and market research institutes.