This section has been divided into three parts. In a stand-alone system, the facility has no connection to the utility grid and often relies on a bank of batteries to store power for use at night and during periods of limited sun. In many utility-interactive systems, surplus electricity from the PV array is exported to the utility grid and bought back when the PV is not producing. In this configuration, the utility grid becomes the storage medium, in place of on-site batteries.
Owners benefit from lower system costs and reduced maintenance.
The utility benefits because the PV system produces its surplus at or near the peak of the utility's demand. Modules, and Arrays Photovoltaic electricity is produced by an array of individual PV modules electrically connected in series and parallel to deliver the desired voltage and current. Modules are connected electrically in series to build voltage while in parallel to build current. The array's operating voltage will determine, or be determined by, the dc input voltage requirement of the inverter and, in stand-alone systems, the battery bank. Balance of Systems Photovoltaic systems require other components in addition to the PV modules.