ABSTRACT
This chapter focuses on the design of grid-connected PV systems with battery backup. Battery-backup grid-connected PV system components still must comply with UL 1741. For those who have installed nonbattery-backup systems and then found they would have preferred a battery-backup system, it is possible to add a few extra components, including a battery-backup inverter, batteries, and a standby distribution panel to achieve battery backup. Since most battery-backup systems are designed for use on buildings, new NEC 2014 safety requirements will likely apply to the system design. The important consideration in battery selection is whether to use deep-discharge, flooded lead-acid batteries that will need maintenance and will require special venting or whether to use more-expensive maintenance-free batteries. In battery-backup systems, both the inverter and the charge controller need to be programmed to account for the types of batteries used in the system. The charging process can be achieved with either the inverter, when grid power is available, or the charge controller.
