These solar PV systems are perfect being used for both cost savings as well as power backup. They work with and interact with the public grid, using grid power when required but also using solar energy to reduce energy costs when available.
A hybrid, grid connected or grid interactive solar PV system reduces your electricity account by allowing you to use solar power during the day. At night the batteries will be discharged to a pre-set depth of discharge, whereby the inverter will automatically switch all the loads back the utility grid.
To be able to have some backup power in case of grid-failures, the depth that the batteries are allowed to discharge determines the quantity and duration of the backup power.
All these settings are fully adjustable. Some inverters will also allow some sort of grid-support for the loads running through the inverters.