Grid-Tied vs Off-Grid Solar: What the DOE Says

A grid-tied solar system stays connected to the utility, while an off-grid system runs on its own with battery storage. The difference shapes whether you need batteries and how you handle excess power. This page sources its facts from the U.S. Department of Energy.

How grid-tied systems handle excess power

The Department of Energy describes net metering as an arrangement between solar energy system owners and utilities in which the system owners are compensated for any solar power generation that is exported to the electricity grid. A grid-tied system can send its surplus back to the utility rather than store it.

Whether that credit applies depends on local rules. The Department of Energy states that whether or not your solar system qualifies for net metering payments depends on policies and practices in your state and electric utility.

Where battery storage comes in

The Department of Energy frames storage as optional for a grid-tied home. It says storage allows you to save that energy and use it later in the day, like when you turn the heat on at night or run the dishwasher after dinner or even when the power goes out.

An off-grid system depends on that storage because it has no utility to fall back on. The Department of Energy notes that batteries allow for the storage of solar photovoltaic energy, so we can use it to power our homes at night or when weather elements keep sunlight from reaching PV panels.

The inverter connects either type to your loads

Both grid-tied and off-grid systems convert direct current to alternating current before powering a home. The Department of Energy explains that inverters are used to convert the direct current electricity generated by solar photovoltaic modules into alternating current electricity.

The department adds that PV systems either have one inverter that converts the electricity generated by all of the modules, or microinverters that are attached to each individual module. That choice applies whether the system stays tied to the grid or runs on its own.