Quick definition
A grid-tied system stays connected to the utility grid at all times, using that connection as its backup. When panels produce more than the home needs, the surplus flows out to the grid, often earning a bill credit through net metering or a similar program. When panels produce less than the home needs, like at night, the grid supplies the difference.
This is the default configuration for the vast majority of home solar installations, since it avoids the cost and complexity of storing every bit of energy the home might need.
At a glance: grid-tied systems make up the large majority of residential solar installations in the US and Canada, with off-grid systems reserved mostly for remote properties without utility access; SEIA's own installation data puts 97% of all US solar installations on residential rooftops, the vast majority of them grid-connected.
Why it matters
Being grid-tied is what makes solar affordable for most homeowners. An off-grid system has to be sized generously enough, with enough battery capacity, to cover the worst realistic stretch of cloudy weather entirely on its own, since there's no fallback. A grid-tied system doesn't carry that burden. The grid absorbs surplus production and fills in shortfalls, which means the solar array and any optional battery only need to be sized for typical conditions, not worst-case scenarios. For the numbers behind Grid-tied system, the solar panel calculator in our System Sizing section walks through the calculation step by step.
The tradeoff that surprises some new solar owners is what happens during a power outage. Because anti-islanding safety rules require a standard grid-tied inverter to shut off when the grid goes down, even a fully sunny day won't power the house during an outage unless the system includes a battery and compatible hardware specifically designed for backup operation. The system being grid-tied is exactly why it can't simply keep running independently when the grid fails.
This is also why battery retrofits have become common on existing grid-tied systems. A homeowner doesn't have to choose grid-tied versus battery-backed as a permanent, one-time decision. AC coupling in particular makes it straightforward to add battery backup capability to an already-installed grid-tied system without needing to replace the existing solar inverter. The Department of Energy's homeowner guide walks through the main equipment in a grid-tied home solar setup.
Where you'll see this
The grid tie vs off grid comparison tool lays out the real cost and design differences between the two approaches for your specific situation.
If you're weighing whether to add battery backup, the grid tie with battery backup comparison tool shows the added cost and value of pairing a grid-tied system with storage.
This term comes up in nearly every residential solar proposal, in interconnection paperwork, and any time a system's basic architecture, grid-connected versus standalone, needs to be explained, a distinction worth checking against the solar savings calculator by utility rate for the specific financial mechanics that apply to grid-tied systems.
Related terms
Frequently asked
A standard grid-tied system without a battery shuts off during an outage, due to anti-islanding safety requirements, even if the panels are still generating power. Backup power during an outage needs a battery and compatible hybrid inverter added to the system.
Generally yes, often significantly. A grid-tied system doesn't need enough battery capacity to cover every hour of the day, since the grid fills in whenever solar production falls short, while an off-grid system has to be sized to handle worst-case periods entirely on its own.
Yes, this is a common retrofit. Adding a battery, typically through AC coupling to avoid replacing the existing solar inverter, lets a grid-tied system gain backup power capability without switching to a fully off-grid design.
No. Most grid-tied systems installed today don't include a battery, relying on net metering or a similar billing arrangement with the utility instead. A battery adds cost and is typically chosen for backup power value or specific rate structure benefits, not as a requirement for the system to work.