Quick definition
Most solar installations lean on the grid as a fallback: when panels aren't producing enough, the grid fills the gap. An off-grid system doesn't have that option, since there's simply no utility connection to fall back on. Every watt the property uses has to come from the system's own panels, directly or by way of stored battery power, at every hour of every day, year-round.
This fundamentally changes how the system has to be designed, since it needs to handle worst-case conditions on its own rather than averaging out with grid support.
At a glance: off-grid systems are most common on remote properties, cabins, and rural land where running utility lines would be prohibitively expensive or simply isn't available.
Why it matters
Sizing an off-grid system is a fundamentally different exercise than sizing a grid-tied one. A grid-tied system can be sized around typical or average conditions, since the grid smooths out the gaps when production falls short. An off-grid system has to be sized around realistic worst-case conditions, enough panel capacity and enough battery autonomy to survive a genuinely bad stretch of weather without running out of power, since there's no fallback if the estimate runs short. For the numbers behind Off-grid system, the battery storage size calculator in our Battery & Storage section walks through the calculation step by step.
This worst-case design requirement is exactly why off-grid systems tend to cost significantly more per unit of reliable capacity than an equivalent grid-tied system. The battery bank alone often needs to cover several days of full household demand, a very different sizing target than a grid-tied battery that's just smoothing out daily peaks or covering occasional outages.
For most homeowners with existing utility access, going fully off-grid rarely makes financial sense, since the cost of building enough redundancy to match utility-level reliability usually exceeds the cost of simply staying grid-tied. Off-grid genuinely shines specifically where the alternative, running new utility lines to a remote property, is itself extremely expensive or simply unavailable. Extending a utility line even a single mile to a rural parcel can run well into the tens of thousands of dollars once poles, transformers, and labor are factored in, a cost that scales directly with distance from the nearest existing line and can rival or exceed the price of a capable off-grid system outright. The U.S. Energy Information Administration's solar explainer covers off-grid setups, where panels and batteries must cover every load alone.
Where you'll see this
The off grid system autonomy days calculator helps determine how many days of battery backup your specific system needs to realistically survive a poor-weather stretch.
If you're weighing off-grid against extending utility service to a remote property, the off grid system payback vs grid connection tool compares the real costs of both paths.
This term comes up in remote property and cabin planning, in rural land development, and any conversation weighing the cost of full energy independence against the cost of a traditional utility connection. Natural Resources Canada publishes solar photovoltaic information for Canada, including off-grid use in remote communities.
Related terms
Frequently asked
For a property with existing utility access, yes, an off-grid system is generally more expensive upfront, since it needs enough battery capacity and panel capacity to cover every hour on its own. For a remote property where running utility lines would be extremely costly, off-grid can actually work out cheaper than grid connection.
This varies by climate, usage, and risk tolerance, but off-grid systems are commonly designed with several days of autonomy to cover a realistic stretch of poor weather without running out of stored power, since there's no grid fallback if a cloudy period runs longer than expected.
Yes, this describes the vast majority of residential solar installations. A grid-tied system, with or without battery backup, uses the grid as a fallback rather than requiring the system to cover 100% of demand independently, which is a meaningfully different and generally less demanding design goal than going fully off-grid.
Many off-grid systems include a backup generator as insurance against an extended low-sun stretch that exceeds the battery's designed autonomy, since sizing solar and battery capacity for every conceivable worst case would often be prohibitively expensive.