Hybrid, off-grid and grid-tied inverters: which one do you need?
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“Solar inverter” covers three quite different machines. Picking the wrong one is an expensive mistake, because one of them gives no power at all during an outage.
Grid-tied (on-grid) inverters
A grid-tied inverter turns solar power into mains power and feeds it into your home and, if allowed, the grid. It has no battery.
The catch: for the safety of people working on the lines, grid-tied inverters must switch off when the grid goes down. So a home with a grid-tied system usually has no power in a blackout, even on a sunny day.
Good for: cutting electricity bills where the grid is reliable. Not a backup system.
Off-grid inverters (inverter-chargers)
An off-grid inverter runs your home from a battery bank. Most also charge the battery, from solar through a charge controller, from a generator, and often from the grid when it is available. Many can switch to grid power when the battery runs low.
Good for: homes with no grid, or with grid power that is off for long stretches every day. This is the classic “inverter and batteries” setup in many countries with frequent power cuts.
Hybrid inverters
A hybrid inverter combines the two: it handles solar panels, a battery and the grid in one unit, usually with a built-in MPPT charge controller.
- When the grid is up, it can power the home from solar, store surplus in the battery and, where allowed, export to the grid.
- When the grid goes down, it switches to battery and solar, keeping selected circuits or the whole home running.
Good for: most homes that want both backup power and lower bills. This is what most new home systems use.
Which one do you need?
| Your situation | Usual choice |
|---|---|
| Reliable grid, want lower bills only | Grid-tied |
| Frequent outages, want backup and solar | Hybrid |
| No grid, or grid off most of the day | Off-grid inverter-charger, or a hybrid that works off-grid |
| Already have grid-tied solar, want backup | Add a battery system: ask about AC-coupled batteries or replacing with a hybrid |
Questions to ask before buying
- Does it keep the house powered when the grid fails, and how quickly does it switch?
- Which circuits will be backed up: the whole home, or a backup panel?
- Can it charge batteries from a generator, if you have one?
- Is grid export allowed where you live, and does your utility need to approve the system?
- What battery voltage and battery types does it support?
More in 12 questions to ask an installer. To size the inverter, battery and panels, use the calculator.