Solar inverters are not one product with different paint. They are machines with different jobs: follow a grid, form a grid, or do one and then the other after a transfer. The module on the roof does not tell you which inverter you have. The listing does. This page is the map. Comparisons that already exist, central versus string and grid-tied versus off-grid, stay where they are. What follows is how to tell the types apart before you read those articles as if they were the same purchase.
Grid-following solar inverters
A grid-tied inverter synchronizes to the utility and stops when that utility is not a stable reference. IEEE 1547-2018 requires it to cease energizing an unintentional island within 2 seconds, and the type test is done with grid-support functions on. String inverters and central inverters are both usually in this family when they are connected to a utility. The 2017 comparison that still explains the architecture, with capacity bands that are dated and should not be read as a 2026 catalog, is in central versus string solar inverters. Microinverters and power optimizers change where the electronics sit, module by module, which matters most when shade or mixed orientations would otherwise pull a series string down. They do not, by themselves, create backup power. Shade recovery for the module-level products NREL evaluated was about 25 to 35 percent of the shading loss, not a bonus on a clear roof.
The AC voltage still has to be the service. A 220–240 volt single-phase inverter is a product for that service. It is not a 120/240 volt split-phase inverter unless the listing says so. One US utility’s houses are 120/240. Other countries are often near 230 volts. Match the destination. The phase article is single-phase versus three-phase solar inverters.
Grid-forming solar inverters
An off-grid inverter creates the AC waveform from a battery. There is no utility to copy. It will not start because the array is large. It needs a DC source that can supply the load, which is why “solar inverter” on a cabin is a battery inverter plus a way to charge the battery. Sizing that forming inverter for motors and overlapping loads is in how to size an off-grid inverter. Living with the battery is in living off grid with solar storage.
Some off-grid inverters expect a pure sine wave load and some cheaper units produce a stepped approximation. Motors and some chargers care which one they get. The label has to say. That difference is in pure sine wave versus modified sine wave. A grid-tied inverter is already producing a waveform acceptable to the utility. You do not swap in a modified-sine unit and call it grid-tied.
Solar inverters that can do both
A hybrid is the marketing word for an inverter that can follow the grid and also charge or discharge a battery. It can support backup only if it disconnects from the utility before it forms an island, and only for the circuits that were transferred. Buying the word hybrid without the circuit list is how a grid-tied system is sold as backup. The system-level split is in grid-tied versus off-grid solar. Adding a battery later, to an inverter that cannot take one, is a different project: adding a battery to existing solar.
| Type | What it must be able to do |
|---|---|
| Grid-tied string, central, or micro | Follow the utility. Stop within 2 seconds if the grid islands. No backup unless other equipment was added. |
| Off-grid | Form the AC supply from a battery. Size for surge and continuous load. Will not run a house from modules alone. |
| Hybrid | Follow the grid when connected. Form an island only after disconnection, and only if that mode is actually built and listed. |
Efficiency, warranty years, and transformer versus transformerless construction are datasheet lines, not types. PNNL notes that large central inverters often include a transformer and that smaller central inverters and microinverters are typically transformerless. That changes grounding and, on floating-ground designs, what you must check for potential-induced degradation on the module. It does not change the table above. Peak efficiency is one operating point. Do not rank types by a single percentage from a brochure.
A charge controller is not a fifth type of solar inverter. It regulates current into a battery. It does not make the AC waveform the building uses. A cabin can have both: a controller on the array and an inverter on the battery. Calling the controller an inverter, or expecting the inverter to replace the controller when the manuals say otherwise, is how the battery gets the wrong voltage. The definition of the controller is in what a solar charge controller is. Keep that box in the diagram even when the shopping list only says “solar inverter.”
Write the job in one sentence before you compare brochures: follow the utility, form an island from a battery, or both after a listed disconnect. If the sentence needs two products, the quote should name both. A single box that claims every job still has to show the terminals and the listing for each job.
Frequently asked questions
Which type of solar inverter is best?
The one whose job matches the site. A reliable utility and a bill to cut point to a grid-tied inverter. No utility points to an off-grid inverter and a battery. Backup on a grid-tied house points to a hybrid or a separate battery system that can island, not to a larger grid-tied string inverter.
Is a microinverter a hybrid?
No. A microinverter is a small inverter at a module, usually grid-tied. Hybrid describes battery interaction and, sometimes, backup. The two words answer different questions. A product can be both only if the listing says both.
Can I use an off-grid inverter on a house that has utility power?
Not by tying it to the utility wires. An off-grid inverter forms its own supply. Connecting that supply to the grid without listed transfer equipment is a backfeed hazard. If the house has a utility, start with what the utility will interconnect.
Sources and references
Cease-to-energize and grid-support testing: NREL and Sandia IEEE 1547-2018 primer. Central versus string architecture, with dated capacity bands: ICF, 2017. Transformers on large central inverters: Pacific Northwest National Laboratory. Module-level shading recovery: NREL, 2016.
