Solar inverter types compared: string, hybrid, off-grid & micro

By the SmartSolarSizer team · Published 10 August 2026 · Updated 9 November 2026

Quick answer

Pick the inverter by what happens when the grid goes down. A string (on-grid) inverter is the cheapest way to cut your bill but shuts off in a power cut. A hybrid inverter adds a battery and keeps the lights on, which is why it suits load-shedding in Pakistan and India and the lower export rates of net billing. Off-grid inverters run without any grid, and microinverters or optimisers suit shaded, awkward roofs. Peak efficiencies are close, from about 93% to 99%, so warranty, surge and support matter more than the decimal points.

The four types at a glance

Type	Power in a grid outage?	Battery?	Example peak efficiency	Best for
String (on-grid)	No, it shuts down	No	97.0% (SMA Sunny Boy 5.0)	Cutting bills where the grid is reliable
Hybrid	Yes, from battery and panels	Yes	97.6% (Deye 5 kW hybrid)	Load-shedding, net billing, adding storage
Off-grid	Yes; there's no grid to lose	Required	93–95% (Growatt SPF, Victron)	No grid connection, or a separate backup system
Microinverters	Only with an Enphase battery or Sunlight Backup kit	Optional	97.7% (Enphase IQ8)	Shaded or split roofs, panel-level monitoring
String + optimisers	No, unless paired with a battery inverter	Optional	99.2% inverter (SolarEdge Home Wave)	Partly shaded roofs, panel-level safety

Efficiencies are each example model's peak figure from its datasheet; other models differ.

Why most solar inverters switch off in a power cut

A grid-tied inverter must not keep feeding a power line the utility has switched off, a situation called islanding, because it endangers line workers and equipment (NREL). The US standard IEEE 1547-2018 requires an inverter to stop feeding an islanded line within two seconds (NREL). The US Department of Energy says standard inverters disconnect and shut down when a grid disruption is long or large, and solar-plus-battery systems keep running only if they are designed to (DOE). Panels on the roof and a sunny sky don't change that.

String (on-grid) inverters

One box converts power from one or two strings of panels and sends it to the home and the grid. The SMA Sunny Boy 5.0, a typical example, reaches 97.0% peak and 96.5% European weighted efficiency, with two separate MPPT inputs (SMA). Two MPPTs let you put panels on two roof faces without one dragging the other down.

Choose one if your grid is reliable and your main goal is a lower bill. Skip it if you get regular outages, or want a battery later without replacing the inverter. A few models offer a small daytime emergency outlet; SMA's US Secure Power Supply gave 2,000 W while the sun shone (retailer listing), but that's no substitute for a battery.

Hybrid inverters: the best choice for load-shedding

A hybrid combines a solar inverter, a battery charger and a backup supply. Deye's 5 kW SG04LP1 hybrid takes a 48 V battery (lithium or lead-acid), reaches 97.6% peak efficiency, has two MPPTs and a 5-year warranty, extendable to 10 in some countries (Deye datasheet). A distributor lists the similar SG03LP1's switch from mains to battery at 4 ms or more (distributor), fast enough that most appliances don't notice.

That's why hybrids have spread where the grid is unreliable. Business Recorder reports that hybrid setups are now common in Pakistan as battery prices fall and supply stays unreliable (Business Recorder). In Uttar Pradesh, hybrid rooftop systems are emerging because conventional rooftop solar stops supplying homes during blackouts (Earth Journalism Network). Hybrids also suit net billing: when exports pay little, the battery stores midday surplus for the evening. Size the battery with our battery calculator.

Watch out for the surge rating if you run ACs or pumps, and the heat: some hybrids keep full power only up to 45 °C. Check yours with the inverter temperature derating calculator.

Off-grid inverters

Off-grid inverter-chargers build their own supply from batteries and panels, with no grid needed. The Growatt SPF 5000 is typical: 48 V battery, 93% peak efficiency, and a 10–20 ms transfer time when it switches sources (Growatt datasheet). Victron's MultiPlus-II 48/4k5 reaches 95% and can deliver 7 kW for a minute to start motors. It also draws 20 W just switched on with no load, 8 W in search mode (Victron datasheet), which matters on a small battery overnight.

Types of off-grid solar inverter. Off-grid models differ in three ways worth checking. The solar charger is either MPPT, which gets noticeably more from the panels, or cheaper PWM. The output is pure sine wave, which every appliance accepts, or modified sine wave, which can make motors, fans and some chargers hum or run hot. And the design is high-frequency, which is light and cheap, or low-frequency with a heavy transformer, which copes better with motor start-up surges. For a home, look for MPPT and pure sine wave at minimum.

Choose one for a cabin, farm or home with no grid, or as a separate backup system. Some models, like the Victron, can also feed the grid in certain setups, so check before you assume either way.

Microinverters

Microinverters put a small inverter behind each panel. Enphase's IQ8+ gives 290 VA continuous (300 VA peak) per unit with 97.7% peak and 97% CEC weighted efficiency, a warranty of up to 25 years, and its own MPPT for every panel (Enphase datasheet). One shaded or dirty panel no longer pulls down the whole string, and you can see each panel's output.

Standard microinverters still shut down in an outage. Enphase's Sunlight Backup lets IQ8 systems power essential, low-power devices during daytime outages without a battery, with the right load controller (Enphase). The listed IQ8 models are for US 240 V split-phase supply, so check what's sold where you live.

String inverters with power optimisers

A middle path: an optimiser behind each panel and one central inverter. SolarEdge's Home Wave inverter reaches 99.2% peak efficiency and allows up to 200% DC oversizing (SolarEdge datasheet). Its optimisers reach 99.5% and drop to 1 V each when shut down (SolarEdge optimiser datasheet). Warranties are 12 years for the inverter (7 in some countries) and 25 years for optimisers (SolarEdge warranty).

How big should the inverter be? DC:AC ratio and clipping

Inverters are often smaller than the panel array, because panels rarely reach their full rating. When the panels could make more than the inverter can pass, the extra is cut off, which is called clipping (NREL). NREL calls 1.2–1.5 the typical ratio of panel to inverter capacity in new large systems (NREL), and LBNL found US utility-scale projects averaging around 1.3 (LBNL). Homes vary more, and your inverter must also cover your biggest load and its start-up surge, not just your panels.

What to check before buying

Surge rating against your biggest motor. A non-inverter AC or well pump can need several times its running power for a moment. Our well pump and 1.5 ton AC guides show the numbers.
Battery voltage and type. Most home hybrids use 48 V. Check the battery brands the inverter is approved to talk to.
Output in heat. Victron rates its inverters at 90% of output at 40 °C (Victron). If yours lives somewhere hot, check its derating curve.
Number of MPPTs. Two or more if your panels face different ways.
Warranty and local service. A 5-year warranty with a nearby service centre can beat a 10-year one with nobody to honour it.
Grid approval and safety rules. Check the model is approved by your utility. In the US, rooftop systems must meet rapid shutdown rules that bring conductors down to safe voltages within 30 seconds for firefighters (NEC 690.12 summary).

Common questions

Which type of solar inverter is best for load-shedding?

A hybrid inverter with a battery. It switches to the battery within milliseconds when the grid fails and keeps running from the panels in daylight. An ordinary on-grid inverter shuts down in an outage.

Can a hybrid inverter work without a battery?

Many can run as an on-grid inverter with no battery, but then they can't supply backup power reliably. Check the datasheet; some need a battery to run in off-grid mode at all.

Is a microinverter better than a string inverter?

On shaded or multi-direction roofs, often yes, because each panel works on its own. On a simple, unshaded roof, a string inverter is usually cheaper with similar efficiency. Microinverters also carry longer warranties.

Can I add a battery to my existing on-grid inverter?

Usually not directly, because an on-grid inverter has no battery connection. The options are a separate battery inverter wired alongside it, or replacing it with a hybrid. Ask your installer which your system supports.

What are the types of off-grid solar inverter?

They're grouped by solar charger (MPPT or PWM), output waveform (pure sine or modified sine) and design (high-frequency or low-frequency transformer). For a home, choose MPPT with pure sine wave output; low-frequency models handle motor surges such as pumps and ACs better.

How long do solar inverters last?

Warranties give a guide: 10 to 12 years is common for string inverters (SolarEdge offers 12), 5 to 10 years for Deye hybrids, and up to 25 years for Enphase microinverters. Panels usually outlast the first inverter.

Do solar inverters lose power in hot weather?

Yes, above their derating temperature. Victron rates its inverters at 90% of output at 40 °C and 69% at 65 °C. Keeping the inverter shaded and ventilated helps most.

Find the inverter size you need

Add your appliances and the calculator gives the inverter size and surge rating, with the panels and battery to match.

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Sources

Every figure on this page comes from these sources, checked on 30 October 2026.