Can Solar Panels Work in an Outage Without a Battery?

By Hicham M. · Updated November 10, 2026

Usually not. A standard grid-tied solar system shuts off the moment the grid goes down, even at noon. A few inverter systems can keep some power flowing in daylight with no battery, but they top out around 2,000 W, stop when the sun does, and drop out when a cloud passes. Here's which ones, what that power can run, and what it costs.

Why rooftop solar goes dark in a blackout

Two things shut it down. The first is a safety rule. The U.S. standard for grid-connected inverters, IEEE 1547, requires them to detect an outage and stop sending power within 2 seconds (the utility can stretch that to 5). Line crews repairing a downed line need it to be dead, and a house quietly pushing solar power back into the wires would put them at risk.

The second is how ordinary inverters work. The Department of Energy describes most of them as “grid-following”: they lock onto the grid's voltage and frequency and can't run without it. Only a “grid-forming” inverter can create its own 60 Hz supply. Tesla's support page says it plainly: solar alone does not function during a power outage.

So any battery-less backup needs two pieces: an inverter that can form its own little grid, and a device that cuts the house off from the utility lines first.

The systems that can do it

System	Battery-less output	How it's delivered	Switching
Enphase IQ8 + Sunlight Backup	Loads at or under 30% of the array's AC rating (about 1.7 kW on a 5.7 kW system)	Up to 4 × 240 V or 8 × 120 V circuits in an essential-loads panel	Automatic
SMA Sunny Boy (-US-40) Secure Power Supply	Up to 2,000 W	One dedicated 120 V outlet	Manual
SMA Sunny Boy Smart Energy, Backup Secure	1,920 W	One 120 V outlet	Manual
SMA Sunny Boy Smart Energy, Backup Select	Rated 3,840 W or 5,760 W, but SMA doesn't say how much of that is available from solar alone	Seven 120 V circuits in a pre-wired panel	Automatic
Fronius Primo GEN24 PV Point	Up to 1.5 kW (U.S. product page)	One protected outlet	Not stated
EG4 18kPV, “PV Grid Off”	Not published	Inverter's backup output	Setting

From each maker's datasheets and manuals, checked October 2026. None of these work at night.

Popular systems that need a battery to back anything up include Tesla, SolarEdge Home Hub and Sol-Ark; their own documents say there's no backup without one. If your system uses older Enphase IQ7 microinverters, or a string inverter without one of the features above, it can't do battery-less backup, and Enphase doesn't support mixing IQ7 and IQ8 units on one system.

Enphase Sunlight Backup

This is the only option whose maker spells out what it can power on house circuits with no battery. It isn't a feature every IQ8 system has, though. Enphase's installer brief lists the parts: IQ8 microinverters, an IQ System Controller 2 (the IQ System Controller 3 also supports it), an IQ Combiner 4/4C, at least one IQ Load Controller, an Enphase System Shutdown Switch for the electrical code's rapid-shutdown rule, and a separate panel for the essential circuits. The brief warns that the original IQ System Controller 1 is not safe to use with IQ8s.

Enphase sets the limits itself:

Keep backup loads at or below 30% of the array's rated AC output. Its example: 24 IQ8s make 5.7 kW AC, so about 1.7 kW of loads.
At most 4 circuits at 240 V or 8 at 120 V. Backing up the whole home “will lead to poor experience and is not supported”.
If the loads need more than the panels are making at that moment (a cloud, snow, or too many appliances), the backup shuts off. With sunlight available it can take up to two minutes to restart, and loads come back one at a time, 22 seconds apart.
A load that causes five shutdowns is switched off until you turn it back on in the Enphase app.
It only works while the sun is up. You can add an IQ Battery later and reuse the same System Controller.

Is it still sold? Enphase's installer page still describes it in November 2026, but its newest Sunlight Backup documents date from April 2023, and an Australian solar site reported in 2023 that it had been withdrawn. Ask an Enphase installer whether they'll install it before you plan around it.

SMA's emergency outlet

SMA took a simpler route. Older Sunny Boy -US-40 inverters have Secure Power Supply: a dedicated outlet that gives up to 2,000 W in daylight when you flip a switch during an outage. You run an extension cord from it to whatever you need. SMA's manual warns that the output can swing a lot with the weather; when the load is too big or the sun fades, the outlet cuts out and tries again after 20 seconds, which can restart whatever is plugged in. It also isn't compatible with SMA's rooftop rapid-shutdown kit, which many newer installs need.

The current Sunny Boy Smart Energy line keeps the idea as Backup Secure: 1,920 W at 120 V, switched on by hand, with or without a battery. Installs that fall under the rapid-shutdown rule need SMA's Backup Start module for it. The newer Backup Select panel switches seven 120 V circuits automatically, and its datasheet says it offers partial backup with or without a battery, but SMA's manual describes it as battery backup and doesn't publish how much power it gives from solar alone.

What about 2,000 W of sunshine can run

All of these land near the same ceiling: roughly 1.5 to 2 kW, daytime only, with nothing in reserve for a motor starting. That last part catches people out. A fridge runs on about 150 W, but its compressor needs around 1,200 W for a moment when it kicks on.

Loads	Running	Peak at start	Verdict
Light essentials Router, laptop, 3 LED bulbs, box fan	167 W	242 W	Fits in full sun
Essentials + fridge Adds a full-size ENERGY STAR fridge	317 W	1,367 W	Fits in full sun
Essentials + fridge + microwave Microwave on while the fridge runs	1,817 W	2,867 W	Too much
Fridge + sump pump Router, lights, fridge and a 1/2 HP sump pump	1,242 W	2,342 W	Too much

Typical wattages from our appliance data, with everything on at once. Your appliances may differ; check them in the runtime calculator.

“Fits in full sun” is the best case. The budget is whatever the panels are producing that second, and clouds move fast: researchers in the Netherlands measured a swing of about 750 W per square meter between sunlit and shaded ground under cumulus clouds, with shadow edges only 40 to 60 m wide. On a patchy day, a fridge compressor starting just as a cloud arrives can knock the whole backup offline.

In practice, battery-less backup handles phone and laptop charging, the internet, lights, fans and maybe a fridge on a clear day. A sump pump, well pump or air conditioner is out of reach, and so is anything at night.

The night problem, and a workaround

Most outage hours now come from major storms. The EIA counted 11 hours without power per customer in 2024, the most in ten years, and hurricanes caused most of it. A system that stops at sunset leaves you without the fridge, CPAP and lights overnight.

If you have one of these systems, a portable power station closes the gap. Charge it from the backup outlet or circuit while the sun is out, then run your essentials from it after dark. Set its AC charging rate low so the charger doesn't eat the whole solar budget; several models, such as EcoFlow's DELTA 3 Plus, let you lower the AC charging speed in their app. Then size the station for your overnight loads with the size finder.

If you don't have a compatible inverter, the station plus its own portable panels does the same job with no electrician. The solar charging calculator shows how fast a given panel refills it.

What it costs

Option	Cost	Notes
Enphase Sunlight Backup add-on	Roughly $3,000 to $3,500 in parts, plus labor	Our estimate from 2026 retail prices: about $2,200 to $2,300 for an IQ System Controller 3, $449 to $629 per IQ Load Controller, plus the shutdown switch. Requires IQ8s already on the roof.
SMA outlet	Included with the inverter	The outlet and switch still need to be installed.
Home battery (13.5 kWh)	About $15,650 before incentives	EnergySage marketplace quotes, first half of 2026
Portable power station	From a few hundred dollars	No installation. Compare models in the size finder.

One change for 2026: the 30% federal tax credit for home solar and batteries (section 25D) has ended. The IRS says it isn't allowed for expenses made after December 31, 2025, and an expense counts as made when the installation is finished. Older cost guides that subtract 30% are out of date.

Safety

Battery-less backup has to be installed by an electrician with a permit. Under the National Electrical Code, an Enphase setup like this counts as a microgrid, and the System Controller is the device that isolates it from the grid.
Never feed power into a wall outlet or your panel to run the house (“backfeeding”). It can energize the utility's lines and hurt the people fixing them.
Your panels still produce dangerous voltage in daylight during an outage, even when the inverter is off.
Don't rely on a sun-only system for medical equipment. A cloud can cut it off without warning.

Can Solar Panels Work in an Outage Without a Battery?

Why rooftop solar goes dark in a blackout

The systems that can do it

Enphase Sunlight Backup

SMA's emergency outlet

What about 2,000 W of sunshine can run

The night problem, and a workaround

What it costs

Safety

Sources

Keep reading

Calculators

Runtime calculator

What size do I need?

Solar charging calculator

Real-world runtime simulator

Winter outage simulator

Generator vs power station

Compare models