Adding a battery and back-up to Enphase micro-inverters

Yes. Solar panels with micro-inverters can get a battery and real back-up for the whole house, without touching the roof. The battery always sits next to the micro-inverters, with its own inverter. A home battery with micro-inverters is designed around three questions: how many phases, which circuits must keep running, and for how long. The brand of your micro-inverters decides which route is simplest.

Maybe you chose micro-inverters years ago for good reasons. A complex roof with several sides, a chimney that throws shade, panels that each do their own work. Now there is a heat pump, one or two electric cars, and a digital meter that pays little for your surplus. Then the power goes out one afternoon. The sun is shining, and every micro-inverter on the roof stops.

Belgian owners ask the same questions on forums. One has 16 Enphase IQ7+ micro-inverters on a single-phase 40 A connection. He asks whether a battery inverter added later "counts" toward his limit. A Flemish owner with three-phase Enphase wants the whole house on back-up behind a battery system in his garage. French owners even try to "fool" their micro-inverters with a car battery and a converter. Forum experts warn that it is dangerous and does not work.

What most offers leave out is where the real work sits. A brand battery of 5 kWh is quick to add, but it is not back-up by itself. In a three-phase house, back-up on one phase keeps the lights on while the heat pump stops. Buy storage first and add back-up later, and you often pay for part of the system twice.

Our projects with existing solar installations show the principle. In Lokeren, the solar panels and inverters stayed in place and were combined with a BYD LVS battery of 16 kWh. In Kortenberg, a three-phase system of 9 kVA gives the house full back-up in off-grid mode.

Can you connect a battery to micro-inverters?

Yes, but not directly. A micro-inverter sits under each panel and turns its direct current into 230 V straight away. There is no central box with a battery input.

So the battery comes with its own inverter, connected on the AC side of the house. This is called AC coupling. You do not need a hybrid inverter, and nothing changes on the roof. Your micro-inverters keep working as they do today, and the battery system stores the surplus they send into the house.

Do you have a string inverter from SMA or SolarEdge instead? Then read our article on adding a battery to an existing SMA or SolarEdge installation, because that inverter changes the choices.

What does the Enphase battery give you, and where are its limits?

The Enphase IQ Battery 5P is an AC-coupled battery of 5.0 kWh. It has six built-in micro-inverters and delivers 3.84 kVA continuously. Enphase gives a 15-year warranty, up to 6,000 cycles.

For Belgium and the Netherlands, Enphase's planning guide lists the 5P as compatible with its IQ7 and IQ8 micro-inverters, and even with a string inverter. The older M Series, such as the M215 and M250, cannot share a gateway with the 5P. They need a separate gateway. So the first question is which generation of micro-inverters is on your roof.

Back-up is a separate device. The datasheet of the IQ System Controller 3 INT says it detects a power cut and switches the house to back-up. It supports IQ7 and IQ8 micro-inverters and main breakers up to 80 A. Its datasheet gives a switchover time of under 120 milliseconds. Without the controller, the Enphase battery works only while the grid is there.

Three phases need extra care. In July 2026, Enphase opened back-up for owners of its older IQ Battery 3T and 10T in Belgium and twelve other countries. Single-phase homes get whole-home back-up, but three-phase homes back up one chosen phase. Back-up on all three phases needs the 5P with FlexPhase and an IQ System Controller.

For a large home, do the sums. One 5P gives 5 kWh and 3.84 kVA. In three-phase mode, a 5P with FlexPhase spreads that power: 1.28 kVA per phase. Three of them give 15 kWh and 3.84 kVA per phase. Check that against a heat pump, a cooker and a car charger that start at the same moment.

What about APsystems micro-inverters?

APsystems has its own AC-coupled storage family, APstorage. It works with APsystems micro-inverters and, according to APsystems, with third-party inverters too.

The single-phase ELS-5K delivers 5,000 VA and up to 7,500 VA peak in back-up. The three-phase ELT-12 delivers 12,000 VA and up to 18,000 VA peak in back-up. The APbattery modules are LFP batteries of 5 or 10 kWh, expandable to 160 kWh. APsystems' datasheet of the smaller ELS-3K names a back-up mode to secure critical loads during outages.

What the datasheet does not tell you is how your house is wired behind it. Which circuits move to the back-up board, and what happens to the micro-inverters on the roof when the street goes dark? The installer decides that, not the battery. Some owners also have Hoymiles or other brands. The same questions apply to them: grid-forming battery inverter, a separate back-up board, and settings that let the micro-inverters produce in an outage.

Can an independent battery system such as Victron work next to micro-inverters?

Yes. Victron writes that most brands of solar inverters can be AC-coupled to its systems. They must be set up for frequency shifting, often called island mode or micro-grid mode.

Frequency shifting is how the battery inverter controls the solar power in an outage. When the battery is full, it raises the frequency of the house grid, and the micro-inverters throttle back. That setting lives in the micro-inverters' grid profile, so someone with access to your Enphase or APsystems gateway must check it. We connect almost all inverter types to a home battery, and we check your micro-inverter model first.

Three rules come from Victron's AC coupling documentation. The solar power on the output may not exceed the continuous power of the battery inverter at 25 °C. For lithium, count at least 4.8 kWh of battery per 1.5 kWp of AC-coupled solar power. And with micro-inverters, count that per phase, because every micro-inverter feeds one phase. Our article on SMA and SolarEdge works these rules out in a chart.

One more point from a German forum. An owner with Enphase and a three-phase Victron system found that his back-up handled a full outage well, but not the loss of one phase. Ask how your design detects a missing phase, not only a dark street.

Will your micro-inverters keep working in a power cut?

Not without a battery system that forms its own grid. A micro-inverter switches off when the public grid fails, so it never sends power onto a cable that a technician thinks is dead.

That is also why the car-battery trick is dangerous. A grid-tied micro-inverter pushes power out; a small converter cannot absorb it. With a real back-up system, the battery inverter first separates your house from the street. Then it forms a house grid, and the micro-inverters start again on it.

Speed matters for computers and network equipment. Our home battery systems take over within 20 milliseconds, so computers keep running. Our guide to a home battery with back-up power explains the three levels of back-up, from a few sockets to the whole house.

Single-phase micro-inverters in a three-phase house: what does full back-up need?

Most micro-inverters are single-phase devices. In a three-phase house they are spread over the phases, or they all sit on one.

That spread decides the design. On a single-phase connection in Flanders, a battery may have at most 5 kVA of inverter power. On more phases, the difference between phases may not exceed 5 kVA. A heat pump or a car charger on 3 x 400 V needs all three phases in an outage. The house in Wetteren runs fully on back-up on three phases, and so does the one in Kortenberg.

Before the design, answer four questions:

Want the full picture on phases? Read whether you need a three-phase home battery for full back-up.

What happens in a long winter outage?

Micro-inverters need a grid to start. In an outage, only the battery can give them one. If a cold night empties the battery, the house stays dark in the morning, even in full sun.

Enphase names two recovery functions for its systems, Blackstart and Sunlight Jumpstart. For AC-coupled systems in general, Victron calls solar chargers on the DC side necessary for back-up systems that must bridge long grid failures. A few extra panels on a solar charger feed the battery directly, without needing the micro-inverters.

In Roosdaal, the single-phase system was at its maximum of 5 kVA of inverters. A new solar charger (MPPT) that feeds the battery directly added energy without the cost of a grid study. In Maaseik, an existing generator was connected to the home battery in off-grid mode. Read how a generator recharges a home battery in a power cut of several days.

Which rules apply when you add a battery to micro-inverters?

The same rules as for any home battery. In Flanders, the battery is inspected under the AREI and registered with Fluvius.

• Registration. You register a home battery with Fluvius within 30 days of the inspection, via Mijn Fluvius for systems below 25 kVA.
• Inverter limits. Single-phase at most 5 kVA of battery inverter power, multi-phase at most 25 kVA, with at most 5 kVA of difference per phase.
• Back-up wiring. Circuits that move to a back-up board change your installation, so they are inspected before use.
• Green certificates. The battery does not touch the certified micro-inverters, but ask before any change to the solar installation.

How your solar and battery inverters are counted together is explained in our article on registering a home battery and the Synergrid list. In Wallonia and Brussels, you declare the battery to ORES, RESA or Sibelga under their own rules. Do your micro-inverters trip at noon on sunny days? Then first read why solar inverters switch off when the grid voltage is too high.

When is the brand battery enough, and when is a separate battery system better?

Both routes are good. The right one depends on what you want in an outage.

We would rather tell you that the brand battery is enough than sell you a system you do not need. And if your panels hang on a balcony with a plug-in micro-inverter, read first what a plug-in battery can never do. For a large home, our guide on how big a home battery should be helps you size it. Going further, a micro-inverter installation can also be part of an off-grid system.

How do we add a battery to your micro-inverters?

We control the whole cycle: measuring, design, installation and follow-up. Our team includes three certified battery experts.

1. Step 1: Your installation first. You send the brand, model and number of your micro-inverters, the phases of your connection and whether you receive green certificates.
2. Step 2: Measuring. We measure beforehand, so the battery and the back-up fit your real use.
3. Step 3: Design. We choose the route, which circuits get back-up and how an empty battery restarts.
4. Step 4: Installation, inspection and registration. The installation is inspected under the AREI and registered with your grid operator.
5. Step 5: Follow-up. You follow production, storage and use in the VRM app and portal, and the system can be monitored and controlled remotely.

We also maintain and repair battery systems that are already installed, and we can revise an existing battery.