How does a home battery work?
A home battery works by storing power when you have some to spare and releasing it again when you need it. During the day the battery charges with solar power or cheap power from the grid, and in the evening and at night it delivers that power back to your home. An inverter, a battery management system and your smart meter handle that process fully automatically.
What is a home battery?
A home battery is a rechargeable battery that stores electricity in your home for later use. You'll also often come across the term home storage battery; it means the same thing. You can see which versions are available, for example compact plug-in models or fixed systems in the meter cupboard, in the overview of all home batteries.
The reason for getting a home battery is almost always the same: you want to use more of your own power yourself. According to Milieu Centraal, on average you use about 30 percent of the power your solar panels generate directly yourself. The rest goes to the grid, because your panels mainly generate during the day while you use most of your power at other times, such as in the evening. A home battery shifts part of that surplus to the evening.
How does a home battery work step by step?
A home battery works step by step in a fixed daily cycle of charging, discharging and exchanging with the grid. During the day the battery fills up with power you don't use right away, and in the evening it gives that power back. You don't have to do anything for this yourself: the system continuously measures how much power you generate and use, and adjusts the charging and discharging accordingly.
That daily cycle carries even more weight now that net metering is no longer possible from 1 January 2027. For electricity you feed back, you'll then get a payment that, until 2030, amounts to at least 50 percent of the bare supply rate. Every kWh you use yourself then earns you more than a kWh you feed back.
How does a home battery charge with solar power?
A home battery charges with solar power as soon as your solar panels generate more than your household is using at that moment. If only the fridge is running while the sun is shining brightly, the surplus goes to the battery instead of the grid. Your panels generate direct current, which goes into the battery either directly or via an inverter, depending on the system. The battery keeps charging until it's full or until your usage is higher than your generation again.
How does a home battery supply power to your house in the evening?
A home battery supplies power to your house in the evening as soon as your consumption is higher than what your solar panels are still generating. At that point the battery discharges: the inverter converts the stored direct current into alternating current for your lighting, TV and cooktop. You won't notice any of this in your home, because the switch between solar power, battery power and grid power happens automatically. Your sockets work exactly as they always do.
What does a home battery do when it's full or empty?
A home battery that's full simply lets the surplus solar power flow through to the electricity grid. If the battery is empty, you automatically draw power from the grid again, according to Milieu Centraal. So as long as the grid is working, you're never without power, not even when the battery runs out at the end of the evening. The home battery acts as a buffer between your solar panels, your consumption and the grid, not as a replacement for your grid connection.
What parts make up a home battery system?
A home battery system consists of four parts that work together to store power safely and release it again. In an all-in-one model they sit in a single enclosure. In a modular system you stack separate battery modules on a main unit with the inverter, so you can expand the capacity later. Here are the parts and what they do:
- Battery cells: store the energy as a chemical charge; according to Milieu Centraal, most home batteries use lithium iron phosphate (LFP) cells, a stable cell type for everyday use in the home.
- Inverter: converts the direct current (DC) from your solar panels and battery into the alternating current (AC) used by your home and the grid, and vice versa.
- Battery Management System (BMS): continuously measures the voltage, current and temperature of the cells and prevents them from being overcharged, discharged too deeply, or getting too hot.
- Energy Management System (EMS): decides when the battery charges and discharges based on your generation, your consumption and, where relevant, the electricity price.
These parts work together constantly. The BMS protects the battery cells, the inverter makes the stored power usable for your devices, and the EMS controls the whole system. In many home batteries the inverter is built in, while in others the battery shares the inverter with your solar panels.
How does a home battery know when to charge?
A home battery knows when to charge because it usually measures, via the P1 port of your smart meter, how much power you draw from and feed back to the grid. When you feed power back, the battery starts charging. When you draw power, the battery discharges as much as your home needs at that moment, up to its maximum discharge power.
That measurement runs through a P1 meter that you plug into the P1 port of your smart meter, like the Zendure Smart Meter P1. The energy management system uses that data to control the battery. If you have a dynamic energy contract, the system also takes the fluctuating electricity prices into account.
A home battery's capacity versus power
When it comes to a home battery's capacity versus power, you're dealing with two values that together determine what the battery can do. Capacity tells you how much energy fits inside, power tells you how fast that energy can go in or out. According to Milieu Centraal, the capacity of home batteries ranges from roughly 2 to 20 kWh, with an average around 6 kWh. Here's a quick overview of the terms:
- Capacity (kWh): the amount of energy the battery can store, which determines how long you can run on battery power.
- Charging power (kW): the speed at which the battery charges, which determines how much solar power it captures on a sunny afternoon.
- Discharge power (kW): the amount of power the battery can deliver at once, which determines how many devices can run on battery power simultaneously.
A battery with lots of capacity but a low discharge power covers a long evening of light usage just fine, but won't handle a peak from a kettle and a hob running at the same time. If your home needs more power than the battery delivers, the grid automatically makes up the difference.
How does a home battery work with solar panels?
A home battery works with solar panels via either an AC coupling or a DC coupling. The difference lies in where the battery connects to your installation and in how many times the power gets converted. The coupling determines whether your existing inverter can stay in place and how much energy is lost during storage. If you already have solar panels, that's the first question to answer.
An AC-coupled home battery
An AC-coupled home battery has its own built-in inverter and connects to the alternating current side of your installation. That means your existing inverter for the solar panels simply stays in place. The power does get converted more often: to alternating current in your solar panels' inverter, back to direct current in the battery, and to alternating current again when discharging. That costs a little energy, but makes the battery suitable for almost any existing solar installation.
A DC-coupled home battery
A DC-coupled home battery shares one inverter with your solar panels and stores the panels' direct current right away. Because the power is converted less often, less energy is lost. On the other hand, you usually need a hybrid inverter that can handle both the panels and the battery. With an existing installation, that often means a new inverter, which makes DC coupling especially interesting for a new installation.
How does a home battery with a plug work?
A home battery with a plug works the same way as a fixed home battery, except you connect it through a power outlet instead of its own circuit in the meter cupboard. A plug-in home battery charges with power from your solar panels or the grid and feeds it back to your home installation through that same outlet. For a plug-in system, you usually need the following:
- Power outlet: an earthed outlet on a circuit without other heavy appliances.
- Smart meter: a meter with a P1 port, read out by the system's P1 meter.
- App: a connection via wifi or bluetooth to set up and monitor the battery.
- Registration: a notification to your grid operator via Energieleveren.nl at a power of 0.8 kW or more.
Milieu Centraal points out that with a plug-in battery, power can come to one circuit from two directions, from the grid and from the battery, without the fuse stepping in. If a washing machine or dryer is also on the same circuit, the wiring can get too hot. If you're unsure about your fuse box, have an installer take a look.
Does a home battery work without solar panels?
Yes, a home battery works without solar panels too. The battery then charges with power from the grid instead of with your own solar energy. That's especially interesting with a dynamic energy contract, where the electricity price moves with the energy market throughout the day. The battery charges when power is cheap and discharges when the price is high.
So a home battery without solar panels shifts your power purchases to cheaper moments. According to Milieu Centraal, some larger batteries can also feed power back to the grid during expensive moments, letting you take advantage of the price differences.
Does a home battery work during a power outage?
A home battery doesn't work automatically during a power outage. A regular grid-connected battery switches off as soon as the grid goes down, even if it's full. That shutdown prevents voltage reaching the grid while technicians are fixing a fault. So for a standard system, how full your battery is at that moment makes no difference.
If you want to keep power during an outage, you'll need a home battery with backup power. A system with a backup power function disconnects your home, or part of it, from the grid and feeds it from the battery. How long that lasts depends on the battery's charge and on the devices you keep running.
Does a home battery make you self-sufficient?
No, a home battery doesn't make you self-sufficient, not even combined with solar panels. Milieu Centraal does the math with 10 solar panels, which together generate roughly 3,500 kWh per year. On an average June day, those panels deliver about 15 kWh, more than an average 6 kWh home battery can store. On an average December day that's about 2.5 kWh, too little to fill the battery.
So you'll still depend on your grid connection: in summer for the surplus, in winter for the shortfall. What a home battery does do is keep more of your own solar power in the house. That way, you draw less power from the grid at the moments your panels aren't generating anything.
Choosing a home battery at TechPunt
Choosing a home battery at TechPunt starts with how you want to use it: for more of your own solar power, to charge during cheap moments, or as a buffer during power outages. Our range includes plug-in home batteries from Zendure and Anker SOLIX, modular systems from Zendure, and the smart meters to control them. Every home battery ships from our own warehouse in Barneveld, with a 2-year manufacturer's warranty.
Take your time comparing the systems on capacity, power and coupling. Not sure which system suits your installation? Get in touch with our customer service by phone, email or WhatsApp.
