Plug-in battery or fixed home battery: which fits you?

A plug-in battery is a compact unit you connect to an earthed wall socket yourself. A small meter in the fuse box, usually on the P1 port of your smart meter, sees when your solar panels generate more than you use. The battery then charges through the socket and feeds that power back to your home in the evening. It all runs automatically, with an app to watch along.

Capacity often starts around 1 to 2 kilowatt-hours; modular systems grow with extra units toward 5 kilowatt-hours or more. The big difference with a fixed system is power: a plug-in battery charges and discharges at about 800 watts at most, where fixed home batteries start around 2,000 watts according to Vereniging Eigen Huis (Dutch).

That 800 watts sounds abstract, but you notice it both ways. When charging: if your panels generate 2,000 watts more than you use on a sunny afternoon, the plug-in battery stores only 800 watts of that and the rest still flows to the grid. And when discharging: a kettle or washing machine alone asks more than the battery can deliver, so for those peaks you simply buy grid power. A plug-in battery mainly covers your base load: fridge, lighting, devices on standby.

For completeness: on nights when a small system runs empty, you simply run on grid power, nothing switches off. What a fixed system costs and when it pays back is covered in what a home battery costs.

With a fixed system, the installer takes care of a safe connection on its own circuit. With a plug-in battery that responsibility is yours, and it is stricter than many people think. Power reaches such a battery from two sides at once, from the grid and from the battery itself. The circuit breaker no longer sees the full picture, so wiring can overload without anything tripping.

The key rules: connect the battery to its own circuit, or otherwise to a circuit with few other loads. Always directly into an earthed wall socket, never via an extension lead or power strip. Keep it out of escape routes, in a ventilated room with a smoke detector. Those placement rules apply just as much to fixed systems; we list them in which home battery suits you.

Registration applies to both: Netbeheer Nederland (Dutch) designates Energieleveren.nl for it, the same portal used for solar panels. That includes plug-in batteries, as Vereniging Eigen Huis stresses too. Grid operators use the registration to plan the grid per neighbourhood.

A fixed home battery with a steerable inverter can do more than buffer solar power. Paired with a dynamic energy contract it also charges during the cheap hours of the day, and through grid control it helps the grid during peak moments in exchange for a payment. Plug-in batteries have their own app and sometimes a link to dynamic tariffs, but are harder to steer from an energy management system and generally do not take part in grid control.

Since late May 2026, a fixed home battery of 5 kilowatt-hours or more also counts toward your home's energy label, in combination with solar panels. That benefit only applies to fixed installations; a loose plug-in battery falls outside it. How the label benefit works is covered in our blog home battery counts toward your energy label.

We supply and install fixed home batteries, usually Dyness systems between 5 and 10 kilowatt-hours on a hybrid inverter. Still, advice conversations regularly start with the plug-in battery, and we get that: it is an accessible way to start with storage. Renting, living in an apartment without space near the fuse box, or wanting to first experience what storage does for you? Then a plug-in battery is a fine first step, and we will say so.

If you use serious power in the evening, have a heat pump or EV charger, or want to join grid control and dynamic charging, you outgrow a plug-in battery quickly. During the site survey we use your actual consumption to calculate what a fixed system delivers. Put your situation to us or start on our home battery page.