Power outage is something we do not often encounter in the Netherlands, but when it happens, the impact can be significant. Especially if you rely on electric devices such as a heat pump, medical equipment, or simply lighting. A home battery offers the perfect solution as an emergency backup. But how exactly does it work? A home battery, if equipped with a backup function, can automatically continue to power critical devices when the grid power fails. This ensures that your home partially continues to function even when the rest of the neighborhood is without power. In this blog, we explain how a home battery works as a backup, what happens during a switch, and what you need to pay attention to in order to prepare your home properly. This way, you are not only acting more sustainably but are also prepared for unforeseen situations.

What does a home battery do during a power outage?

When the power goes out, a home battery with a backup function automatically initiates a switch. This is also known as “seamless switching.” The battery detects the outage and switches to the internal power supply within a few milliseconds. As a result, important devices like your fridge, lighting, or internet router continue to function without you needing to do anything. However, it is important to know that a home battery usually cannot supply power to your entire home for an extended period. Therefore, it is wise to choose which devices are essential during an outage. Often, these are:

• Fridge and freezer

• Basic lighting

• Heating (depending on the system)

• Internet and communication equipment

• Basic kitchen appliances such as a kettle or coffee maker

By setting priorities beforehand, you can efficiently utilize the available battery capacity during a power outage.

How does the switch from grid power to the home battery work?

The switch from the power grid to the home battery happens incredibly fast. A well-installed backup system typically switches within 20 milliseconds, which is so fast that your devices hardly notice it. There are two types of home batteries: systems that switch automatically and systems that need to be switched manually. For optimal protection, it's best to choose automatic backup systems. These can often be identified by an integrated ‘backup box’ or special backup output on the inverter. During the switch, your home is disconnected from the public grid (to prevent feeding back during a fault) and the home battery independently powers the selected circuits. Smart home batteries automatically distribute the available energy over essential devices, so you can use the stored power for as long as possible.

Choosing critical devices: What should you connect?

To make smart use of your home battery as an emergency backup, it is important to decide in advance which devices you want to continue using during a power outage. Consider a selection of critical devices essential for comfort, safety, and communication. Most households opt for:

• Fridge and freezer (prevents food spoilage)

• Basic lighting in the kitchen, living room, and hallway

• Router and modem for internet connection

• Phones or laptops to maintain contact

• Small heating appliances if possible

Keep in mind that large consumers like electric ovens, washing machines, or full heating systems demand too much energy for long-term backup. By making these choices in advance and installing them on a separate circuit, you can maximize the effectiveness of your home battery in case of an emergency.

How long can you rely on your home battery during a power outage?The duration you can rely on your home battery during a power outage completely depends on two factors: the storage capacity of your battery and the energy consumption of the connected devices. Suppose you have a battery with 10 kWh and your critical devices together consume approximately 1 kWh per hour, then you can bridge the gap for approximately 10 hours. By using your energy wisely – for example, by dimming lights or selectively turning on devices – you can extend the available time. Some advanced systems even have a ‘load shedding’ function, where less critical devices are automatically turned off if the battery capacity drops below a certain level. This allows you to remain operational as long as possible even during longer power outages. For longer periods of outage, it may be advisable to combine with a backup generator or alternative charging options such as solar panels, provided the system supports it.Why a home battery is becoming increasingly interesting as an emergency solutionWith the increasing risk of grid congestion, weather influences, and the growing use of electric devices at home, it's becoming more important to be prepared for power outages. A home battery not only offers financial benefits by making optimal use of solar energy and dynamic rates, but also provides extra security and independence. Thanks to the ability to keep essential devices running, you significantly increase your living comfort and safety. Moreover, with a good energy storage solution, you show that you actively contribute to a more stable and sustainable energy system. Investing in a home battery is therefore not only smart for your wallet, but also for the future-proofing of your home.Frequently asked questions about home batteries as an emergency power supplyCan every home battery provide emergency power during an outage?
No, only models with an integrated backup function can do this.How quickly does a home battery switch in the event of a power outage?
Within 20 to 50 milliseconds, almost without noticeable interruption.Should I connect my entire house to the battery?
No, only critical devices for maximum efficiency.Can I generate new power with solar panels during an outage?
Only if your home battery and inverter are suitable for it.How large should my battery be for a good backup?
Depending on your needs; 5-10 kWh is average for basic provisions.Do I lose a lot of energy during the switch?
No, the switch is almost lossless.Is an emergency backup standard included with a home battery?
No, you must specifically select this when purchasing.Can I also combine dynamic electricity prices with emergency power?
Yes, many modern systems support both functions.