Solar battery and NBN backup during Perth power outages

During a power outage, most Perth households lose their internet connection. If you have a home battery system with backup power capability, you may be able to keep the internet running — but whether it works depends on your NBN connection type, your router, and how your battery backup is configured. Here's what to know.

The four NBN connection types and power requirements

FTTP (Fibre to the Premises): The NBN box (NTD — Network Termination Device) is installed in your home. The NTD requires mains power. Without power, the NTD is off and your internet connection drops. During an outage, you need to power the NTD to maintain your internet service.

The NTD typically consumes 5–10W (small, low-power device). Your router adds 5–15W. Total power draw for basic internet: ~10–25W — very low.

FTTN/FTTB (Fibre to the Node/Building): The internet signal comes through the copper phone line from a street-side node. Your home router connects directly to the phone socket — no in-home NBN box. The NBN node itself has backup power (batteries maintained by NBN Co). Your internet connection may survive the outage without needing home battery backup — IF your copper line and the node both remain operational.

In practice, FTTN/FTTB internet often stays connected during Perth power outages for several hours (while the node's batteries last), with no in-home power required beyond your router.

FTTC (Fibre to the Curb): Similar to FTTP — there's a DPU (Distribution Point Unit) at the street and a small NTD in your home. The NTD requires power. Outage = internet off unless you power the NTD.

HFC (Hybrid Fibre Coaxial): Uses cable connection (like old Foxtel cable). An HFC NTD in your home requires mains power. Outage = internet off unless you power the NTD.

What you need to keep the internet running during an outage

For FTTP, FTTC, and HFC connections (where an NTD in your home needs power):

1. A battery system with EPS (Emergency Power Supply) capability — standard grid-tied solar/battery systems shut down during outages per anti-islanding requirements. Only EPS-capable battery systems can power loads during an outage.

2. The NTD and router on the backup circuit — if your EPS system only backs up specific circuits, ensure your router and NTD are plugged into a GPO (general power outlet) on the backed-up circuit. Many EPS systems back up a single dedicated "backup" circuit or specific GPOs.

3. Adequate battery capacity — the power draw is minimal (10–25W). A 10kWh battery at 10–25W load theoretically lasts 400–1,000 hours. In practice, you'll have other EPS loads (phone charging, fridge, lighting) reducing this.

For FTTN/FTTB connections: Your internet may survive the outage already, since you only need to power your router (5–15W) from battery backup.

Important limitations

NBN Co battery backup policy (FTTP/FTTC): NBN Co removed their Battery Backup Unit (BBU) from residential FTTP/FTTC installations after 2017. The in-home NTD no longer comes with NBN-provided battery backup. If your connection type needs the NTD powered, you are responsible for backup power.

EPS system limitations: Not all EPS systems can power NTDs. Some NTDs require a stable sine wave output — all reputable EPS battery systems (Sungrow, Goodwe, SolarEdge, BYD) provide pure sine wave output, so this is generally not an issue. UPS (Uninterruptible Power Supply) devices also work for just the NTD and router.

EPS transfer time: When the grid fails, EPS systems take 20–40ms to transfer to battery backup. Most electronics (routers, NTDs) tolerate this brief interruption. If your router frequently drops connection during outages even with a UPS, check if your router requires a longer ride-through time.

Emergency calls: Even if your internet drops, most mobile networks provide coverage for 000 emergency calls. If you have a medical emergency during an outage, use a mobile phone — don't depend on VoIP (internet phone) during a power failure.

Simple backup option for internet only: a UPS

If you don't have a home battery system but want to keep the internet running during short outages, a small UPS (Uninterruptible Power Supply) is the simplest and cheapest option:

• A basic 600VA APC Back-UPS or similar ($80–$150 from Officeworks or online) can power a modem/router and NTD for 2–4 hours during an outage
• UPS devices plug into the wall and automatically switch to battery when power fails — no solar or battery system required
• This is NOT a substitute for a home battery system (no solar self-consumption benefit, no EPS for other loads) but is a cost-effective fix specifically for internet backup

For Perth households who simply want their internet to survive short storms or Western Power maintenance outages, a UPS is often the most practical solution.

With a home battery system

If you have a battery system with EPS mode, configure it so that the router and NTD (if applicable) are on the backed-up circuit. This is usually as simple as plugging those devices into a GPO that's in the EPS zone. Ask your installer to show you which circuits or GPOs are backed up by EPS.

The internet draw is so low that it will have negligible impact on your battery's backup duration for other loads (fridge, lighting, phone charging).

FTTP, FTTC, and HFC connections require the in-home NTD to be powered — a home battery with EPS can keep the internet running, or a simple UPS device ($80–$150) works for internet-only backup. FTTN/FTTB connections typically stay connected during short outages without any home battery, as the street-side node has its own backup power.