Solar and battery backup for home security systems in Perth

Perth's power outages — most common during summer thunderstorms and extreme heat events — are also the times when opportunistic crime tends to rise (dark streets, reduced surveillance). A solar + battery system can keep security infrastructure running during an outage. Here's what you need to know.

How most Perth security systems handle power outages

Standard home security systems (alarm panels, motion sensors, reed switches) typically have their own internal battery backup — usually a sealed lead-acid battery within the alarm panel itself. This internal backup typically lasts:

• 4–8 hours for a standard residential alarm panel (siren, sensors)
• 2–4 hours if the panel is also powering a loud external siren that activates frequently

The limitation: The panel's internal battery is not recharged by your solar panels — it charges only from AC mains. During an extended outage (8+ hours), the panel battery can deplete, leaving the system inactive.

IP cameras (CCTV) typically have no internal backup. They run on 12V or PoE (Power over Ethernet) from a NVR or router. When the power goes out, cameras stop recording unless you have a UPS (uninterruptible power supply) or battery backup for the network equipment.

What a home battery provides for security equipment

A home battery with backup capability (such as a Tesla Powerwall 2, Sungrow SH series with backup module, or similar) can power your security system during a grid outage — for as long as the battery has capacity.

Typical security system power consumption:

• Alarm panel + sensors (standby, no siren): 10–20W
• NVR (network video recorder, 4–8 cameras): 30–60W
• IP cameras (each): 5–15W
• Router/modem: 8–20W
• Total for a typical 8-camera + alarm system: 80–150W

Runtime from a 10kWh battery (9kWh usable):

• Security load only: 9,000Wh ÷ 120W = 75 hours (over 3 days)
• Security + fridge + lights: 9,000Wh ÷ 400W = 22.5 hours

In practice, security systems are a tiny load relative to most batteries. Even during an extended outage, a home battery will keep security equipment running well beyond the typical Perth outage duration (most Perth outages are under 8 hours).

Does your battery support backup (islanding)?

Not all batteries with the same capacity provide backup capability. The key distinction:

Grid-connected only (no backup): Some battery configurations — particularly first-generation or budget setups — do not have a backup circuit. When the grid goes down, the battery and solar disconnect entirely (per AS 4777 anti-islanding requirements). Your security system loses power along with everything else.

Backup-capable (island mode): Batteries with a backup circuit (typically Powerwall 2, Sungrow with EPS module, Goodwe with backup output, Alpha ESS SMILE with backup) can switch to island mode when grid power fails. A dedicated backup circuit — usually in your switchboard — powers selected loads from the battery while the grid is down.

Critical: Only the circuits connected to the backup output remain powered during an outage. If your security system power outlet is on the backup circuit, it stays on. If it's on a non-backup circuit, it goes off regardless of your battery.

Installation requirement: Setting up backup circuits correctly requires an electrician to designate which switchboard circuits are on the backup output. This is done at installation time — discuss it with your installer when specifying the battery.

What backup circuits to prioritise for security

When setting up your battery's backup circuit:

• Security alarm panel and its power supply
• NVR/DVR (camera recorder)
• Router and modem (for remote access to cameras and monitoring during outage)
• One or two IP cameras (most NVRs will run cameras via PoE from their own power)
• Fridge (food preservation during extended outage)

What NOT to include on backup circuits (large loads):

• Air conditioning (draws 1.5–5kW; would drain a 10kWh battery in 2–6 hours)
• Electric oven/cooktop
• Hot water system (unless specifically sized for it)

Wireless security systems and mobile connectivity

Wireless security systems (Alarm.com, Ajax, Ring, Google Nest) have an advantage during power outages: if your router has UPS backup (a small UPS device costs $150–$300), the system can stay connected even if the NBN connection point temporarily loses power.

However: NBN Fixed Wireless and some Fibre-to-the-Node connections may lose internet during a prolonged outage if the local cabinet or wireless tower loses power. Mobile SIM backup (4G/5G) in security panels or cameras maintains connectivity when NBN fails.

If your security system has cellular backup (many commercial-grade alarm panels do), the alarm monitoring centre remains notified even if both power and internet fail simultaneously.

Planning security backup at installation time

For new solar + battery installations: Tell your installer you want the alarm panel, NVR, and router on the backup circuit. This is a standard request and doesn't significantly change the cost.

For existing solar systems with battery retrofit: When adding a battery to an existing system, the backup circuit designation happens at switchboard level. Confirm with your installer which circuits will be on the backup output and verify the alarm panel and camera NVR are included.

For existing solar systems without backup capability: Your inverter/battery combination may not support islanding. Check with your installer — some systems can be retrofitted with a backup module; others cannot.

Solar + battery with backup capability can keep Perth home security systems running for days during a grid outage at minimal impact on battery reserves (security loads are typically 80–150W). The key requirements: a battery with backup/island mode (Powerwall 2, Sungrow EPS, etc.) and the security system's power outlets on the designated backup circuit. Confirm this at installation time — it's not automatic.