Your numbers
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Your security system
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Backup duration and battery characteristics
Battery & storage
Battery size for security system backup
Check off your security components and set your backup duration. Get a battery size for keeping your home protected through an outage.
How it works
Three steps to sizing your security system
Step 1
Check off your actual security components
Include any recorders or extra lighting, since these often draw more than the alarm panel itself, much like the setup in the internet router backup tool.
Step 2
Set your target duration
A full 24 hours is a reasonable default given how little this small load costs to extend.
Step 3
Combine with other essentials
The critical loads calculator can add this to a broader essentials list.
Understanding security system backup sizing
Why security systems are one of the cheapest loads to back up
A typical security setup, alarm panel, a handful of cameras, door and window sensors, and a keypad, draws around 45 combined watts, figures in line with typical low-power device ratings in ENERGY STAR's product database, making it one of the lowest-power loads covered on this site. Even extending coverage to a full 24 hours or more costs very little additional battery capacity, which is why security system backup is often one of the easiest additions to a critical loads system.
How this relates to the battery already built into most alarm panels
Most residential alarm panels include a small built-in backup battery of their own, typically providing somewhere between 4 and 24 hours of runtime depending on the specific system and how it's configured. A home battery system doesn't replace this built-in battery, it extends coverage well beyond what that limited internal battery alone provides, similar to how the 24 hour backup tool extends coverage for other small loads, a baseline consistent with UL-listed alarm panel standards referenced by Ready.gov's power outage preparedness guidance.
Why cameras and recorders can add up more than expected
While the alarm panel and sensors themselves draw very little, a system with several cameras, especially units with continuous recording, high resolution, or infrared night vision, can add meaningfully to the total load. A network video recorder or DVR storing continuous footage also adds a steady draw on top of the cameras themselves. Checking the actual wattage of your specific camera and recording equipment gives a more accurate total than a generic estimate, the same approach used in the internet router backup tool, and worth combining with the hybrid inverter sizing calculator in our Inverters & Equipment category once totaled alongside other household circuits.
What to do with this number next
Given how small this load typically is, the critical loads calculator is a natural next step to combine security system backup with other essentials into one complete battery size. If financing affects the scope of your backup plan, the quick financing comparison tool in our Financing category gives a fast overview of the cost tradeoffs.
Questions
Frequently asked
A typical security setup with an alarm panel, cameras, sensors, and keypad at 45 combined watts needs only about 1.3 kWh for a full 24 hours, one of the smallest loads on this site.
Most alarm panels include a small built-in backup battery, typically good for 4 to 24 hours depending on the system, which covers short outages without any additional battery needed. A home battery system extends this coverage well beyond what the built-in battery alone provides.
It depends on the number and type of cameras. A single camera draws relatively little power, but a system with several cameras, especially ones with continuous recording or infrared night vision, can add up to more than the alarm panel and sensors combined.
Given how little energy a security system typically uses, adding it to a critical loads panel alongside other essentials costs very little in additional battery capacity while keeping home security functioning during an outage.