A backup battery doesn't have to power your whole house — and for most budgets, it shouldn't try to.
Start with what actually matters during an outage
Refrigeration (fridge and freezer), some lighting, networking equipment, and any medical devices are the near-universal essentials. Beyond that, priorities genuinely vary by household — a well pump is critical if you're on a well and non-essential if you're on municipal water; a sump pump matters enormously if your basement floods and not at all if it doesn't.
More circuits means more battery, proportionally
Every additional circuit added to the backup panel increases the battery capacity (and often the inverter size) needed to support it — there's no free lunch here. Adding central air conditioning to an essential circuit list, for instance, can dramatically increase required battery capacity compared to a lighting-and-refrigeration-only setup, given how much power AC draws.
A tiered approach is common
Many homeowners split circuits into "always backed up" (fridge, some lights, wifi) and "backed up if the battery has spare capacity" (a spare bedroom outlet, a home office). A backup panel with a subset of switchable loads lets you prioritize dynamically during a longer outage rather than committing every circuit to the same fixed allocation.
Check your actual list against real numbers
Once you've decided which circuits matter, add up their actual wattage and typical daily runtime in the battery size calculator, then check against your target outage duration using our duration-based sizing pages. Motor-driven loads need a separate surge check with the surge watts calculator.
Frequently asked questions
Should central air conditioning be on my backup circuit list?
It depends on climate and budget — AC is one of the highest-draw common loads, so including it substantially increases required battery capacity; many households instead prioritize a single window unit or accept going without AC during a typical short outage.
Can I change which circuits are backed up after installation?
Some backup panel configurations allow adjusting which circuits are included, though it typically requires an electrician to modify the physical wiring — it's worth planning your priority list carefully before installation rather than assuming easy changes later.