How to size battery backup for your home in BCS

To size battery backup, you don't power the whole house — you decide which loads must stay on during an outage and for how long, then size the battery to carry exactly those. A small battery running your fridge, Wi-Fi, lights, and a fan lasts far longer than one trying to run central AC, so the conversation starts with priorities, not capacity.

Start with critical loads, not the whole house

List your essentials. Whole-house backup is expensive and rarely needed — most homes only need to keep a handful of things running through an outage. That essentials list is the starting point of the design.

Runtime: how long do your outages last?

Match the battery to the typical duration of your outages. In the BCS summer, cuts can last hours, so we size for a realistic worst case in your area rather than an optimistic average.

Battery + solar = recharge during the day

Unlike a battery alone, paired with solar it recharges during the day — between outages or even within one. That extends your real backup time and carries you through multi-day events, as long as there's sun to recharge.