Glossary
Partial backup
Partial backup is the configuration where a solar battery powers only a selected group of essential circuits during an outage (fridge, lights, modem, outlets, sometimes a small air conditioner) instead of the whole house. It is the realistic option for most Florida homes: central AC and an electric water heater draw too much for one or two batteries.
What partial backup is
When the power goes out, a solar system without a battery shuts down too (for safety, so it does not push current into a grid where line workers are on the job). With a battery, the house islands itself from the grid and keeps running. The question is how much of the house. In partial backup, the electrician installs a critical-loads subpanel and moves only the circuits you want protected onto it. The battery feeds that subpanel; the rest stays dark until the grid returns.
Whole-home backup, by contrast, powers everything. It needs more batteries and enough power capacity (kW) to start the central AC, which multiplies the cost.
Why it matters in Florida
Outages here come with hurricanes and can last days, not hours. In that scenario, what matters is endurance: cold food, communication, light and, if possible, one cool room. One or two LFP batteries with partial backup and panels recharging them by day can sustain that indefinitely. Trying to run the whole house drains the battery in a few hours.
Central AC is the problem. A 3- or 4-ton unit draws a lot of power on startup. A small mini-split in one room is the practical solution we recommend when comfort during an outage is the priority.
Common mistake
Buying a battery “to have power during hurricanes” without defining which circuits are included. The salesperson says yes, the electrician installs partial backup with whatever fits, and the homeowner discovers in the first outage that the AC will not turn on. Get the list of backed-up circuits in writing and an estimate of autonomy hours based on real usable capacity. More in hurricane and outage backup.
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