How long does a home battery last in a St. Petersburg outage?

Runtime is arithmetic, not a brochure number. Here is the version we walk through at St. Pete kitchen tables.

Start with usable capacity

A battery's nameplate capacity in kilowatt-hours is not all available. Manufacturers reserve a portion, and continuous power output is capped separately from capacity. Two numbers matter: how much energy is stored, and how much power it can deliver at once.

Then write down your actual loads

Estimate what each backed-up item draws and how many hours a day it runs. A refrigerator cycles rather than running continuously. Internet and lighting are small. Air conditioning is the entire conversation — a central system is usually the single largest load in a Florida house, and a mini-split serving one or two rooms is dramatically cheaper to run.

Divide usable capacity by daily consumption and you have days of runtime with no sun.

Now add the array back in

This is where solar changes the picture. On a clear day the array covers daytime loads and refills the battery for the night. A well-matched system can hold an essentials load indefinitely in fair weather. The hard days are the overcast ones right after a storm passes, which is exactly when you should be conservative.

Loads that quietly drain a battery

• Pool pumps left on a schedule
• Electric water heaters recovering a full tank
• A second refrigerator or a garage freezer nobody remembered
• Well pumps with a hard-starting motor

Put these on managed loads or leave them off the backup panel.

Two batteries versus one

If air conditioning through the night is non-negotiable, plan on more than one unit or accept scheduled cooling. We would rather size honestly up front than have you discover the limit at 2 a.m. in September.

Read more

• Home battery backup in Florida
• Solar battery vs. generator
• Hurricanes and solar panels in Florida
• Roof replacement with solar panels
• Florida net metering

Talk it through with a local crew

Origin is a Tampa Bay solar, roofing, battery and electrical contractor (Florida license EC13012465) working St. Petersburg and the rest of Pinellas County. Start with the quick questionnaire, compare programs on the financing page, or book a consultation — in person, virtual, or a call back.

Nothing here is a guarantee of savings, runtime or approval. Your roof, usage, shade and utility rate decide the outcome.