What a battery backup system involves

A home battery stores electricity, from the grid or from solar panels, and powers part or all of your house when the grid goes down. A complete system has three parts:

  • The battery, rated in kilowatt-hours (kWh) for how much energy it stores
  • An inverter, which turns the battery's DC power into the AC power your home uses (some batteries have one built in)
  • A backup gateway or transfer switch, which disconnects your home from the grid during an outage so the battery can run it safely

Two numbers decide what a battery can do. Capacity (kWh) is how long it can run your loads. Power output (kW) is how much it can run at once, and whether it can handle the surge when a large motor, like a central air conditioner's compressor, starts up. A battery with plenty of stored energy but too little power output can still fail to start your AC.

A typical project runs like this:

  1. Load assessment. The installer reviews your electric bills and asks which circuits you need during an outage.
  2. Design. The system is set up to back up either a short list of essential circuits, often moved to a separate backup panel, or the whole home.
  3. Permits and utility paperwork. Battery systems need local permits, and systems tied to solar also involve your utility, Duke Energy Florida or TECO for most Tampa Bay homes.
  4. Installation, inspection and setup. The equipment install itself is usually quick. Permits and inspections take most of the calendar time.

Tampa Bay considerations

  • Outages here can last days. After Hurricane Milton in October 2024, many Tampa Bay homes were without power for several days. Plan around the outage you're actually worried about, not just a short afternoon blip.
  • Solar alone won't keep the lights on. Most grid-tied solar systems without a battery are required to shut down during an outage, so linemen working on the grid stay safe. A battery set up for backup is what lets solar keep working.
  • With solar, a battery can recharge. A battery paired with solar can recharge every sunny day during a long outage, as long as the system is configured to. Without solar, it only has the charge it held when the power went out.
  • Air conditioning is the big question. Central AC draws a lot of power and drains a battery quickly. Many homeowners back up the refrigerator, lights, internet, fans and medical equipment, and accept limited or no AC. Others size up, add a second battery, or pair the battery with a generator.
  • Placement matters in our climate. Batteries have operating temperature limits, and a hot Florida garage can push past them. In flood-prone areas, mount equipment above expected flood levels. Follow the manufacturer's installation requirements rather than picking the most convenient wall.
  • Check incentives before you sign. The federal residential clean energy tax credit (Section 25D), which used to cover 30% of the cost of a home battery, ended for systems placed in service after 2025. Confirm current federal, state and utility incentives with a tax professional, and make sure your quote isn't based on credits that no longer apply.

What it costs

These ranges come from TampaBayCo's solar and battery cost guide:

  • Battery backup: $10,000–$20,000 per battery unit, with most homes needing one to three units
  • Energy monitoring and load management: $2,000–$6,000 more, depending on how many circuits are monitored
  • For comparison, a whole-home standby generator: $8,000–$18,000 installed

The main things that move the price:

  • Essential circuits or whole home. Backing up everything takes far more capacity than backing up a handful of circuits.
  • Existing solar. Adding a battery to an existing system depends on your inverter. Some systems need extra equipment to charge the battery from the panels.
  • Electrical upgrades. An older or full main panel may need work before a battery can be connected.
  • How long you want backup to last. Each extra unit adds both runtime and circuits, but also adds $10,000–$20,000.

Battery, generator, or both?

A battery gives you instant, silent power with no fuel to store, but its capacity is limited. A standby generator runs on natural gas or propane and can power a whole home for as long as fuel holds out, but it's noisy and needs regular maintenance. For long hurricane outages, many homeowners pair a smaller battery for quiet, instant backup of essentials with a generator for extended coverage. TampaBayCo's generator vs. battery guide walks through the trade-offs.

How to choose a pro

  • Check the license. The work should be done by a Florida-licensed electrical contractor or certified solar contractor; verify the license on the DBPR site (myfloridalicense.com).
  • Get the load list in writing. The proposal should name exactly which circuits are backed up and estimate how long the battery will run them.
  • Ask for both ratings. Get the battery's kWh capacity and its continuous and surge kW output, and ask directly whether it can start your air conditioner.
  • Read the warranty terms. Batteries lose capacity over time. Warranties are usually stated as a number of years or cycles plus a guaranteed capacity at the end, so compare those terms, not just the length.
  • Compare like for like. Quotes are often shown inconsistently, some before incentives and some after. Ask each installer for the gross price.
  • Ask how it behaves in an outage. Confirm whether solar will recharge the battery during an outage and what happens when the battery runs low.

How TampaBayCo works

Tell us about your home and what you want to keep running in the short form above. We send your request to a local energy contractor, who contacts you to review your loads and quote a system. The match is free, and you're under no obligation to hire anyone. Your details only go to the provider matched to your request.