What Size Home Battery Do I Need for a 2,000 Sq Ft SoCal House?

Square footage is one of the weakest predictors of battery size. What actually matters is how many kilowatt-hours (kWh) your home uses, how much of that lands in the expensive late-afternoon and evening hours, and which circuits you want running when the power goes out. Two 2,000 square foot houses in the same Southern California neighborhood can need very different systems if one has a pool pump, EV charging and central air and the other does not. Apollo Home Power installs LiFePO4 battery modules rated at 14.3 kWh each, so a typical project is two batteries (28.6 kWh) or three batteries (42.9 kWh) \u2014 roughly about three times the size of a Tesla Powerwall.

Why square footage is the wrong starting point

A battery stores energy. It does not care how many rooms it is powering. What drives the right size is:

• Your actual kWh usage, which is printed on every utility bill.
• When you use it. Southern California time-of-use rates make the late-afternoon and evening window the expensive one, so the energy you pull then is what a battery is trying to replace.
• What you want backed up. A system sized to keep a refrigerator, lights, internet and a few outlets alive is different from one meant to run central air conditioning.
• How long you want it to last. A short rolling outage and a multi-day Public Safety Power Shutoff are different problems.

Two homes of identical size with different appliances, occupancy and habits will land on different answers. That is normal.

How to estimate your own number in about ten minutes

1. Pull 12 months of utility bills. Look at your monthly kWh, not just the dollar amount. Note your highest month (usually late summer in inland Southern California) and your average month.
2. Divide the monthly kWh by the number of days to get a rough daily figure.
3. Estimate the evening share. Most households concentrate a meaningful chunk of daily use into the late-afternoon-to-evening peak window \u2014 cooking, air conditioning, laundry, TVs, EV charging. That evening slice is the portion a battery is realistically shifting each day.
4. List your must-run loads for an outage. Refrigerator, a freezer, Wi-Fi router, a few lights, phone and medical device charging, and possibly a well pump or a window AC unit.
5. Decide on duration. One evening of peak coverage is a very different target from three days of essential-load backup.

If that sounds like a lot of arithmetic, it is exactly what a proper in-home energy assessment is for. The installer should be reading your bills and your panel, not guessing from your floor plan.

Backup capacity vs. backup output \u2014 the part people miss

Kilowatt-hours are the fuel tank. There is a second number that matters just as much: how much power the system can deliver at once, and which circuits it feeds.

Apollo Home Power's battery systems provide backup through a dedicated backup panel rather than carrying an entire 200A home. Backup output is approximately 33A, which covers roughly six to eight critical circuits. Depending on your usage, the battery's charge level and which loads were selected for backup, the system can power those backup loads for roughly one to three days; the monitoring team can give a more specific estimate based on your real usage.

Two practical consequences for a 2,000 square foot house:

• Only what is wired to the backup panel runs during an outage. If you want to know which circuits those are, go to the backup panel and shut it off \u2014 anything that loses power is on it.
• Large, rarely used appliances are usually better left off the backup circuits. Adding them increases battery draw and shortens how long the system can carry you through an outage.

How the battery actually saves money in Southern California

Apollo Home Power's SGIP battery systems are grid-tied, non-export systems \u2014 they are not connected to a home's solar by default and do not send power back to the grid. The batteries charge from the grid during cheap overnight hours and discharge during the expensive late-afternoon-to-evening peak window. A commonly used programmed schedule is charge 12:00am\u20135:00am, standby 5:00am\u20134:00pm, discharge 4:00pm\u20139:00pm, and standby 9:00pm\u201312:00am. SGIP also requires a time-of-use rate, and Apollo's SGIP department handles the rate switch.

If you already own solar outright, the battery can still work in parallel: it charges off-peak while your panels produce, and the two operate independently. Connecting a battery directly to an existing solar array is a separate service with its own requirements, and it can only be considered after the SGIP project is finalized and the homeowner proves they own the solar system.

Where the battery goes on a typical SoCal lot

Placement affects what you can install as much as capacity does. Batteries are most commonly installed outside the house or garage, and some authorities having jurisdiction do not allow batteries in the garage at all. If batteries are installed in a garage, code requires a heat detector in the garage connected to a smoke detector inside the house. Apollo Home Power recommends keeping batteries in the originally approved outdoor location, since the system is designed and permitted for outdoor installation, which aligns with California fire codes and avoids redesign delays. For HOA architectural committees, the company can send schematics and dimensions.

About Apollo Home Power

Apollo Home Power LLC serves California homeowners with home battery backup and works through a vetted network of installers rather than its own crews, matching homeowners to installers based on project requirements, preferences and location. Service areas referenced for technician coverage include San Diego, Menifee, Lancaster, Newbury Park, Hemet, the High Desert (Victorville, Hesperia, Apple Valley, Adelanto, Helendale, Barstow, Phelan) and Inland Empire cities such as Rancho Cucamonga and Fontana.

Why that matters for a sizing question:

• The equipment is modular. Each battery is 14.3 kWh, so two total 28.6 kWh and three total 42.9 kWh. The chemistry is LiFePO4, which the company describes as safer, more stable and non-combustible compared with lithium-ion.
• Sizing starts with a real assessment. The process includes a quick eligibility check, an in-home energy assessment, installation and setup, and ongoing customer care. The site survey itself takes about 15\u201320 minutes and includes a 360\u00b0 perimeter LiDAR scan, photos of the electrical panel and sub-panels, and garage interior photos. Engineering then reviews those photos and confirms the battery location with the homeowner 1\u20132 weeks later, before permitting.
• Cost is handled through rebates. Apollo Home Power handles SGIP rebate applications and demand response enrollment, and helps families install systems using California's Self-Generation Incentive Program and other state and federal rebates. For SGIP-covered projects, the batteries, inverter and labor are covered by the rebate assigned to the developer, so the homeowner's total cost is $0 with nothing out of pocket or upfront. The company states it will notify the customer ahead of time if anything changes or if an item would not be covered. Eligibility rules vary \u2014 for example, the SGIP Equity Resiliency Budget requires the home to be in a high fire zone and on medical baseline \u2014 so check current program requirements for your address.
• After install, the system is watched. Apollo Home Power offers real-time system monitoring and support, and manages the project lifecycle from consultation and design through procurement, installation and post-installation support.
• Quotes are quick. The company states customers receive an accurate quote within 3\u20135 days after filling out the website form.

Next step

Before you commit to a number, get your last 12 utility bills in one place and have someone look at your panel. If you want a sizing recommendation specific to your Southern California home, including whether an SGIP-covered system applies to your address, start at https://www.apollohomepower.com or call (858) 923-5401.