Whole-Home Battery Backup: The Bay Area Buyer’s Guide

Between grid issues, wildfire-related shutoffs, and storms, power outages are a simple fact of life for Bay Area homeowners. 

That can make a whole-home battery backup sound like a pretty good solution, especially if it means keeping your lights on and fridge running. But can one battery really power your whole house? How long will it last? And what’s it going to cost you?

We’ll answer these questions and explain everything you need to know about whole-home battery backups below. 

What Is a Whole-Home Battery Backup System?

A whole-home battery backup system stores electricity for your house to use when the power goes out. Unlike a gas-powered generator, it doesn’t need fuel to work. The batteries charge using electricity from the grid, solar panels, or both, depending on how the system is set up. 

When PG&E power goes out, a properly configured system automatically disconnects your home from the grid and switches to battery power. You may barely notice the transition. The catch is that “whole-home” doesn’t necessarily mean it can power every appliance and device in your house. 

Some systems can run nearly everything in your house, while others are designed to keep certain circuits and appliances running. What your battery will power depends on how it’s set up and your home’s electrical demands. 

Why Bay Area Homeowners Consider Battery Backups

Power outages are frustrating enough when they last a couple of hours. When they drag on overnight or longer, working from home, keeping food cold, and maintaining a comfortable indoor temperature can become a real headache. 

Battery backup is becoming more and more appealing for a few reasons, including:

• Wildfire-Related Power Shutoffs: PG&E may temporarily shut off electricity when high winds, dry vegetation, and other conditions create an elevated wildfire risk. This is called a Public Safety Power Shutoff (PSPS).
• Unexpected Outages: Storms, fallen trees, and equipment problems can leave you without power, often with little warning at all. 
• Electricity Costs: California’s average residential electricity rate rose from 32.66 to 33.61 cents per kWh over the past year. Some battery systems can store electricity for use during more expensive peak-rate hours, potentially helping you lower your utility bills. 
• Solar Energy Storage: If you have solar panels, you can store excess electricity generated throughout the day for use later, reducing how much electricity you need to buy from the grid. 

How Much Battery Backup Does Your Home Actually Need?

This is where things can get a little tricky. You start shopping around and see one battery advertised with 13.5 kWh of storage, another with 15 kWh, and maybe a few other numbers thrown into the mix. 

Unless you’re familiar with electrical terminology, it’s hard to know what any of that actually means for your house. The best place to start is with what you actually want to keep running. That’ll steer you in the right direction of the battery size you need. 

Understanding kW vs. kWh

Two numbers you’ll run into quite a bit while comparing batteries are kilowatts (kW) and kilowatt-hours (kWh). They’re easy to mix up, but each one tells you something different about what a battery can do:

• Kilowatts (kW) tell you how much power the battery can deliver at once. If you’re running several appliances at the same time, your system needs enough output to handle them, including the extra power some equipment needs when starting up. 
• Kilowatt-hours (kWh) tell you how much energy the battery can store. This’ll help you figure out how long you’ll have power before the battery needs to recharge. 

Say you have a battery with 15 kWh of usable storage. In theory, it could supply one kW of power for 15 hours or 3 kW for five hours. Real-world backup times will be a little shorter once you account for energy losses and other operating factors, but that’s the gist of it. 

Here’s the part that’s easy to overlook: Having enough stored energy doesn’t necessarily mean you can run everything you want. Your battery might have enough capacity to keep the AC going for several hours, but if it can’t deliver enough power to start the unit, that extra storage won’t do you much good. 

What Can a Whole-Home Battery Run?

A properly sized whole-home battery can handle your everyday essentials like your fridge, lights, internet, and television. If you have a big enough battery, it might even be able to run larger appliances, including your air conditioner. 

But some appliances use a whole lot more electricity than others. Keeping your Wi-Fi router running barely makes a dent compared to powering an electric oven or central AC. 

Here’s a look at how much power common household appliances might draw while running:

These are estimates based on average operating conditions. Actual energy use varies by appliance, efficiency, and usage. 

You probably won’t have every appliance running at once, either, so plan accordingly. A system designed to keep the essentials going overnight will look a lot different from one intended to let you use your home almost normally during a multiday outage. 

And remember, energy use is only one piece of the puzzle. How long you run each appliance will tell you how quickly you’ll burn through your stored energy. 

How Many Batteries Do You Need?

Here’s the million-dollar question: Will one battery do the trick, or are you going to need two, three, or more?

That’ll depend on how much of your house you want to power. To give you a rough idea, here’s how different setups might stack up:

These are just examples, not system recommendations. The actual number of batteries you need will depend on their individual capacities, how much power they can deliver, and how long you want your backup to last. 

If you want to power more than just the basics, it’s a good idea to have a load assessment done. That’ll look at things like your electrical usage, which circuits you want backed up, and how much storage and power output you’ll realistically need. 

How Long Will a Whole-Home Battery Last During an Outage?

The length of time a whole-home battery will power the appliances and devices in your home will vary depending on what you’re asking it to do. 

If your household is drawing an average of 1 kW, that battery could theoretically last 15 hours. Bump that up to 3 kW, and you’re looking at just five hours. 

Here’s the basic calculation:

Battery capacity (kWh) / Average power consumption (kW) = Estimated backup hours

Real-world results will vary. Your battery may lose some energy during conversion, and the system may reserve a portion of its charge. Appliances also cycle on and off, so your household’s electricity use won’t stay constant throughout the day. 

If you’re hoping to get through a multiday outage, you’ll need to think about recharging, too. A battery connected to the grid generally can’t recharge until utility power returns. A properly configured solar-plus-storage system can be a good option here, giving you a better chance of making it through an extended outage. 

Can You Install Whole-Home Battery Backup Without Solar Panels?

In California, battery backup and solar panels are a match made in heaven. But that doesn’t mean you have to pair the two together. 

You can install a home battery backup system without solar panels. The kicker is that if the outage lasts a few days and you run out of stored energy, you’re generally out of luck until the grid power returns. 

Now, you could install multiple batteries, but eventually (if the outage goes on long enough), you’ll be in the same boat. 

Pairing your batteries with solar panels changes things a bit. With the right equipment, your panels can generate electricity during the day, power your home, and recharge your batteries while the grid is down. You can then use that stored energy overnight or when the sun is taking the day off. 

If you already have solar panels, you may be able to add battery storage to your existing system, though compatibility and electrical upgrades will need to be evaluated. 

How Much Does Whole-Home Battery Backup Cost in the Bay Area?

The cost of a whole-home battery depends on the type you choose, among other things. For example, a solar battery typically costs right around $1,037 per kilowatt-hour before any incentives.  

So, if you got a 10 kWh battery, that’d come out to somewhere around $10,500. If you got a 13 kWh battery (which is a pretty average size for residential homes), you’d pay about $13,600. 

What Affects the Cost of Battery Backup Installation?

The batteries themselves account for a significant portion of the price, but there’s more to the installation than hanging a few units on the wall. 

Factors that affect the final quote include:

• Battery Capacity: More storage usually means a higher price, so the more capacity you need, the more you’ll pay. 
• Brand and Equipment: Battery manufacturers differ in storage capacity, power output, warranty coverage, and compatible equipment, so some are pricier than others. 
• Electrical Panel Upgrades: An older electrical panel or one that isn’t compatible with the setup you want may need additional work.
• Installation Complexity: Battery placement, wiring distances, backup controls, and the amount of electrical work required can affect labor costs. The more complicated the installation, the more you’ll pay. 
• Permits and Inspections: Your installation will need to meet applicable electrical and building requirements, which can vary between Bay Area jurisdictions. 

If you’re adding batteries to an existing solar setup, compatibility with that is another thing to think about. Depending on your equipment, you may need additional components or modifications to get everything working together.

Are There California Battery Rebates or Incentives?

There are a handful of rebates and incentives available for select home improvement projects in California. For example, California’s Self-Generation Incentive Program (SGIP) offers financial incentives for qualifying energy storage installations. 

Whether or not you’ll qualify depends on the program category and your circumstances. Certain incentives prioritize lower-income households, and some programs have additional requirements related to wildfire risk or medical needs.

Funding through these programs isn’t endless, either. Incentive budgets can be exhausted, and program requirements change, so before you bank on getting one, check your eligibility and available funding. 

What Should You Look for When Comparing Home Battery Systems?

When you’re shopping for a whole-home battery, there are a few things to pay attention to, including:

• Usable Storage Capacity: Check how much energy you can actually draw from the battery, rather than relying on its total advertised capacity.
• Power Output: Make sure the system can handle the appliances you want running at the same time, including the extra power needed to start the equipment (like central AC).
• Expandability: If you think you’ll need more backup power down the road, look for a system that allows you to add batteries without replacing everything.
• Solar Compatibility: If you already have solar panels, make sure the battery can work with your existing setup. If you think you’ll add solar later, factor that into your decision.
• Warranty Coverage: Look at the warranty period, guaranteed remaining capacity, and any limits on how much energy you can cycle through the battery.
• Safety Certifications: Look for equipment certified to applicable standards, such as UL 9540 for energy storage systems. 
• Monitoring and Controls: Many systems let you check battery levels, track electricity usage, and adjust how much energy you reserve for outages through an app.  

It’s easy to get caught up comparing brands and specifications, but it really comes down to how well the system fits your home. A battery with impressive storage capacity won’t be much help if it won’t work with your electrical or solar setup.

What Are the Best Whole-Home Battery Backup Options?

Tesla Powerwall, FranklinWH, and Enphase are three popular names you’ll likely come across while shopping for home battery backup. All three offer systems designed to store electricity and provide backup power, but they take somewhat different approaches. 

There’s no universal winner. The best fit for your home depends on electrical demand, existing solar equipment (if any), and what you’re hoping to get out of your investment.

What Does Whole-Home Battery Backup Installation Involve?

Installing a whole-home battery backup system takes some planning. Here’s what you can expect when working with an electrician:

1. Home Energy Assessment: Your electrician reviews your electricity usage, existing electrical system, and which appliances you want to keep running during an outage.
2. System Design: Based on your backup goals, we’ll recommend battery capacity, equipment, and a configuration that makes sense for your home. 
3. Electrical Panel Evaluation: Your panel and existing wiring will be checked to determine whether any upgrades or modifications are necessary. 
4. Permits and Approvals: The project may require local electrical permits, inspections, and utility coordination, depending on the installation. 
5. Installation and Testing: Once the equipment is installed, we test the system, including its ability to switch to backup power when the grid goes down.

How long that process will take varies based on the complexity of the installation, whether you need electrical upgrades, and how fast permits and inspections can be completed. 

Is Whole-Home Battery Backup Worth It for Bay Area Homeowners?

Whether a whole-home battery backup is worth it depends on what you’re hoping to get out of it. If you’ve dealt with repeated PG&E outages, work from home, or have medical equipment that needs electricity, having backup power available could be worth the investment. 

The financial side is a little less straightforward. A battery system may help lower your electricity bills by shifting usage away from expensive peak-rate hours, especially when paired with solar. But with installation costs potentially reaching tens of thousands of dollars, those savings won’t necessarily pay for the system anytime soon. 

So, think about how often you lose power, what an outage disrupts in your household, and how much you’re comfortable spending. That’ll give you a better idea of whether a whole-home battery is actually the right fit for your home. 

Whole-Home Battery Backups: Frequently Asked Questions

That was quite a bit of information about whole-home batteries. But if you still have questions, we’ve got you covered. Here are answers to a few of the questions we get most often.

Can one battery power an entire house?

It can, depending on what you’re running. One battery might have no trouble keeping your refrigerator, lights, and a few other essentials going. But if you’re hoping to keep the entire house going, you’ll probably need more than one. 

How long does a whole-home battery last?

That depends on the battery’s storage capacity and how much electricity your household is using. A battery with 15 kWh of usable storage could theoretically last 15 hours if your home averages 1 kW of demand, or five hours at 3 kW. Actual runtime will be a bit shorter due to energy losses and other operating factors.

Can a home battery run central air conditioning?

Yep, provided the system is sized for it. Central AC units can draw quite a bit of power, especially when the compressor first kicks on. Your battery needs enough output to handle the initial demand and enough stored energy to keep the AC running afterward. 

Can you charge an electric vehicle with home battery backup?

With some systems, yes, but you’ll want to be careful about how much energy you’re using. Charging an EV can drain your home batteries surprisingly fast. During an extended outage, that could mean less power available for your refrigerator, lights, and other household essentials. 

Do whole-home batteries require maintenance?

Not much compared to a traditional generator. You won’t have to worry about oil changes or keeping fuel on hand. You’ll still want to follow the maintenance recommendations and have any warning messages checked by a qualified electrician. 

Will my battery automatically turn on when PG&E power goes out?

If your system is set up for automatic backup, yes. It detects the outage, disconnects your home from the grid, and switches to battery power. Depending on the equipment, you might notice a brief interruption before everything comes back on. 

Can I add more batteries later?

Often, yes! Many systems are designed to let you add storage as your needs change. Just keep in mind that expansion depends on the battery model, inverter, and how your system was originally installed. If you think you might want more capacity down the road, bring that up with your electrician before installation. 

Get Your Bay Area Home Ready for the Next Power Outage

You can’t always predict when the power will go out, but you can have a plan for keeping your home running when it does. 

Alpha Omega Electric can help you figure out how much backup power your home needs, compare your options, and install a system that fits your household and budget. If you’re ready to stop sweating (maybe literally) the next outage, contact us to schedule a consultation.

Sources & References

• California Public Utilities Commission – “Self-Generation Incentive Program”
  Explains California’s Self-Generation Incentive Program (SGIP), including energy storage incentives, eligibility requirements, and program funding.
  https://www.cpuc.ca.gov/sgip
• EnergySage – “2026 Cost of Energy Storage in California”
  Provides average residential battery storage installation costs in California, including pricing by system capacity.
  https://www.energysage.com/local-data/energy-storage-cost/ca
• Pacific Gas and Electric Company (PG&E) – “Public Safety Power Shutoffs”
  Explains why PG&E may temporarily shut off electricity during elevated wildfire risk and how Public Safety Power Shutoffs work.
  https://www.pge.com/en/outages-and-safety/safety/community-wildfire-safety-program/public-safety-power-shutoffs.html
• Silicon Valley Power – “Appliance Energy Use Chart”
  Provides estimated electricity consumption for common household appliances, including refrigerators, televisions, lighting, and heating and cooling equipment.
  https://www.siliconvalleypower.com/residents/save-energy/appliance-energy-use-chart
• UL Solutions – “Energy Storage System Testing and Certification”
  Explains energy storage system safety testing and certification, including the UL 9540 standard for energy storage systems and equipment.
  https://www.ul.com/services/energy-storage-system-testing-and-certification
• U.S. Energy Information Administration – “Electric Power Monthly: Table 5.6.A. Average Price of Electricity to Ultimate Customers by End-Use Sector, by State”
  Provides state-level electricity price data for residential, commercial, industrial, and other customer categories.
  https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_5_6_a