What is a home battery backup system?

The most common type of home battery backup is a lithium-ion battery, similar to what’s in your phone or electric vehicle (EV). Home battery storage combines multiple lithium-ion cells with power electronics, which regulate the performance of the system and ensure its safety.

There are two options for how your home battery can store energy:

Solar panels

You can pair a home battery with solar panels. The solar panels generate energy during the day to power your home. Typically, any energy that you don’t use will go back to the electric grid, assuming you have a net-metered system. If you don’t participate in net-metering, that energy gets wasted.

With a battery system, however, that extra solar power is stored in the battery for you to use later, such as at night when the solar panels aren’t generating electricity. This is called a solar-plus-storage system.

The grid

You can let your home battery draw and store energy from the grid. You can do this without solar panels. The battery will charge from the grid and hold onto that energy for you.

Put simply, home battery backup gives you options — you can draw energy from the grid or from your battery system. That flexibility leads to battery storage’s biggest benefits.

What are the benefits of a home backup system?

Provide backup during a power outage

Contrary to what many people think, solar panels alone won’t work as emergency power during a grid outage. Unless you’re completely off the grid, your solar system is connected to the power grid. When the grid goes down, those solar systems must be turned off to protect utility workers – sending electricity down transmission lines while crews are working on them would be extremely dangerous.

If your solar panels are connected to battery storage, however, they can stay on and send continuous power to the battery. Even if you don’t have solar panels, you can keep your home running off of your battery while you wait for power to be restored. That means you can keep your lights on, run critical medical devices, maintain your Wi-Fi connection, keep food fresh in the refrigerator, charge your mobile devices, use your kitchen appliances, and open and close your garage door. You can even watch TV if you want.

In short, energy storage batteries provide backup power during a wide variety of events: extreme weather, accidents that affect power lines, and demand response events that require your utility to conserve power.

Energy savings

People considering batteries want to know one thing: can a whole home battery backup save you money?

The short answer is yes, absolutely.

Home battery backup allows you to avoid the highest utility rates, especially if you’re on a time-of-use (TOU) rate or pay demand charges. We'll get more into this later on.

Environmental benefits

Home battery backup can help you lower your carbon footprint by extending how long you can run on renewable power.

If you have solar panels, your batteries store the renewable solar energy that your panels create. You can then use that energy when your panels aren’t generating as much energy, such as when the sun isn't shining at night or in bad weather.

If you charge your battery from the grid, using your battery at times of peak energy demand does more than save you money. To meet all the demand at peak times, utilities have to turn on their oldest, "dirtiest" power plants. These "peaker plants" tend to emit more carbon emissions than other power plants. By drawing power from your battery during peak times, you’re avoiding that carbon-intensive power. You’re also lowering the overall demand curve, reducing the need for peaker plants in the first place.

Easier electrification

As we transition more and more appliances from gas to electric, people raise valid concerns about their power bills and the grid. Will their power bills jump as a result of electrification? Will there be enough power to run everything as we electrify more and more?

Yes, but home battery storage is critical to alleviating these concerns. The bill savings and flexibility gained from battery storage make electrification a more realistic option for many homeowners.

How long can backup batteries power a home?

As power outages from extreme weather events become more frequent, many homeowners are looking for ways to increase their energy resiliency at home, whether that’s through a diesel generator, a solar generator, or home battery backup.

As mentioned above, a battery storage system will allow you to keep using electricity if you lose power. How long that backup protection will last depends on several factors. If you charge your battery from the grid, for instance, you have a finite amount of back-up power. If you have a solar battery backup system, you essentially have an "energy island." Your solar panels continue to generate electricity, which recharges your battery and lets you keep drawing power.

An encouraging study from Lawrence Berkeley National Laboratory and the National Renewable Energy Lab found that single-family homes with solar-plus-storage systems had enough emergency backup to keep critical loads powered throughout a multi-day power outage.

This study makes an important point — it’s unlikely (although possible) that you would have enough battery storage to power your whole house in the event of an outage. However, you can keep the most important appliances running. This is the critical load mentioned in the study. A critical load panel allows you to select and power only the most important appliances during a power outage. For instance, you may want to keep your refrigerator powered but not your pool pump.

Several other factors affect how long you can run on home battery backup. The size of your solar-plus-storage system matters — more generating capacity and more storage mean you have more solar energy for use. The weather also plays a role. If you’re in a temperate climate and don’t need to run your HVAC during an outage, for instance, you’ll be able to conserve more backup energy. If you live in an area with extreme heat or extreme cold and need to power your HVAC, you'll need even more power and your battery won't last as long.

If you want to be able to run your entire home off of battery storage, you have a couple options.

You can stack individual batteries to create more storage capacity in your home. While this is possible, it can get costly.

You can also install a smart electrical panel to optimize your energy use. The smart panel will use real-time performance analytics to automatically ensure that you have the power you need for your priority appliances during an outage.

How much does a whole home battery cost?

The average cost of a home battery system runs from $18 to $23K. Of course, the actual cost of your home battery storage system will depend on several factors, starting with the incentives you take advantage of.

Incentives

There are a number of financial incentives for installing a whole home battery.

• Federal incentives — Under the Inflation Reduction Act (IRA), you can get a tax credit for 30% of the cost of your battery system. The tax credit has no cap.

• State incentives — A number of states offer incentives and rebates in addition to the tax credit through the IRA. For example, the Self-Generation Incentive Program (SGIP) through the California Public Utilities Commission offers rebates for installing battery storage. To see what you may qualify for, check out the Database of State Incentives for Renewables & Efficiency (DSIRE).

When you get a home battery system with Haven, we’ll help you find all the incentives available to you.

Beyond the various financial incentives available, the cost factors break down into two buckets: equipment and installation.

Equipment costs

The cost for a battery itself will range from $9,000 to $11,000, depending on the battery quality you choose. Prepare to pay more for a high-quality battery. The battery chemistry makes a difference, too. Lithium ion batteries come in two main varieties with slightly different chemistries, and therefore slightly different costs. Lastly, the amount of backup power you want affects the cost. More battery capacity means more money, so your power needs will affect the cost.

Installation costs

Equipment makes up around 40-60% of the total cost of a battery system. The rest is covered by installation and that cost will vary depending on the amount of electrical work required. When you choose to get a home battery system from Haven, installation costs are included in your estimate.

Installing battery storage at the same time as a solar system requires a different amount of work than retrofitting an existing system, for instance. Whether or not you install a critical load panel to ensure that the battery power goes to the most important appliances will also make a difference.

Finally, you may or may not need an inverter. Batteries store direct current (DC) energy, but home appliances use alternating current (AC) energy. Your storage system has to convert that energy to make the power output usable. Some systems come with an inverter, while others require a separate purchase.

Can a whole home battery backup save money on power?

Like we mentioned earlier, home battery backup helps you save money by avoiding the highest electric rates. But how does that work, exactly? Let's look at two possible situations: if you have a time-of-use rate, and if you pay a demand charge on your power bill.

Under a TOU rate, the cost for electricity changes depending on the time of day. Electricity costs more at times of peak power demand, such as the early evening when people are coming home from work, turning on lights, and using more appliances. If you have battery storage, you can draw power from your battery system during those times, avoiding the peak electricity prices. When electricity prices fall again (typically overnight and in the middle of the day), you can switch back to drawing power from the grid.

With a demand charge, you pay a charge based on the amount of electricity that you use. Batteries reduce the total amount of energy that you need to draw from the grid, and consequently that you pay for. If you pair batteries with solar panels, you can store the free, renewable energy that your solar panels create, further reducing what you need to draw from the grid.

How do I choose a backup power supply for home use?

So you’ve learned about home battery backup and you’re interested in installing battery storage at home. What’s next?

Decide if home battery storage is right for you

To decide if battery storage is right for you, you’ll want to consider several factors:

• Have you experienced a power outage?

• Are you on a TOU rate or does your energy bill include demand charges?

• Do you get net metering credit if you have solar panels?

If the answer to one or more of those questions is yes, then home battery backup could be a good option for you.

Ready to take the next step? Get a quote from Haven today

Determine the best home battery backup system for you

Next, it’s time to decide whether you want to install a standalone battery system or a solar-plus storage system. There are pros and cons to each — for example, a solar-plus-storage system is more expensive to install but has the benefit of using solar to store free, renewable energy. What's best for you will depend on your unique needs and what you want your system to provide. Haven can help you weigh the options and decide which makes the most sense for your home.

Get multiple quotes and compare your options

Just like when you buy a car, install a new roof, or make any other big financial decision, you want to talk to multiple contractors and compare their quotes. When you’re comparing installers, however, it’s important to look at more than just price. Some other questions to consider:

• Is the contractor certified to install batteries? This is still a relatively new technology for residential customers, so it’s important to make sure your installer has the right credentials.

• How much experience does the contractor have?

• What is the quality and number of batteries in the quote? Do they meet your needs?

• What kind of ratings and reviews has the contractor gotten from previous clients?

It’s a big decision. When you work with Haven, you can know for certain that you’re working with experienced, vetted installers and getting the best option for your exact situation. We’ll be here for you every step of the way.

If you’re interested in learning more about whether home battery storage is right for you, we’re here to help. Get a quote on a home battery system or schedule a call with a Haven representative to ask questions and talk through the process.