generator vs. battery

Home battery backup power vs. generators: which is right for you?

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If you live in an area with frequent power outages, you already know the benefits of having a backup power supply for your home. Propane, diesel, and natural gas-powered generators have long been the system of choice for homeowners and businesses that want to ensure that the lights stay on when the power goes out in the neighborhood. Now, an increasing number of people are considering newer, cleaner battery options like the Tesla Powerwall.

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Home battery backup power offers many of the same backup power functions as conventional generators but without the need for refueling. Read on for a comparison of battery backup options versus conventional generators, including a review of factors like cost, fuel supply, size, and maintenance.

Key takeaways


  • Battery backup power can be an eco-friendly and cost-effective alternative to a gas generator
  • Upfront costs for backup batteries are high, but lifetime savings can offset the upfront payment
  • Start comparing quotes on the EnergySage Marketplace for maximum saving with solar and storage

Comparing battery backup and generator costs

The exact amount that you’ll pay to install backup power at your home or business depends on the amount of power you need and the equipment you choose. There are many standby generator options available in the $3,000 to $5,000 range that can power a standard American home. By comparison, a home backup battery will start at around $6,000 before installation costs, and in many cases, you’ll require multiple batteries to provide whole-home power. Altogether, you can expect to pay anywhere from $10,000 to $20,000 to install a battery backup system. If you use more energy than your neighbors, you’ll need to buy a bigger generator or more batteries, and you can expect the installation cost to add up to a few thousand dollars to your total price tag.

Home battery backup costs depending on home size 

Compared to generators, battery backups do have a higher upfront cost, and you may need more than one battery depending on the size of your home and your energy needs. For the average medium-sized home, an initial battery backup investment can range from $10,000 to $20,000—this is just an estimate for a small battery system that could supply energy for about a day. If the same medium-sized home is integrating a battery backup system with their solar panel system to generate power, upfront costs can increase to about $20,000 to $40,000.

Savings with battery backup power

The upfront price you pay isn’t the only cost to keep in mind. If you install a generator, you also need to buy the fuel to keep it running. Fuel costs can add up if you frequently rely on your generator – this is especially the case if you also need to pay for the delivery of fuel to your home or business. Not to mention, you need to store the fuel somewhere in your home.

By comparison, if you install a battery for backup power in your home, you can pair it with a solar energy system to charge it with renewable energy from the sun. This will add to your upfront cost (a smaller-than-average 6-kilowatt solar panel system will cost, on average, $16,560 before incentives), but over time it can save you tens of thousands of dollars on your electric bill.

Even without solar, your battery might be able to save you money on your electric bill. Some utilities have time-of-use (TOU) electric rates, which vary throughout the day. If you have TOU rates, a battery can actually result in lower electric bills by providing an alternative source of electricity when rates are high.

Fuel supply for your backup power

The source of energy for your home backup power system is another consideration when you’re comparing your options.

Generators are usually powered by diesel, liquid propane, or natural gas. Your generator can continue to run as long as you have the fuel to supply your generator, and some generators can even be connected to an existing natural gas line. If you don’t have access to a natural gas line, you should expect to refill your generator as needed.

By comparison, a home battery backup system runs on electricity and can be charged either from the grid or from a rooftop solar panel system. If you design a solar plus storage system for off-grid backup power, you can recharge when the grid goes down, adding an extra layer of security for situations where you might be worried about having access to fuel for a generator. (Not all home battery systems can be recharged during power outages, so make sure that your installer knows that this feature is crucial to you.)

Size/power load for backup power options

When you’re comparing your backup power options, think about what you need to keep running when the grid goes down.

If you just want to keep the lights on in a power outage, most batteries will do the job. Many homeowners who choose batteries for backup power are comfortable knowing that “critical loads” like power outlets, lights, and small appliances will be powered in the event of a power outage.

However, not all batteries are capable of quickly discharging enough electricity to get energy-intensive equipment up and running. If your home relies on a sump pump, well pump, or other equipment that uses a lot of power to start up, you’ll need to install a battery that is specifically intended for backup power.

If you install a conventional generator, you won’t have to worry about critical loads. As long as you choose a generator that is sized properly by your installer, you should be able to keep your home or business running without issue, assuming you have adequate fuel onsite.

Operating & maintaining your home backup power system

Generators powered by propane or diesel can be hard to ignore when they’re running. One major advantage of a battery backup system is that it operates quietly and doesn’t burn any fuel, unlike a conventional gas-powered generator. As a result, you don’t have to deal with exhaust fumes or other polluting emissions – a win for the environment and for the air quality around you.

Generators powered by fossil fuels like natural gas or diesel can also have higher maintenance requirements than battery backup options. In addition to refueling, some generators need to be run and tested regularly to ensure that they’ll be operational when you need them most.

The best of both worlds: a generator for battery backup

Looking to get the most out of your battery? Generac just launched their new PWRgenerator (available in Q1 2022) – the first generator of its kind designed specifically to recharge home batteries directly. The PWRgenerator integrates with Generac’s PWRcell batteries to keep them charged in the event of an outage, even when the sun isn’t shining. To learn more about this exciting new technology, check out our article on Generac’s recent product launch.

Before you buy, compare solar & batteries to other generator options

Diesel, propane and natural gas-powered generators are relatively inexpensive and easy to size for your property’s power needs, but there are also benefits to installing battery backup power at your home or business. When paired with solar, you can actually save money on your electric bills, and batteries offer clean, quiet power that you can’t get with a conventional generator.

Home battery backup 2021 product reviews

Overall, the best batteries to consider for your home are options that provide scalability, reliability, and durability. Check out a few of the industry’s leading home batteries, and learn more about each product.

The Tesla Powerwall

The home battery market is currently being led by the Tesla Powerwall. This sleek storage system is easily integratable in any home, and is warrantied for 25 years. It is accompanied by an app that allows you to control your energy usage patterns wirelessly, which can be especially beneficial in places where variable electric rates change the price you pay for electricity depending on the time of day..

Check out our full review of the Tesla Powerwall for more details. 

LG Chem RESU

The LG Chem RESU home battery can be installed attached to the grid or with a solar panel system especially. It boasts a 94.5% round trip efficiency, meaning that 94.5% of it’s stored electricity will be converted into usable energy. Perhaps the best feature of this product is it’s size; it is one of the best on the market in terms of compact installation.

Read our full review of the LG Chem RESU here.

Generac PWRcell

Similar to LG’s home battery, the Generac PWRcell can be hooked up to the grid or to a solar system. The PWRcell’s greatest feature is its ability to provide an instantaneous power surge to appliances at a faster rate than most other home batteries on the market. It’s high power surge  comes in handy when you need to power appliances that need instant and quick power to start up rather than continuous power. This home battery storage solution also comes equipped with an app so all of your battery’s performance metrics, and your savings, are readily available. 

Read our full review of the Generac PWRCell to learn more. 

Panasonic EverVolt Home Battery 

This home battery backup system is compatible with any existing residential solar system, and has a power capacity up to 17.1 kWh. The EverVolt comes in four different variants: two AC-coupled and two DC-coupled modules. Choosing the correct one for you depends on whether you are connecting your battery to a new or existing solar system. This system is also very scalable. Each variant has a modular design allowing it to stack up to 102 kWh of power output to provide electricity to your entire home. The EverVolt features a remote control and online app so you can closely monitor your battery’s performance and energy consumption. 

Read our full review of the Panasonic EverVolt Home battery here for more details.

Frequently asked questions about battery backups for your home 

How long do home battery backups last?

Depending on your energy needs and how conservative you can be with the energy you do have stored, a home battery backup can usually last day or two during an outage. For optimal energy storage and output, you should pair the battery with a solar panel installation to create a closed system that produces and stores energy, and powers your home. 

How much battery backup do I need for my house?

For the average American household that needs power for up to three days while off-grid, a battery bank backup would need to supply over 100 kWh of energy. Again, battery backup needs vary depending on energy usage and other factors. 

How long can a Tesla Powerwall power a home?

Like most home batteries, a Tesla Powerwall won’t be able to power an entire home for more than several hours. However, if you have a solar panel system feeding the Powerwall and a large bank of batteries, you can feasibly power your home for days on stored electricity. 

Start your solar-plus-storage journey today on EnergySage

If you’re talking to a contractor about installing a generator, consider getting quotes for solar systems that include batteries on the EnergySage Marketplace. On EnergySage, you can easily compare your solar options, and see both upfront cost and long-term savings information without even having to pick up the phone. When you join, simply note in your property preferences that you’re looking for a system that includes backup power.

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39 thoughts on “Home battery backup power vs. generators: which is right for you?

  1. Jim Cook

    I would like to back up a single three phase 5KW motor. I have quotes for generators but I am wondering if a battery back up would be more cost-effective for the long run.

    Reply

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