Batteries or Generators: Choosing the Best Home Backup Power Solution

Some parts of the world are more susceptible to power outages but no matter where you are it’s never fun when the power suddenly goes out. That’s exactly what happened when Puerto Rico’s beleaguered power grid failed, leading to power outages on New Year’s Eve. Thankfully, there are ways to be prepared for such an occurrence.

There are two main options available when preparing your home in case of a power outage: home batteries and generators. Here, we break down how to choose considering budget, longevity and convenience.

Previously, the only option was fuel-powered standby generators but there are now plenty of different backup power solutions. Quieter, fume-free home battery backups have arrived and are here to stay. Generators can run as long as you have fuel (usually propane, diesel or methane gas — more commonly known as natural gas) to feed them. Batteries come without the carbon monoxide risk, noise or as much of the fuel cost. Solar panels can keep your battery topped off but come with their own price tags.

Batteries and generators provide the same basic service but are considerably different devices. Each have pros and cons so here’s what you need to know when choosing.

Home battery backup systems, such as the Tesla Powerwall or the LGES 10H and 16H Prime, store energy, which you can use to power your house during an outage. Batteries get that electricity from your home solar system or the electrical grid. As a result, they’re much better for the environment than fuel-powered generators. They also might be better for your wallet.

Separately, if you have a time-of-use utility plan, you can use a battery backup system to save money on your electricity bill. Instead of paying high electricity rates during peak use hours, you can use energy from your battery backup to power your home. In off-peak hours, you can use your electricity as normal — but at a cheaper rate — and recharge your battery when it costs less.

If you have solar panels, you’ll be able to store any excess electricity generated by your solar panels. This stored electricity can be used to power your home during the nighttime and periods of panel inefficiency.

Virtual power plants, where you give up a bit of control over your battery’s charge to your utility or another third party, are increasingly available. By giving up some access to the energy stored in your battery, you can earn a bit of money.

On the other hand, standby generators connect to your home’s electrical panel and kick on automatically when the power goes out. Generators run on fuel to keep your electricity on during an outage — typically natural gas, liquid propane or diesel. Other generators have a “dual fuel” feature, meaning that they can run on natural gas or liquid propane.

Certain natural gas and propane generators can connect to your home’s gas line or propane tank so there’s no need to refill them manually. Diesel generators will need to be topped up to keep running.

Battery backup vs. generator: How do they compare?

These pieces of equipment perform the same basic job but come with different costs, maintenance requirements and performance. 

Pricing

In terms of cost, battery backups are the pricier option upfront. Generators need fuel to run, which means that you’ll spend more money over time to maintain a steady fuel supply. 

With battery backups, you’ll need to pay for the backup battery system, as well as installation costs (each of which are in the thousands). Exact pricing will vary based on which battery model you choose and how many of them you need to power your home. It’s common for an average-size home battery backup system to run between $10,000 and $20,000.

For generators, the up-front costs are slightly lower. On average, the price of purchasing and installing a standby generator can range from $7,000 to $15,000. Remember that generators require fuel to run, which will increase your operating expenses. The specific costs will depend on a few factors, including the size of your generator, which type of fuel it uses and the amount of fuel used to run it. You may also need to pay for regular maintenance or inspections of your generator.

Installation

Battery backups earn a slight edge in this category because they can be mounted to the wall or floor, whereas generator installations require a bit more work. Regardless, you’ll need to hire a professional for either type of installation, both of which will require a full day of work and may cost several thousand dollars.

Some home batteries are more like oversized portable power stations and require little more than having an electrician install a transfer switch or smart electrical panel.

Aside from setting up the device itself, installing a generator also requires pouring a concrete slab, connecting the generator to a dedicated fuel source and installing a transfer switch.

Maintenance

Battery backups are the clear winner in this category. They’re quiet, run independently, don’t produce any emissions and don’t require any ongoing maintenance.

On the other hand, generators can be quite noisy and disruptive when they’re in use. They also emit exhaust or fumes, depending on which type of fuel they use to run — which may irritate you or your neighbors.

Keeping your home powered

As far as how long they can keep your home powered, standby generators easily outperform battery backups. As long as you have enough fuel, generators can run continuously for up to three weeks at a time (if necessary).

That’s simply not the case with battery backups. Let’s use the Tesla Powerwall as an example. It has 13.5 kilowatt-hours of storage capacity, which can provide power for a few hours on its own. You can get extra power out of them if they’re part of a solar panel system or if you use multiple batteries in a single system.

Expected lifespan and warranty

In most cases, battery backups come with longer warranties than standby generators. These warranties are measured in different ways.

Over time, battery backup systems lose the ability to hold a charge, much like phones and laptops. For that reason, battery backups include an end-of-warranty capacity rating, which measures how effectively a battery will hold a charge by the end of its warranty period. In Tesla’s case, the company guarantees that the Powerwall battery should retain 70% of its capacity by the end of its 10-year warranty.

Some backup battery manufacturers also offer a “throughput” warranty. This is the number of cycles, hours or energy output (known as “throughput”) that a company guarantees on its battery.

With standby generators, it’s easier to estimate lifespan. Good-quality generators can run for 3,000 hours, as long as they’re well maintained. Therefore, if you run your generator for 150 hours per year, it should last about 20 years.

Which battery backup is right for you?

Across most categories, battery backup systems come out on top. In short, they’re better for the environment, easier to install and cheaper to run long-term. Plus, they have longer warranties than standby generators.

Portable generators can be a good option in some cases. Unlike battery backups, you only need a single generator to restore power in an outage, which brings down the initial costs. Plus, standby generators can last longer than battery backup systems in a single session. As a result, they’ll be a safer bet if the power is out for days at a time.

You might not need that big of a solution if you’re only planning to back up a few things for short periods of time. You can also consider less-permanent solutions such as portable generators and portable power stations if your needs aren’t as intensive.