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Preparing for the Unexpected: Batteries vs. Generators for Power Backup for Homes

Deciding between a battery and a generator for your home's solar power backup supply? Learn what each option has to offer.

Solar power use is on the rise in the U.S. 

According to the Solar Energy Industries Association (SEIA), people installed a new solar energy system every 75 seconds in 2020. Currently, 18.6 million homes use solar power — about 3% of the country’s total energy usage. 

That’s a huge step up from previous years. If this pace continues, we can expect to see approximately 13.6% of homes relying on solar by 2025

When you go solar, you’ll usually need a battery or generator. However, they’re also experiencing a surge in popularity. The COVID-19 pandemic, increased risk of natural disasters and worsening storms due to climate change and an aging electric grid infrastructure have prompted homeowners to explore solar home power systems to keep power on during outages. 

In fact, the SEIA predicts that “[b]y 2025, nearly 25% of all behind-the-meter solar systems will be paired with storage, compared to under 6% in 2020.”

So, what should you look for in a home battery backup system? Your main choices are batteries or generators. 

What Are the Differences Between Batteries and Generators?

In essence, batteries and generators are two main types of backup batteries for home that can power electricity in your home if an outage occurs.


To start, batteries run on electricity. You can charge them from either the excess energy your solar panels produce or energy from the grid. If a battery can use off-grid backup energy, you can recharge it even if the grid goes down — which gives you security in your power sourcing. 

But you can’t recharge all battery power systems during a power outage. If this feature is important to you, check with your contractor to ensure you have the right system.


Although some newer-model generators already use solar energy as power supply, a lot of them typically use a fuel like diesel, liquid propane or natural gas. The fuel then converts to electricity for your home.

As long as you have the correct fuel (and enough of it), your generator will continue to run. But if you were to run out of fuel, some generators can connect to a natural gas line.

However, not everyone has access to a line. If you don’t, consider setting aside extra fuel in your home to prepare for an outage.  

Making the Right Backup Power Decision for Your Home

Because battery power backups and generators have unique advantages and disadvantages, it’s wise to choose which one best fits you, your home and your loved ones. 

Next, let’s look at how a home solar installation combined with a generator or battery can keep you self-sufficient in the wake of an emergency.

[Related: Energy Independence Through Solar]

How Can Solar Power Help Me Prepare for Disasters or Power Outages?

It’s easy to dismiss disaster planning as prepping for unlikely worst-case scenarios. But if we’ve learned anything from the pandemic and increasingly frequent natural disasters, it’s that we never know when or how quickly our lives can change.

Solar home power systems are incredibly useful because grids face many challenges, including car accidents, lightning storms, strong winds, falling trees and even squirrels that wreak havoc on energy lines. 

Because traditional energy providers feed electricity into homes primarily via coal and natural gas plants (which work much differently than solar panels during disasters), they immediately shut down when a crisis occurs. This means homes that rely on their utilities alone can lose power entirely. 

If your power grid or a power plant is damaged during a disaster, the shutdown could last for days. 

Storing backup energy from grids or excess power from home solar energy systems can prepare you for complete power outages. You’ll be able to keep the lights on, prevent food from spoiling, keep medical equipment running and use your laptop for work.

For many people, the appeal of solar power is sustainability. It significantly reduces your carbon footprint and gives you a sense of energy independence. However, a solar panel backup power system will also ensure your safety and help you manage unforeseen circumstances.

[Related: What Is Off-Grid Solar Power?]

Why Choose Solar Batteries?

Overall, battery backups are great for providing instant power for a few hours to keep features that need smaller energy loads, like lighting and refrigerators, up and running. Plus, you can charge an electric vehicle overnight.

To increase your battery’s stored power, you can offset your energy use during peak demand hours if your utility company has a time-of-use plan. This will give you more stored power when the sun goes down — and especially when there’s a power outage. 

Although batteries have an initial higher purchase cost than generators, they can help you save money in the long term. That’s because they run entirely on renewable energy and rarely need maintenance or repair work. 

Per a 2018 GTM report, experts predict an 8% annual decline in the cost of energy storage through 2022. The report notes a likely decline in battery costs as more people adopt independent energy technology in their homes.

Types of Backup Batteries

Lithium Ion

In terms of backup power, lithium ion batteries are the most environmentally friendly option. They have a long life span, maximize power usage, minimize costs and give homeowners more control because they can usually connect to smart home software systems. 

Owners can install lithium ion batteries behind an electrical meter, in a garage or outdoors.

Lead Acid Batteries 

Lead acid batteries are similar to car batteries and are most often used in off-grid solar power systems. Tesla Powerwall batteries still interface with the grid, but the company is developing a battery that works with off-grid systems. Currently, that use will invalidate your warranty.

Battery Options

Tesla Powerwall

Tesla batteries are most effective for people with solar panels already installed at their homes. 

Connecting Tesla’s Powerwall to your electrical system will give you critical power loads for several hours during a power outage. Additionally, it intelligently uses solar energy throughout the day and can lower energy bills in areas with varying energy costs.

If you have critical medical or computer equipment in your home, or if you’d prefer to not rely entirely on the grid, consider Tesla’s Powerwall.

Sonnen Battery

Sonnen’s battery is similar to the Tesla Powerwall in that it’s best paired with solar to store energy for future use. 

It has the advantage of being a plug-and-play solution — installation is easy, so you don’t need an electrician. This option will also help you save on electric bills from its excellent energy optimization. 

LG Resu Battery

LG Energy Solution offers the RESU home battery as a solar storage option that you can combine with another unit for extra backup. You can place it indoors or outdoors. The RESU comes with a 10-year warranty on parts and performance.

AGM Battery

Fullriver’s AGM batteries are premium-sealed, maintenance-free backup power solutions. They can be strung together to create a larger battery storage solution and are often used for off-grid solar systems. AGM batteries have a seven-year warranty.

[Related: Solar and Home Resale Value

Why Choose Generators?  

A backup generator can handle a greater inrush current, so it’s ideal for handling large loads or maintaining power for long periods. However, you need to replace generators about twice as often as lithium ion batteries. Plus, generators make more noise than batteries. 

Generators can keep the lights on, keep the refrigerator running and regulate your home’s temperature. An emergency generator is an excellent choice if you’re near a natural gas line, don’t have a solar power system and need lots of energy for longer periods at home.

Types of Home Backup Generators

Permanent Generators

Fortunately, permanent generators can produce plenty of power during an outage. And compared to portable generators, they’re quieter (but not silent) and larger (about the size of an HVAC unit). Permanent generators require professional installation. 

They’re designed to be waterproof and may include an automatic transfer switch that can restore power remotely.

Fuel-Powered Generators

Fuel-powered generators can connect to your home’s natural gas or propane line. You can refill your gas generator using propane diesel, or gas. A 20-kilowatt model is large enough to cover a full energy load for a home up to 2,500 square feet.

Freedom Solar, your trusted solar panel company often installs this size at residences. About half of our customers choose a gas generator that can be connected through an underground plumbing line, and the other half usually installs a stand-alone propane tank.

Generator Options

As technology advances, generator options are on the rise. Here are some of the most well-known options. 

Kohler Generators

Kohler residential generators are known for their top-notch quality. They’re dual-fuel rated and feature a durable design to withstand harsh conditions. 

They have a range of capacities and can run on gasoline, propane or natural gas. In addition, they can turn on automatically at the first sign of an outage. Kohler generators have a five-year warranty.

Generac Generators

Generac home standby generators and business standby generators offer high-quality, affordable backup power solutions for homes and businesses. These generators run on propane or gas and can provide power for an entire home via three capacity options. 

Generac generators have a seven-year warranty.

[Related: Tips to Save on Energy Costs]

Summary: Differences Between a Home Backup Battery and Generator

Size measurementCapacityPower rating
Environmental impactDepends on charging sourceUses fossil fuels and produces exhaust
Internet connected/controlledYesNo
Activation time following outageNearly instant (no noticeable power loss)10-30 seconds (devices will lose and then regain power)
Installed cost for the equivalent of 20 kW system$28-40K$9-$12K
Eligible for federal tax credit?YesNo
Replacement life span10 years for lithium ion and 5 years for lead acid5 years
MaintenanceNoneReplacement fuel costs or oil change every 1,000 hours (at least once yearly) for line-connected generators
Recommended useEmergency backup, smaller loads, off-gridCritical loads that require a reliable source of large amounts of power

[Related: Are Solar Panels Worth It? What You Need to Know to Decide]

Gain Energy Independence and Prepare for the Worst With Freedom Solar

We have outfitted thousands of home solar installations and businesses with solar solutions. If you’re ready to harness the power of the sun and install a complete solar panel system we’re here to help. When deciding on a battery or generator for your home, remember they must be maintained for proper operation. At Freedom Solar, we can help with your solar repair request. We have a repair and maintenance department for solar panels and Tesla batteries, where they’re happy to help you when needed.

Our socially distanced installations mean we can set up your residential solar power system without entering your home. From consultation to installation, Freedom Solar as a trusted solar power installer can bring solar energy to you while keeping everyone safe. 

Join the solar revolution and contact us today for a free consultation to discuss solar backup generator and backup batteries for homes.

The above article is intended for educational purposes so that homeowners can make informed decisions about their energy needs. Currently, we only install Tesla Powerwalls.