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

Reading Time: 4 minutes

If you live in an area with frequent power outages, you already know the benefits of having backup power installed at 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.

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 savings 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.

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.

By comparison, if you install a battery for backup power, 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 (an average 6-kilowatt solar panel system will cost, on average, $17,760 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.

zip code entry solar calculator

Find out what solar costs in your area in 2020

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 like the Pika Energy Harbor 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 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.

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.

If you’re talking to a contractor about installing a generator, consider getting quotes for solar systems that include batteries on the EnergySage Solar 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.

zip code entry solar calculator

Find out what solar costs in your area in 2020

storage content

15 thoughts on “Battery backup power vs. generators: which is right for you?

  1. Joe- Cruz

    I have considered a Tesla Battery along the Solar panels for my House, when they came over to quote me, they wanted to sell me the Solar panels, only. But in a power outage I needed the Battery Backup, never call again

  2. Luis Herrera

    Yo tengo el sistema sonnen eco 8 y me funciona perfectamente bien. Soy residentes de Puerto Rico que es una isla donde tenemos sol 24/7 y en donde somos impactados tanto por Huracanes como por sismo y en donde el sistema eléctrico colapsa, a sido la mejor obcion para suplir mi hogar con energía renovable.

  3. Gil McCrave

    This is from a report about a study done at Stanford University that was published in April 2019. The title of the report is “Home Batteries Can Sap Your Solar System’s Value”.
    Previous studies estimated the energy output at about nine times the energy invested in solar panels. The new study, which appears in Sustainable Energy & Fuels, however, examined the output from a typical rooftop system installed in five diverse American states. Researchers found that the energy payout ratio ranges from a low of 14 in Alaska to a high of 27 in sunny Arizona—but only when homeowners are able to send surplus power to the grid.
    When homeowners install a battery and charge it with excess electricity before sending leftovers to the grid, however, the energy return on investment for the entire system is 21 percent less than solar panels alone, researchers found.
    When homeowners have no battery and no grid outlet, the system’s return on invested energy falls to seven in Alaska and a high of 14 in Florida—on par with earlier studies. Because homeowners in that scenario need to purchase electricity during the evening, adding a standard lithium-ion home battery improves the energy payback.
    “As far as energy return on investment, it’s difficult to justify adding batteries to residential PV systems as long as excess generation can be made available for other users of the grid,” says Simon Davidsson Kurland, who was a postdoctoral scholar at Stanford’s Global Climate & Energy Project when conducting this research.

  4. EWH

    Thanks Mr. McC.
    Return on investment is not always the top priority. I live in the mountains of western NC, where the power is not reliable. Those that can afford it have a back-up generator. Power loss on the coldest days of the year are not uncommon. Having access to water and more than minimal heat requires electricity and PV/battery storage is close to being competitive with back-up generators. My power bill is less than $50/mo now so convenience would have to be the driving force, I won’t live to see payback for a battery system.

Leave a Reply

Your email address will not be published. Required fields are marked *