More and more people are beginning to look into the benefits of switching to a home battery backup system such as Tesla’s Powerwall. A home battery provides the added security and peace of mind of a backup generator without the added hassle of dealing with fuel. Batteries have a lot of advantages: they are cleaner, quieter, more environmentally friendly, and help you save money on your utility. But when push comes to shove, are home batteries as effective as fuel-powered generators?
Well, it depends. There are limits to the ability of a backup battery system to provide a home with power during an outage. For some homeowners, home batteries serve their needs perfectly, but others may run into issues with the limited electrical output of a battery. Whether you can run your home on a battery depends on the battery’s capacity, your home’s energy needs, and the length of time needed for the battery to run.
Weighing the costs and benefits of home batteries and backup generators is not always easy. To determine the best backup energy system for your home, check out our home generator calculator to better understand your energy needs. At AlltimePower®, we are dedicated to bringing you all of the information you need so you can be prepared when the power goes out.
How home batteries work
Home battery backup systems may perform the same basic function as backup generators, but they work in a completely different way. Backup generators require fuel – diesel, natural gas, propane, or gasoline – which they receive either through the preexisting gas lines in your home or separately. This fuel is used to generate electricity, which then powers your home without any assistance from the electrical grid.
Home battery backup systems, on the other hand, connect directly to the power grid. Rather than creating electricity, they store energy from the electrical grid or, in some cases, from solar power. During a power outage, the home battery automatically disconnects from the power grid, creating a self-sustaining, personal grid that powers appliances throughout the home with stored energy.
For a more detailed analysis of the differences between a home battery backup system and a traditional backup generator, check out this blog post.
How long can a house run on a home battery?
One of the key disadvantages of installing a home battery system versus a fuel-powered backup generator is that on average, a home battery will not last as long as a traditional generator. If you live in an area that experiences prolonged power outages, you may want to stick with fuel-powered generators. This may also be a concern if you live in an area prone to natural disasters.
For some homeowners, a home battery system may be all that is needed to secure the home. If you live in an area that experiences frequent but short outages, for example, a batter may be more efficient and easier to maintain. Before you buy a home battery, however, be sure you understand how long it will last in the event of an outage.
How long a home battery lasts depends on the battery’s capacity and the house’s electrical output. Capacity is measured in kilowatt-hours (kWh) and can vary widely from 1 kWh or less to over 10 kWh. The Tesla Powerwall, for example, stores 13.5 kWh. Home batteries on the higher end of the spectrum typically able to last 1 to 2 days, depending on the home’s electrical usage. Of course, reducing your energy usage during an outage will extend the battery life.
Determining your home’s electrical needs
Before you make any decision regarding your home’s power needs, you should first evaluate your home’s electrical output. Understanding how your appliances use energy is the first step toward determining the right kind of backup generator for your home.
Different appliances require different amounts of energy, not just to run, but also to start up. For instance, a refrigerator might require 700 watts to keep it running, but 2,800 watts to start it up. To determine the necessary capacity of a home battery backup system, you should add up the amount of power it takes to start each device in your home.
To extend the life of a home battery during an outage, you may choose to use some appliances less frequently or not at all. While heating and refrigeration may be necessities, perhaps you can hold off on taking hot showers or using the washing machine or dishwasher until the outage ends. Turning off unnecessary appliances may extend the life of your home battery backup system for hours or even days.
How much does a home battery backup system cost?
Regardless of whether a home battery backup system meets electrical needs, the relatively high upfront cost may be a deterrent for some homeowners. For a medium-sized home, a home battery backup system ranges in cost from $10,000 to $20,000, compared with a cost range of $7,000 to $15,000 for fuel-powered generators.
Though the initial cost of a home battery is typically higher than that of a traditional generator, there are other factors that may offset the cost. For instance, after installation, home batteries require little or no maintenance, whereas fuel-powered generators require maintenance and repair costs adding up to about $165 to $485 per year.
Homeowners are also sometimes able to use home batteries to save money on electricity costs. Depending on where you live, the price of utilities may vary based on the time of day and week. To take advantage of this cost variance, simply charge your home battery when the utility prices are low. When prices go up, use the battery system instead of the main grid and watch your utility bill go down.
It’s thus difficult to determine the net cost of installing a backup generator versus a home battery system. For more information about the real cost of a backup generator, check out this blog on the subject.
Solar power and home batteries
Solar power is another way to reduce your utility bill with a home battery system. Some batteries can collect and distribute power not only from the electrical grid, but also from solar panels. This combination of electric and solar power can allow a battery to last much longer than it would on stored power alone. They are also more environmentally-friendly than both fuel-powered backup generators and batteries that rely on power from the electrical grid alone.
Despite the savings on utilities, the higher upfront cost of $20,00 to $40,000 may be too high for some homeowners. And while solar power does help batteries last longer, it is not always reliable. Even on sunny days, solar power alone may not be enough to run all of the appliances in your home. On overcast days, which may be associated with a natural disaster that caused the outage in the first place, power may be further reduced. Nevertheless, they may provide a viable option for those looking for a longer-lasting battery.
Fuel power and home batteries
A third option is using fuel and solar energy to power a home battery. With this system, solar panels, a fuel-powered generator, and the electrical grid all power a battery to create the ultimate protection against outages. This type of home battery can provide the home with energy for weeks or months, or even function entirely off-grid.
These advantages entail a high upfront cost of $30,000 to $50,000 for a medium-sized home, in addition to any installation and repair costs. Some homeowners, however, decide the added security and comfort of being able to indefinitely separate from the power grid is worth the investment. Additionally, some of the cost can be recouped by storing energy when utility prices are low and separating from the grid when prices are high.
Finding the right match for your home
Installing a backup generator or home battery backup system is an important investment. Ideally, it will keep you and your family safe and comfortable during power outages for decades to come. Before deciding which kind of backup system to install, it’s important to understand all of the options and how they will meet your energy needs.
The first step is to determine how much energy your household uses on a daily basis. Calculate the amount of energy you would need to start necessary appliances during an outage. It’s also important to decide how long you would need the power to last: do you live in an area that experiences frequent outages of a short duration, or infrequent outages of a longer duration? Are natural disasters common in your area?
Next, you can begin to take factors such as cost, efficiency, and personal preference into account. Would you prefer to run your generator on fuel, which tends to be most reliable, or are you looking for the cleaner option of a home battery, which is usually more environmentally friendly and easier to maintain?
To learn more about your home’s electrical needs, check out our home backup power calculator. Using this tool, you’ll be able to calculate how much energy you use and how much energy you’ll need from a backup generator or battery in the event of a power outage.