Power Failure Battles: Tesla Powerwall Vs. Generator

Power Failure Battles: Tesla Powerwall Vs. Generator

Whether you want the extra insurance in case of a large-scale emergency or you live in an area prone to frequent outages, you may be like many homeowners, want the functionality that comes with a backup power source. While generators used to be the go-to backup power for homeowners, batteries are now another popular option, one of which is Tesla’s Powerwall. So, which is better?

Tesla’s Powerwall has a far heftier price tag, but once installed, it will not accrue additional fuel costs. The Powerwall can easily handle basic electrical needs and infrequent short outages, but a generator currently remains more reliable if you need power for critical extended periods.

In short, whether the Tesla Powerwall or a generator will better serve your power failure needs depends on many factors, from cost to your personal preference and situation. In this article, you will find a breakdown of the differences between these two power failure systems and the advantages and disadvantages of both. Keep reading to see whether the Powerwall or a generator wins out and why.

Powerwall vs. Generator: What Is the Difference?

Before diving into the ins and outs of whether a Tesla Powerwall or a generator is more suited for power failure needs, look at what exactly the difference is. Both a Tesla Powerwall and a generator are systems that can supply your house with electricity without the use of the grid, but how they each achieve that is quite different.

Tesla Powerwall

This is a battery power storage system. The Tesla Powerwall is a battery that stores electricity. It is meant to be used in most cases with a solar system. When you lose your connection to the grid, the electricity from your solar system goes to the Powerwall for you to access.

  • A Powerwall primarily works by storing excess electricity generated by your solar system.
  • You charge your Powerwall with this energy when you are not experiencing an outage, and then the Powerwall allows you to access this charge when the power fails.
  • This is why a Powerwall works during a power failure, even at times with inadequate sunlight.

A Powerwall can also work without a solar system. In this case, the Powerwall stores electricity from the grid, which you can then access when the grid fails.


A generator is a more traditional form of backup power. Instead of relying on a previously stored charge, generators create electricity when you need it with the use of some sort of fuel.

Generators can run off several types of fuel, including natural gas, diesel, and liquid propane. There are two types of generators you can use in case of a power failure:

  • Backup generators
  • Standby generators

Backup Generatorshave to be manually started and stopped when you need to use them. You can get these in small sizes as well as ones big enough to power a home.

Standby generators require more expert installation. They can sense when the power goes out in your home and will automatically begin running. They also turn themselves on periodically for a few minutes to check for problems and to keep the machinery from becoming damaged from lack of use.

Pricing: Tesla Powerwall vs. Generator

Installing a power failure backup system is not going to be a cheap endeavor, so looking at the price difference in Tesla Powerwalls and generators is vital. There are two areas in which a power outage system will cost you: the upfront cost and the cost to run your system over time.

Upfront Cost

When it comes to the initial cost of installing and getting your power failure system up and running, there is no doubt that the Tesla Powerwall has a larger price tag. Why exactly is that, and how large is the difference? 

How Much Will It Cost to Install a Generator?

A generator capable of running an average-sized home will likely cost somewhere between $3,000 and $6,000. You will also likely need to pay for installation and some other equipment to get everything up and running. You can expect to pay somewhere around $10,000 to get your home equipped with a generator capable of running your home.

Of course, with generators, there is an enormous range of prices depending on the size.

  • You can get a lower wattage generator for under $1,000, but this will not be able to power much of your home.
  • A backup generator will also have a cheaper installation cost than a standby generator.
  • If you get a generator with a large wattage capacity and accrue high extra costs in installation, a generator could end up costing you as much as $18,000. However, this is far from the average.

The $10,000 or less range is what most people can expect to pay.

How Much Will It Cost to Install a Powerwall?

If the generator numbers have you hesitant, then the Tesla Powerwall is sure to scare you. An average home can expect to pay around $20,000 to install a Tesla Powerwall system that will run their home during an outage.

You may be shocked to see this figure, especially considering that a single Tesla Powerwall costs around $8,000. The problem is that a single Powerwall is often not enough to power a home. In most cases, Tesla will recommend two or three to adequately power your home based on the size of your home and average electricity bill.

Another thing to keep in mind is that Tesla has stopped taking orders for their Powerwalls independent of solar system orders. In other words, you can no longer buy just a Tesla Powerwall. You will also need to buy a solar system as well. With the solar system costing around $20,000 itself, this will significantly add to the price.

  • While these numbers may be sobering for some, moving to solar energy will give you a federal tax credit, which currently sits at 26%.
  • Thus the $40,000 for the solar system and Powerwalls will be reduced to $29,600.
  • You also have the potential to benefit from net metering, and you will never have to pay for fuel costs.

These numbers are just estimated to give you a general idea of how much a Tesla Powerwall and the solar system will cost. The exact price will vary depending on the size of your home and your electricity needs.

Outfitting a smaller home will cost less, and you can reduce the price yourself by ordering fewer Powerwalls than Tesla recommends at the cost of some functionality.

Costs to Operate

It may seem like a generator is the clear winner in terms of price, but the upfront cost is not everything in the power failure game. We must also consider how much it will cost to run the system over time.

The Cost of Running a Generator

A generator needs fuel to run, which means you will have to buy fuel throughout its lifetime. The exact cost depends on what fuel you are using, at what rate your generator is consuming the fuel, and what the cost of that fuel currently is. A generator can cost you anywhere from $20 to $200 a day to run due to fuel costs.

Natural gas and gasoline-powered generators have noticeably cheaper fuel costs (less than $100) than diesel or propane-fueled generators. The overall price of your generator will also depend on how much you use it. If you only run your generator for a total of 48 hours the whole year, then you only have to pay the fuel cost for two days of use.

The Cost of Running a Powerwall

This is the area in which the Tesla Powerwall shines. It does not cost anything to use the Tesla Powerwall after it is installed! There are no fuel costs, so the Powerwall does not cost you money every time you use it.

In addition, having the solar system to go with your Powerwall will save you money in the long term on electricity bills. By producing your own electricity, you will no longer have to pay for electricity from the grid. How much money you save will depend on the efficiency of your solar system and the size of your electricity bill, but it is bound to cut costs.

Pricing Takeaway

It does cost substantially more to install a Tesla Powerwall than a generator, but the generator will continue to cost you after installation due to fuel while the Powerwall will not. The cost of running the generator will depend greatly on your choice of fuel and on how often you use it.

The Powerwall thus does have the potential to come out cheaper in the long run, especially if you can significantly reduce your electricity bill with the solar system, but you will have to bite a major initial expense.

Comparing Tesla Powerwall vs. Generator

Pricing is far from the only factor we want to consider when looking at which power system works best as a power failure backup. You also want to look at the following aspects and more:

  • What the system can power
  • How long it will last
  • How reliable it is

Below is a breakdown of the other factors that differentiate a Tesla Powerwall and a generator.

Installation Requirements

Installing something that can power your house is not as simple as hanging it on the wall. There are a lot of technical requirements that have to be met.

A generator has to be able to access the necessary fuel to run and typically needs to be protected from the elements. This means you will be more limited in where you can install a generator and will probably need to also build some sort of covering to protect the generator.

Portable generators, which tend to be smaller in terms of size and capacity, can be located and installed in many more places than a large standby generator.

The Tesla Powerwall, as the name suggests, can be installed on just about any wall. Your installation options are more varied with a Powerwall than with a generator.

Maintenance and Ease of Use

In general, you can expect a generator to be slightly more involved in terms of upkeep than a Tesla Powerwall. For one, you have to ensure that your generator always has an adequate fuel supply.

In some cases, you may also have to manually start and stop your generator yourself, which means also remembering to turn it on occasionally to keep the machinery lubricated.

With today’s technology, both the Tesla Powerwall and a generator can come with a seamless system that powers on and off without input from you, making them both easy to use. You can get a generator that requires more personal know-how, but you can certainly choose to keep things automatic and simple.

What Can It Power?

One of the most important questions when it comes to a backup power system is functioning. How much of your home can a Powerwall or generator run?

To answer this question, we need to look at not only how much power it takes to run something but also how much power it takes to get certain appliances started. Things like refrigerators and well pumps require a surge of power to get going.

In general, generators can power more than a Tesla Powerwall.

  • A Powerwall cannot run anything that requires more than 5 kW to get started, and it can only power things that add up to a total of less than 5 kW.
  • You can offset this limitation somewhat by buying more than one Powerwall.
  • Generators come in varying sizes, so you can get one with much more power than a Powerwall.
  • You can get a generator with 7.5 kW or even 10 kW power.
  • This higher power is often necessary to start up big appliances.

Both the Tesla Powerwall and a generator are capable of running what is termed critical loads. These would be your home’s lights, power outlets, and small appliances. If you need to power larger appliances, especially something critical like a well pump, then a generator may be a more reliable option.

How Long Can It Power Your Home?

The other question to consider is how long your backup power system can supply power to your home. In this case, generators and Tesla Powerwalls are quite different.

Remember that a Powerwall is a battery system. It stores energy. Therefore, it has a limited run time depending on how much energy you have stored. A single Powerwall has a usable capacity of about 13.5 kWh. This means that you can store up to 13.5 kWh of energy to use.

When running on the grid at full capacity, the average home uses around 30kWh per day. At this rate, your Tesla Powerwall does not even have enough energy to power your home for a day!

Before you panic, remember that during a power outage, you will not be running your home at full capacity. You should be using far less than 30 kWh per day, especially because you will not be powering large appliances. Still, most homes require more than one Powerwall for this reason to increase their storage.

In addition, you can still produce energy to charge your Powerwall during a grid failure. If you are using less power and adding energy with your solar panels, then a Powerwall will power your home for much longer. Tesla estimates that a home with solar panels and three Powerwalls can last nine days powering critical loads.

A generator, on the other hand, will power your home as long as you have fuel. What you want to consider is whether you will have access to the fuel source during an outage. A natural disaster might both cut off your power and make it impossible to get fuel. In this case, you will be limited by the amount of fuel you already have.

Determining Which Is Best for You

As you can see, both the Tesla Powerwall and a generator work differently and have various advantages and disadvantages. How does all of this information apply to the average homeowner? Now we will examine what personal factors you should consider in picking between a Powerwall and a generator.

How Frequent and Long Are Your Outages?

Power failures themselves are one of the biggest determinants for whether a Powerwall or a generator will work best. A Powerwall has a much stricter limit in terms of how long it can power your home.

What does this mean?

  • A Powerwall is more suitable for frequent short outages.
  • A generator is more reliable for longer power failures.

A Powerwall works great for outages lasting a few hours or even a day, but if you want power for a week or even a month, a generator is the only way to go.

How Much Electricity Do You Need?

Be aware that you cannot power everything in your home during an outage the same way you would while connected to the grid. If you are content with operating only the critical loads (lights, outlets, and small appliances), a Powerwall will get the job done. However, for larger appliances, a generator may be necessary.

The length of a power outage may also affect what you need to power. You can live without your large appliances for a day, but you may be in trouble if you cannot safely store food in a fridge or access clean water with your water pump for an entire week.

Where Do You Live?

Another thing to consider is where you live. Because a Tesla Powerwall is in conjunction with a solar system, people in sunny areas and with lots of roof space will probably get more out of this system.

However, location can also affect the suitability of a generator. If power outages in your area are frequently caused by storms or other natural disasters, then it may be challenging to get fuel for your generator.

Basically, you want to think about whether your geographical location will have an impact on how easy it is to store and produce energy with your backup system. In most cases, your location will not have a huge impact, but in some cases, it can. Someone living in Florida with frequent storms and lots of sunshine may find a Powerwall to be a smarter investment.

Other Factors

There are additional differences between a Tesla Powerwall and a generator that may affect your personal preference.

  • Noise: A generator tends to make a lot of noise, especially when running at full capacity. A Tesla Powerwall, on the other hand, is a quiet power source.
  • Pollution: Since they use traditional fuel sources like natural gas and gasoline, generators produce pollution. Tesla Powerwalls are a cleaner energy source.

If green energy is important to you, the Powerwall is the clear winner in this area. Solar energy is sustainable and renewable, whereas generators require fuel and cause pollution.

The Verdict: Tesla Powerwall vs. Generator

You have looked at a lot of information regarding the Tesla Powerwall and generators. It can be overwhelming, so now you can break that information down into the major takeaways.

Pros and Cons of a Tesla Powerwall

A Tesla Powerwall is best suited for those who also want a solar system and who experience short and frequent power outages. A Powerwall would not be suitable for those seeking to run large appliances during an outage.

Pros of a Tesla Powerwall:

  • Clean, quiet energy
  • No cost to run

Cons of a Tesla Powerwall

  • High initial cost
  • Limited storage capacity means limited power
  • Cannot handle large appliances

Powerwalls would also be preferable for those who prioritize going green and using environmentally friendly energy sources.

Pros and Cons of a Generator

A generator is the best choice for those who want to spend less to get an emergency power system. It is also ideal for those who might be facing extended outages or who need to run large appliances during an outage.

Pros of a Generator:

  • Cheaper initial cost
  • Can run larger appliances (if you get one with more power)
  • Unlimited power (as long as you have fuel)

Cons of a Generator:

  • Have to pay for fuel
  • Requires fuel to run
  • Noisy and polluting

Generators would be preferable for those who want to stick with conventional methods. If you have had good luck with generators in the past, you may feel like sticking with them.

Can You Combine a Tesla Powerwall and Generator?

You may be wondering if there is a way to circumvent some of the disadvantages of both the Tesla Powerwall and a generator. A generator can be a noisy and expensive option if you have to use it frequently, but a Powerwall will not give you enough power in a long-lasting emergency. Can you get the best of both worlds?

Actually, you can! You can get both a Tesla Powerwall and a generator as a backup power system for your home. This will, of course, cost you a good deal extra, but there are multiple benefits.

  • The Tesla Powerwall can serve as a backup power supply for most small outages.
  • The generator has you covered in case of extended failures or if you need to run a larger appliance.
  • This way, you can be covered in all situations without racking up the fuel cost of a generator.

For people with extensive power needs, a combination of power systems is really the only way. With a Tesla Powerwall and a generator, you are getting energy stored from the grid, from your solar panels, and from the fuel-based generator. This multi-faceted approach will cover just about any of your power needs during a failure. The only downside is the cost.

Can Tesla Powerwall Be Charged by Generator?

Now that you know you can install both a Tesla Powerwall and a generator, you may be wondering if you can charge your Powerwall with a generator. According to Tesla’s website, this is not possible.

  • A Powerwall is installed so that it is integrated with either your solar system or the grid.
  • It would not have access to your generator, and thus you cannot charge it this way.

Because of how a Powerwall is installed, you can only charge it with one source. If you hook it into your solar system, you cannot charge it from the grid nor a generator. The generator can still provide a source of backup power in case the grid fails, and you use up all the energy in your Powerwall, but the generator cannot charge your Powerwall directly.

Bear in mind that in some cases, it is possible to trick your Powerwall into charging with a generator. However, this would require a good deal of know-how and involve messing around with your system. It is a risky option.


Who won the power failure battle? For those who are just interested in emergency power needs, a generator is probably still the best way to go, especially as long as Tesla continues to only sell their Powerwalls with the purchase of a solar system. The Powerwalls are simply more expensive and less reliable currently.

However, if you are interested in solar energy and would also like a power failure option, then a Powerwall is a wonderful option for clean energy during a power failure. Also, if you prefer to invest in new, sleek technologies, you cannot go wrong with the Powerwall.

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The articles here on ThatTeslaChannel.com are created by Greg, a Tesla vehicle and Tesla solar expert with nearly half a decade of hands-on experience. The information on this site is fact-checked and tested in-person to ensure the best possible level of accuracy.

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