5 Best Low THD Generator Models: Portable & Backup - 2023 Picks

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A solid portable generator for your home is considered an essential item in 2023, but they are not all created equally.

You'll want to look for a low THD generator for many day-to-day use cases. And you'll definitely need to know the THD level for a generator if you're planning on using it to power many day to day appliances and sensitive electronics such as cell phones, laptops, and other household items.

Buying one with a high THD level (over 5%) can negatively impact sensitive electronic equipment. Cell phones, laptops, and countless other devices are at risk of permanent damage if used with many of the more powerful generators on the market.

So what should you look for in a home generator, and what are the best portable generators with low THD on the market?

In this short guide we'll run through our 5 best low THD portable generator recommendations.

We also explain the concept of THD and why it's important at the end of this page if you need further context.

Five of the Best Generators with Low THD

Here are five excellent options which come with lower THD and can offer emergency power. 

1. Westinghouse iGen4500

This Westinghouse IGen4500 product is one of several available that are a very low THD generator. It is an affordable inverter generator that produces up to 4,500 watts of surge power. It also runs out of one of two kinds of fuel: natural gasoline or propane. 

It boasts a 3% THD, making it a good choice for sensitive electronics. 

Some of the popular features of the Westinghouse iGen4500Df include low-rated noise production, decent run time before refueling – around 18 hours, and it offers a well-equipped outlet panel. It also comes at an affordable price. It offers:

• Two 20A household outlets

• Built-in USB ports

• Push-button electric start

• 3-year limited warranty

• Lifetime technical support

This range from Westinhouse also has dual fuel options allowing you to use either gas or propane. When you select the version you want to buy, be sure to check the various options as many of them are low THD dual fuel generators.

Check out the impressive iGen4500 here with customer reviews.

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2. Honda EU2200i Companion Inverter Generator

The Honda EU2200i is a small, quiet inverter generator with a rated 1,800 watts of power and 2,200 startup watts. Honda generators are generally thought of as reliable and good value.

The Honda engine features:

• Low noise – 48 dBA

• .95 gallon fuel capacity

• 8.1 operation hours

• 2 AC outlets

• Low oil automatic shut off

• CO sensor and automatic shut off

• CO alarm

It also has less than 3% THD and is one of the bestselling inverter/Low THD models available anywhere.

Check out the Honda EU2200i with customer reviews here.

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3. Westinghouse WGen12000

The Westinghouse WGen12000 is a larger capacity portable generator for the whole house that provides 15,000 peak hours and 12,000 running watts of power.

Westinghouse is known for their low THD generators and this model offers less than 5%, which impressive for its size and power output!

It features:

10.5-gallon gas tank with fuel monitor

• Transfer switch ready L14-30R -14-50R outlets 

• It runs 11 hours on one tank

• Operates larger appliances

• Smart Idle for better fuel efficiency

• Low oil shutdown

• Automatic voltage regulation

• Overload protection

Check out the powerful Westinghouse WGen12000 here with hundreds of customer reviews.

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4. PREDATOR 9500Watt Super Quiet Inverter Generator

The Predator 9500W inverter generator is also a large portable inverter generator effective for the whole house. It offers:

• 459cc engine

• 6.8-gallon fuel tank

• 18.5 hours of running time at 25% load

• Nine total power outlets, including 2 USB outlets

• 7,600 watts

• Electric start

• Low noise level

This unit has less than 3% THD. 

5. Honda EU7000Is

The Honda EU7000IS is a good generator similar to the Predator but with 5,500 running watts. It offers:

• 16 hours of running time

• 389cc engine

• Six power outlets

• Carbon monoxide detection shutoff

Also, like the Predator, it has less than 3% THD

Finding suitable portable generators can be a lifesaver should the power go out and you need to generate electricity.

A home generator provides you with power when you need it like during hurricane season and is on stand by when your electricity is working fine. 

Check out the Honda EU7000iS here + read customer reviews.

How Important are Low THD Generators?

THD stands for total harmonic distortion, meaning it can produce clean power.

The THD level indicates how likely it is that the power generator will cause problems with your high-end equipment, such as:

• Televisions

• Computers

• Game consoles and accessories

• Monitors

• Space heater

• Electric water heater

• Coffee maker

Generally, you don’t have to worry about THD because it is not a problem with utility electricity, but this is a factor to consider with backup power solutions.

Portable generators do not offer the same grade of electricity as utility companies. That means high-end appliances might not recognize the power coming from the unit. 

Why Generator THD is a Concern

THD has been a considerable problem in the portable generator industry for many years.

So much so that brands created low THD power generators specifically to compensate for it. These models are less likely to cause damage to sensitive equipment.

THD levels measure the quality of the electricity coming out of the generators. Lower THD is known as clean electricity. 

What is a Good THD for a Portable Generator?

Typically, for most portable generators a THD level of less than 5% is low.

Anything above 5% may affect the life of your home electrical circuits, cause microprocessors to break down and damage furnace controllers. Look for something under six percent to keep your electronics safe. 

For example the Whisper Series of generators from Firman Power Equipment all have a THD of below 3%.

What Else to Look for in a Portable Generator

There are other things you want to look for in a home or portable generator besides THD level. 

Power Supply, Running Wattage, and Voltage Output

Generators are marketed based on their power output, measured by how many watts they can deliver.

The electricity they supply dictates how many devices and appliances you can operate at once; a normal house will require around 5,000 watts.

If you need to run just some essentials or smaller electronic devices such as cell phones, a coffer maker, or low power lights, know how much power they need.

For example, a power-efficient refrigerator uses about 600 watts. Lights will require anywhere from five to 80 watts for each bulb.

A window air conditioner needs up to 1,000 watts. 

Other use cases such as power tools and powering appliances have their own requirements so be sure to think about what you'll likely need during.

Fuel Type or Power Source

There are a lot of options to choose from here. From gas generators, to propane generators, to those powered by a solar panel. Each of these of course have their own positives and negatives.

Some of the best portable generator models on the market today use a dual fuel or tri fuel setup, giving the owner much more flexibility.

Dual fuel generators will give you two different fueling options, and tri fuel gives you three.

Type of Generator

There are also a variety of low THD generator styles on the market today. You’ll want to understand them to buy the one best suited for your likely needs during a power outage.

Choosing the best portable generator depends on what you think you'll need in an emergency, so try to think about this before it happens!

Home Standby Generators

As the name suggests, standby generators start automatically if the power goes out.

Their power output runs from 5,000 to 20,000 watts and are used to power an entire house. This will be the most powerful generator type you'll find easily.

Portable Generators

The best low THD portable generators tend to be less expensive, but they also have more limited use cases.

These models offer from 3,000 to 8,000 watts of power.

Portable Inverter Generators

Inverter generators are also lower-cost alternatives. They provide 1,500 to 6,500 watts of power as the generator's output.

Portable Power Stations

These are relatively new types of generators – ones that have no motor, so they are very quiet.

They also produce zero emissions, so they are safe to use indoors. They run either on rechargeable battery or solar panels. However, they offer less output, too.

They tend to produce between 1,200 to 3,000 watts of continuous power but of course allow you to avoid the dangers of things like Carbon monoxide poisoning, which is a real risk when using most generators indoors or in an enclosed space. 

Brands to look out for in this category include EcoFlow power stations, Bluetti, and also a new entrant in this market - the E201001 Zero E from Firman.

Portable Generator Safety

Make sure to look over the safety guidelines for the portable generator, too.

For example, look for automatic fuel shutoff, surge protector functionality. Also, most units must run outdoors, so consider weather issues and whether you want a canopy of some kind. 

Depending on which US state you live in, you may also need to use a generator that is CARB (California Air Resource Board) compliant. The CARB emissions regulations don't just apply to California, by the way.