What Is a 3-Phase Inverter, and When Should You Use One?

The two main types of inverters are three-phase and single-phase, with three-phase models offering greater power efficiency, larger load capabilities, stable load balancing, and voltage regulation.

Determining which inverter is right for your different applications can be confusing, so we’ve created this guide to answer your lingering questions and help you make the best choice.

Any inverter transforms the circuit of energy. A 3-phase inverter converts the DC power from solar panels or batteries into three-phase AC power. Three-phase AC power is defined by its three separate, alternating currents, each offset by 120º.

Three-phase systems deliver more efficient and balanced power distribution than single-phase power. They’re required when powering industrial equipment, 3-phase motors, and some large appliances.

The nitty-gritty of how three-phase inverters work is complex, but here’s a general breakdown: 

They use advanced electronic circuits to create three separate electricity streams that work together. Tiny computer chips called microprocessors inside the inverters act like conductors to ensure each waveform maintains 120º of separation and starts at a different point in the cycle to create balanced power.

Using pulse modulation, they convert a DC input into three separate AC outputs using something called pulse width modulation, or PWM. This technique encodes analogue data into a single signal, using the proportion of time that a signal is on vs. off to represent varying voltage levels.

Three-phase inverters balance the electrical load across the three phases to minimise any neutral current while incorporating protection from overvoltage, undervoltage, and overcurrent.

Home and business owners may opt for a 3-phase inverter for its many benefits. While this type of inverter won’t work for every application, it offers the following advantages when appropriate:

• Efficiency - Get up to 95% power conversion rates
• Quieter - Less noise and vibrations in the equipment
• Enhanced Power Quality - Less harmonic distortion preserves power quality
• Voltage Regulation - More stability in regulating voltage under varying load conditions
• Longer Lifespan - Last longer because of their smoother power delivery
• Savings - In high-power applications, 3-phase systems can provide the same power from smaller, less expensive components than single-phase systems.

Single-phase and 3-phase inverters differ in several ways, from efficiency and power capacity to grid connection compatibility.

The most apparent difference between these two inverter types in terms of power delivery is the number of waveforms. Three-phase inverters have three synchronised waveforms, while single-phase inverters like those in the EcoFlow Power Ocean (Single-Phase) only have one AC waveform.

As for efficiency, 3-phase inverters can offer around 96-99% efficiency vs. 94-96% efficiency for single-phase models. They can also handle much larger power loads, making them well-suited for commercial or intensive residential applications.

You’ll pay more for a 3-phase system because of its increased performance, improved load capabilities, and sophisticated balancing. Still, it’s a better value for high-power applications because you can handle greater loads more efficiently and with less equipment.

One key determining factor in your choice is your property’s electrical service. If your home has single-phase power, you won’t be able to use a three-phase inverter.

Using a three-phase inverter may make sense or be required in certain circumstances.

If your property is connected to the grid with 3-phase utility connections, you’ll be better off with a three-phase inverter, even though single inverters may be sufficient for essential circuits. 

While this isn’t common for residential properties, industrial and commercial buildings in the UK often have three-phase service. Larger residential properties or new construction homes may also have this kind of electrical infrastructure, but installing it can be costly. Using a 3-phase inverter will seamlessly integrate with the existing electrical distribution system.

Another use case for this kind of inverter is homes or businesses with high power consumption. If your power needs exceed 10-15kW, you may benefit from a three-phase system and an extensive storage system like the EcoFlow Home Battery. It may be due to multiple large appliances that run simultaneously, industrial processes, or data centres.

Machines and motors designed for three-phase operation, such as industrial pumps or compressors, will require a 3-phase inverter. Other examples of three-phase power equipment include commercial HVAC systems, manufacturing equipment, and elevators.

High-power solar systems with wattage beyond 25kW will benefit from the efficiency of 3-phase inverters. Not only do they connect to the grid better than commercial solar, but they also improve the quality of power sent into the grid. 

It will put less stress on your equipment and allow it to work longer. Systems like the EcoFlow PowerOcean (Three-phase) home solar battery solution use a three-phase inverter to convert DC power from your solar panels into AC power to keep your home running.

You can retrofit a three-phase inverter, but it will depend on the correct electrical infrastructure. To integrate the inverter seamlessly, you may need to upgrade wiring and panels or modify your utility service. Professional evaluation and installation may be necessary.

If you have three-phase utility power, you will likely want a 3-phase inverter, but single-phase inverters may still be sufficient to power essential circuits. You’ll only need the upgraded inverter if the equipment you’re backing up is three-phase.

The primary benefits of the three-phase inverter model are its high efficiency, ample power capacity, and compatibility with commercial and industrial equipment. Check your utility service and the equipment you want to back up to see if they are 3-phase.

If you want to move forward with a three-phase inverter, consider getting a professional assessment to determine your needs. Demanding power applications deserve high-capacity battery storage solutions, like the EcoFlow PowerOcean Three-phase, which features a built-in three-phase converter.