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Single-Phase vs Three-Phase Inverters: What Are They And Which One Do You Need?

Here is a common rule of thumb to help differentiate between single-phase vs three-phase inverters. Residential homes will usually use a single-phase power supply or inverter, while commercial or industrial facilities will use three-phase supplies.

When speaking of inverters, the rule is somewhat the same although they differ depending on the size of the items, or property that you want to power. What happens within a three-phase inverter is that it will convert the DC input from your solar panels into a type of three-phase AC output.

A single-phase solar inverter will convert a DC input into an AC output. If you are curious about the actual difference between the two and how to tell which option is best for you, keep reading.

Single-Phase vs. Three-Phase Inverters

So, the main difference between a single-phase or a three-phase inverter is that a single phase can produce single-phase power from PV modules. It can also connect that to single-phase equipment or a grid itself. A three-phase, however, converts the DC input that solar panels have into a three-phase AC output.

Here’s another way to look at it: for a single-phase power supply, you only need two wires which would normally be called phase and another called neutral. A three-phase power supply will only work when there are at least three wires and that will have to consist of three-conductor wires and a wire that is neutral.

Single and three-phase inverters are essentially units. They are units that electric load distributions will correspond with, and this is a type of phase. A phase is a voltage or current that will exist among a currently used wire as well as a neutral cable as mentioned earlier. A single-phase requires two wires and will essentially have less power.

A three-phase, however, will include three or even four wires. A single-phase will also come within a capacity of less than 5 kW

Johnathan Thurston learns about his solar inverter from an Nectr technician
Nectr Ambassador Johnathan Thurston with electrician Mark Morphatt reading his inverter.

Is A Single-Phase Inverter Better Than A Three-Phase?

Let’s keep one thing in mind here: a single solar phase inverter can only handle so much. There is a specific limit to the type of load that a single-phase inverter can take on. Usually, that number will be 7500 Watts or at least 10 horsepower. That will vary per unit and per area.

You will have to determine the grand total of the wattage of all of your appliances and things that you want to operate so that you will be able to assess whether your single-phase inverter will be able to power them. If it exceeds 7.5kW, you may want to consider a three-phase connexion.

Whether a single-phase or three-phase is better will depend on your purpose for needing one of the units. Keep in mind though, that if you know that your property already has single-phase power, you should make sure that you have a single-phase inverter installed.

One thing that will drive many decisions with this is that if you know you have single-phase power on your property, you may not be able to instal an inverter that spans beyond 5 kW in size. This is because you may not be able to receive a feed-in tariff. The point of this is for any excess electricity that your solar system might generate to be exported into the grid.

You can, however, increase the capacity that your single-phase inverter is able to undertake by applying modifications. Some of these could be adding a DC-coupled battery and using oversized panels that equal up to 10kW.        

What Are The Advantages of a Three-Phase Inverter Over a Single-Phase?

The main advantage that a three-phase inverter has over a single-phase is that it can transmit more power. A poly-phase system itself will produce power at constant rates within a load. The efficiency is also higher than in machinery that might be operated through a single phase.

Additionally, they are also less costly. So let’s take a closer look at the main advantages that a three-phase will have over that of a single-phase. 

  • Higher factors for power and efficiency
  • Higher output
  • The power produced is constant
  • Requires less conductor material

You may be noticing a trend with some of the advantages that a three-phase inverter may have. The unit itself has a higher capacity for an increase in its ability to produce power. The power that a three-phase unit will deliver will be constant, whereas in a single-phase inverter, the power is not always distributed as easily, especially considering a multitude of items that vary in size.

Other than a poly-phase unit producing higher output, they are also more efficient in comparison to single-phase options as these phase options have a limit to what they can efficiently power. The main rule here is to make sure that you are sending the appropriate amounts of power to what you have on your grid.

Also, keep in mind that three-phase inverters have the ability to produce more power for any direct usage. They will also allow you to be able to send more solar energy back into the grid itself compared to that of a single phase.        

What Are the Advantages and Disadvantages Of Using Single-Phase Power?

There are various advantages and disadvantages to using single-phase power and inverters. They all are dependent on what you intend to power. Let’s take a look at some of those benefits and some of the areas where a single-phase option may fall short.  

Some of the Advantages

There are a few notable advantages to keep in mind when it comes to using single-phase power or inverters. Keep in mind that single-phase power will often generate electricity for residential homes as well as power supplies that might be used domestically.

Multiple appliances require a small level of power to be able to operate such as heaters, televisions, and even lights. This is one of the main advantages of using a single-phase inverter. Other advantages will often include the design as well as the operation of the unit itself. It is pretty general, and ordinary, making it easy to maintain and follow.

Most of the units are lightweight as well as compact. Additionally, the current that runs through the electrical lines will often be less whenever the voltage that is being transmitted is high. There are more benefits to utilising single-phase power.

The current is low, which means that this type of power will ensure that the actual unit is able to be operated with an increased efficiency during transmission. It is also best to be used with low horsepower units that don’t surpass 5 HP. Utilising fractional horsepower units is more efficient for this type of unit.   

Some Of The Disadvantages

Let’s take a look at some of the disadvantages of utilising single-phase power. Surprisingly there aren’t too many. You just want to keep a couple of things in mind. Smaller single phase items will need more circuitry options because the supply that single-phase inverters offer may be insufficient for the initial start-up for some things.

You will also notice that some things that require more power or heavier electronic loads will not be able to run with just a single-phase supply or inverter. This goes to show that single-phase inverters may not be able to be used for everything without additional circuitry or modifications to the unit itself.    

Can I Use Either One for the Same Thing?

Did you know that you can actually convert three-phase power into a single-phase? It’s pretty simple to do this, all you need is a neutral wire. Utilising a neutral wire may not be as accurate as other methods that you may come across.

However, using it and completely omitting the other two phases within your three-phase supply line will allow you to convert your system to a single phase.

You can also do the same thing the other way around. You can convert a single-phase power supply into three-phase power by utilising a phase converter. This type of tool can create a third line voltage which will allow three-phase power to exist within a single-phase environment. Isn’t it interesting how you can manipulate electricity?

Considering single-phase vs three-phase inverters, you do want to realise though that phase conversion is possible for different power supplies, when it comes to actual hardware, you still want to be careful when it comes to using the correct types of inverters on the correct type of phase.  

Which Is the Right Option for You?

Here’s one good rule of thumb: if you already have a three-phase supply and you don’t want or even need micro-inverters, then three-phase solar inverters may be the best option for you. If you are still a bit confused about what a three-phase is, this type of inverter takes DC electricity from the solar panels that you have and breaks it down before it sends it out as AC electricity.

This type of electricity will then be shared across the three-phase supply itself. So, think about it this way, you have your solar panels, that DC electricity then moves into your inverter, and then produces three-phase AC. Basically, there is a three-phase AC output.

If you’re still debating, you should know that considering the additional output that you receive, these units are only about $300 more than a single-phase solar inverter, and both units look the same. The only main difference will be the cost, the output, and what it is that you want to be able to power.

Still Wondering?

So if you’re wondering which option is best for you, think about the things that you want to power. If you have items that will require larger loads of electricity such as a sauna, an electric charger for your car, a large air conditioner, or a pool that you want to consistently heat and filtrate, a three-phase solar inverter would be in your best interest.

The main reason why you should consider a three-phase inverter is to significantly reduce or limit your chances of having any issues with voltage and voltage rising. If you are wondering whether or not a single-phase inverter is a better option for you, you should know that single-phase inverters are generally more often used for residential connexions.

This will however depend on the different things that you want to power. It will also depend on whether you plan to power an entire home with larger items that require large loads of electricity, or if you just want to power a few items. To determine which is best for you, figure out what you need power for, and that will help you to gauge your decision in the most appropriate way.

Time To Get What You Need

Now you may have a better idea of whether a single-phase or a three-phase inverter is best for you. Single-phase vs three-phase inverters can be compared based on your specific needs for the units. Always keep in mind what you intend to power, and this should help you gauge your decision.

Remember that electricity can often be converted or modified to allow a single-phase to act as a three-phase and vice versa. For additional information on these units, click here

Next Steps…

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