Is 3-phase power better for solar?

26 Aug.,2024

 

Do You Need a 3 Phase Solar Inverter? - Airis Energy Solutions

Decisions, decisions. You&#;re reading this because you&#;ve done some extensive research into solar power, but there are a few more answers you need before proceeding with your venture. Before we can answer the question about 3-phase solar inverters, it makes sense to review the two main power delivery types upon which your power supply is based.

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From there, we can consider the type of solar power inverter to employ and whether you need a battery inverter charger. It all depends on your use case. 

 

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Before You Get a

3-Phase Solar Inverter

: Check if You Have a Single-Phase vs. Three-Phase Power Supply

Deciding between a single-phase or three-phase power supply is one of the easiest and most basic determinations to make when installing a building&#;s electrical system. The main factor is the total electrical load the system is expected to draw.

Average residential homes and small businesses (think stores, three or four-room offices) need only a two-wire (one conducting, one neutral), single-phase power supply for running heating and air conditioners, plus various appliances and lights. 

Many mid-sized businesses, large housing developments, and industrial units are better served with a four-wire (three conducting, one neutral), three-phase power supply. It can better accommodate higher loads, such as driving powerful electric motors and pumps.

 

Advantage of Three-Phase Power Over Single-Phase

Since a three-phase power supply can extract three times as much current from the electrical grid, it can transmit three times more power to the structure than a single-phase power supply. Another reason three-phase is better for industrial use is the consistency of power delivery. Single-phase is more susceptible to voltage rise and dips, whereas three-phase delivers power at a steady, constant rate.

 

Accordingly, most industrial buildings are three-phase, whereas small commercial units can make do with a less expensive and simpler single-phase system.

 

Want to See if Your Building Has Single or Three-Phase Power Supply?

Have a look at your switchboard, being careful not to touch anything. Count the poles on the levers labeled Main Switch. If there is one lever, you have a single phase. If there are three levers (usually labeled 1, 2, 3), you have a three-phase power supply.

 

Deciding Between a Single and

3-Phase Solar Inverter

Single-Phase Solar Inverter

Logically, you might assume that if you have a three-phase power supply, you would need a three-phase solar inverter for your solar panel system. However, even if you have 3-phase solar power, a single-phase inverter may be enough.

Single-phase solar inverters are simpler and cheaper than three-phase solar inverters. This simplicity makes them ideal for connection to a single-phase power supply, but you can also connect them to one phase of a three-phase system. 

So, if the solar system installed in your building is three-phase, the inverter will only work on one-third of the system. The solar energy power from the other two phases could be sold back to the grid.

An issue with single-phase inverters when feeding power back into the grid is voltage rise. On a day with good solar power generation and low demand in your building, it&#;s possible that your solar panel system might send too much voltage into the grid. 

If that&#;s the case, the inverter will likely trip to protect itself, shutting off entirely. A three-phase inverter will help alleviate that problem by spreading the load more evenly.

A single-phase solar inverter would not be appropriate for an off-grid 3-phase solar power system with a battery bank because the power from the other two phases would be wasted.

 

 

3-Phase Solar Inverter

A 3-phase solar system is designed to meet greater electrical demand; thus, using a 3-phase solar inverter makes sense when attached to a 3-phase electrical system.

Are you interested in learning more about 3phase solar? Contact us today to secure an expert consultation!

In the case of an on-grid solar system, a 3-phase solar system design can send more power back into the grid. 3-phase inverters also reduce the risk of voltage rise by sending solar power to the grid via three cables instead of just one, thus spreading the load.

In addition to the increased power delivery potential, three-phase solar inverters are better at delivering power evenly to different areas of the structure. More power on tap generally equals more stable energy. Acting as inverter chargers, they can also deliver more consistent power to charge the solar battery bank.

Finally, 3-phase inverters are the most appropriate choice for off-grid 3-phase solar power systems. They allow the full potential of the solar system to be harnessed.

 

Making the Right Choice in Solar Inverters


As we&#;ve seen, there are many factors to consider when deciding between inverter types, brands, and capacities. Some examples of popular inverters are the Fronius Symo 3.0 and SMA Sunny Tripower. They are both good representatives of a three-phase battery inverter charger. 

Smaller home solar systems are usually well served by a single-phase inverter. Still, larger 5KW solar systems and up are better served by a 3-phase solar inverter to take advantage of all the benefits discussed above.

 

Single or

3-Phase Solar Inverter

for Your Property? We&#;ll Find the Right One

At Airis, we make installing a solar power system completely seamless. If you want to take a hands-off approach, our team can size the system appropriately for your needs. Alternatively, if you want to be fully involved in the decision-making process, we&#;ll be happy to educate you on the different aspects of your solar power system.

Book your free on-site consultation today to find out how large your solar power system can be, what type of inverter is best for your needs, and more.

Solar power and single-phase vs 3-phase power connections

Depending on where you live, your home may be fed by single-phase or 3-phase electrical connection. What relevance does this have for your solar PV installation?

 3-phase and single-phase power

Both single-phase and 3-phase electricity are used to transmit and distribute electricity. Depending on where you live and how much electricity you consume, your home will be fitted out with either a single-phase grid connection or a 3-phase solar grid connection. (Most homes have single-phase connections.)

Regardless of whether you have a single-phase or 3-phase connection, the appliances in your home all (almost certainly) run on a single phase. (3-phase power is used to power motors in certain industrial applications, but not in homes.) In the case that you have a single-phase connection, electricity flows in and out of your home through a single phase (imagine a single cable/circuit).

If you have a 3-phase solar inverter connection, on the other hand, the electricity entering your home is divided into three separate phases (imagine three cables/circuits). Different devices in your home will be powered by these different phases. For example, your lights may run on one phase, while your washing machine and refrigerator may be on the other two phases.

The image below, from Prolux Electrical, illustrates how 3-phase power is &#;divided up&#; for household & industrial loads. You can see that all three phases feed into the industrial motor, while the light globe and power point are each serviced by a single phase (represented by the yellow and red lines, respectively).

Illustration of how 3-phase power works on types of electrical loads. (Image via Prolux Electrical.)

What the number of phases mean for your solar PV system?

If you don&#;t have a solar PV system, you may very well have no idea if you&#;re on a single-phase or 3 phase solar inverter connection. Regardless of which one you have, the electricity you use is most likely being delivered seamlessly to all of your appliances &#; so it&#;s not really anything to be concerned about.

In the event that you want to install a solar PV system, however, phases matter. For a single-phase connection, a single-phase solar inverter should be installed &#; fairly straightforward.

For a 3-phase connection, on the other hand, there are a number of options. In most cases the best and simplest option is to get a 3-phase inverter, which will distribute the solar power evenly across all three phases.

Another option for a 3-phase connection is to install one single-phase inverter on one of the phases in the home (preferably the one that uses the most electricity/has the heaviest loads). The downsides of this approach are that 1) if the solar system is too large, the inverter could &#;trip out&#; if the voltage for that phase goes to high, and 2) the solar energy may not flow to the phase where it is needed most. For this reason, with this approach it&#;s important to have your solar installer undertake an assessment to determine which phase is the best one &#; if you install on the wrong phase, the energy that your solar system generates could end up going to waste.

The third option is to install multiple (up to three) single-phase inverters, each one on its own phase. This could prove to be a more expensive option than simply using a 3-phase solar inverter, however, so it&#;s important to consult with several solar installers to collect a variety of quotes and opinions before making a decision.

Solar system size considerations

It&#;s also important to check whether your phase connection will have an impact on the size of solar system that you&#;re allowed to install. Generally speaking, tighter solar system size limits are placed on homes with single-phase connections than those with 3-phase connections.

In South Australia, for example, solar PV system size is limited to 10kW in buildings serviced by single-phase connections, whereas homes and businesses with a 3-phase connection may install systems as large as 30kW. Generally speaking, this is why a requirement for special approval from utilities for grid-connection of large solar PV systems in remote areas (which are sometimes serviced by &#;single wire earth return&#; or SWER lines) is more common than in areas with high population densities.

AC vs DC electricity explainer (just in case)

AC (alternating current) electricity. AC electricity is what most household electrical appliances require to operate. The other type of electricity, DC (direct current), is what solar panels and batteries produce. DC electricity is converted to usable AC electricity through a device called an inverter. AC current is distinguished from DC current primarily by the fact that its direction &#;switches&#; back and forth rapidly, whereas DC is uni-directional. Without getting into the technical details as to why, this property makes AC electricity more suitable for long-distance transmission.

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Top image via Wikipedia

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