What is a 3-Phase Solar System and do I need one?

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If you’re deep into your research around home solar systems, then there’s a good chance you’ve stumbled across the term ‘three-phase power’ or ‘three-phase solar’.

Often touted for its higher capacity, three-phase solar may seem like the perfect fit on face value. But there are some limitations to this type of solar connection, particularly if you are looking to install solar at a residential property.

To help you distinguish which type of solar system would be best suited to your property then, we’ve broken down the basics of three-phase power and highlighted the key factors to this connection type. From how it works, to the pros and cons and what you can expect to pay, find out if you should consider a three-phase solar system with this Canstar Blue guide.

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What is a three-phase power supply?

In order to comprehend what a three-phase solar system is, you’ll first need to understand three-phase power supplies. The power supply is the connection point that your home has to the grid and it generally comes in two forms; single and three-phase. Three-phase, as the name suggests, uses three active wires and one neutral to transmit electricity from the grid to your appliances and the like. Single-phase only uses one active and one neutral wire.

Single-phase power supplies are most common among residential properties in Australia, with three-phase being reserved for larger homes and commercial properties. However, you may find some older homes will have a three-phase power supply.

What’s the difference between three-phase and single-phase power supplies?

Power board with four power cords sitting around it

The main difference between a single-phase and three-phase power supply is the number of wires used to transmit electricity from the grid to a property. As the names suggest, a single-phase connection will use just one live wire, whereas three-phase incorporates three active wires.

A three-phase power supply is generally better equipped to handle bigger energy loads as it has the capacity to draw more power from the grid due to the additional wires. This is why this connection type is more common in commercial properties that tend to consume energy at a higher capacity. Three-phase power however, can be useful for homes that operate large appliances such as heaters, pool pumps, spas or electric vehicle chargers.

With a three-phase power supply, electricity distribution is essentially divided among the three wires, meaning that certain appliances may only be powered by certain wires. For example, your dishwasher and washing machine may be powered by one supply while your home appliances run on another. On a single-phase connection, all household power is supplied through the single wire.

How do I know if I have a three-phase power supply?

If you are not sure what power supply your home runs on, you should be able to find this information on your electricity meter. On the meter, it should state whether you have ‘1-phase’ or ‘3-phase’ power. You can also check the number of breakers you have on your fuse box under the ‘main switch’ tab – if you have just the one, you’ll likely have single-phase power. Keep in mind however, that your switchboard is live with power. To stay safe then, it is best to avoid touching the board where you can.

If you can’t find this information written on your meter or you are struggling to decipher the electrical jargon, you can also contact your energy distributor and they can tell you what power connection your home has.

How does a 3-phase solar system work?

Three-phase solar systems run on a similar principle to three-phase power, in that the system sends electricity across three wires, as opposed to one. In doing so, these systems can minimise the risk of voltage issues and triple the solar power supply being sent to appliances (or the grid), allowing the system to run at a higher efficiency and capacity.

A three-phase solar system operates in the same sense as an ordinary solar panel system, however, instead of a single phase solar inverter, you’ll need to incorporate a three-phase inverter. You’ll still be able to install standard solar photovoltaic (PV) panels as part of a three-phase solar system though – it is simply the inverter type that changes.

3 Phase Solar Diagram

To help you wrap your head around how a three-phase system works, we have included a 3-phase solar system wiring diagram below.

Diagram of how a 3-phase solar system works by Canstar Blue

Do I need 3-Phase Solar?

Whether you should install a three-phase solar system will depend on the type of power supply your property has. If you have a single-phase power supply, you will need to install a single-phase solar inverter and system. This is because a single-phase power connection cannot absorb and transmit power from three different supply points.

If you have a three-phase power supply, however, you do have the option to install either single or three-phase solar. Typically, three-phase power supply is separated across three mains, which means that certain appliances will only be powered by certain wires. As a result of this, there is the option to install a single-phase inverter on just one power supply and having only the appliances on that connection run on solar. Excess solar from this supply however, can still be diverted to the other two connections through the use of a bi-directional meter (which is generally installed with your solar), before being sent to the grid in exchange for a solar feed-in tariff (FiT).

It should also be noted that installing a single-phase solar inverter on a three-phase power supply could impact the voltage on your system. This is due to single-phase inverters having a lower capacity than three-phase connections, meaning it has to work much harder to transmit the solar power to be used. As a result, a single-phase inverter may trip more frequently than it would if it were three-phase.

Solar Plans & Prices

Here are some solar-specific energy deals available in New South Wales, Victoria, Queensland and South Australia. These are plans that are marketed towards customers with solar panels and typically offer a higher feed-in tariff than standard market offers. Be sure to read the fine print and double check the base rates on these offers before making a purchase decision.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Ausgrid network in Sydney but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 3900kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Citipower network in Melbourne but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on the Energex network in Brisbane but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4600kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

Here are some of the cheapest solar-specific deals from the retailers on our database. These costs are based on SA Power network in Adelaide but prices will vary depending on your circumstances. We show one product per retailer, listed in order of lowest price first. Annual price estimates assume general energy usage of 4000kWh/year for a residential customer on a single rate tariff. Price estimates exclude solar feed-in tariff credits. These are products from referral partners†. Our database may not cover all deals in your area, and please check retailer websites for up to date information.

What are the pros and cons of 3-phase solar power?

There can be an argument made for both purchasing and not purchasing a three-phase inverter and system.

Pros Cons
Less likely to trip Significantly more expensive than a single-phase inverter
Higher system capacity and efficiency Can only be used with a three-phase power supply
Reduces issues with voltage rise

If you operate appliances that have a high-power consumption rate, you may find it worthwhile to install a three-phase solar inverter and system, as it can generally pull more power in and handle bigger loads.

But, if you are looking to avoid a higher price tag, you may find it just as well to install a single-phase solar system.

How much does it cost to install a 3-phase solar system?

The price of a three-phase solar system will vary depending on a number of factors such as system size, roofing space and the products chosen. According to SolarChoice though, you can expect a three-phase solar inverter to cost you around $500 more than a standard single-phase one.

3-Phase Solar Inverter Brands

There are a number of manufacturers that make three-phase solar inverters. Some of the top brands in the industry that produce these inverters include;

  • Fronius
  • SMA
  • SolarEdge
  • SunGrow
  • Huawei
  • Growatt

How to find the best solar installer

Whether you decide to install a single or three-phase solar system, you’ll still want to ensure that you are choosing a quality installer. There are a number of things to consider when picking an installer, from price to customer service and the quality of products they use. That’s why it’s a good idea to gather some quotes and do your research before committing to an installer.

If you’re not sure where to start, our annual customer satisfaction report compares a range of solar installation companies across areas such as overall satisfaction, set-up costs and customer service. To see which companies have come out on top this year, click the link below.

Compare Solar Installers

Image credit: vchal/Shutterstock.com, Kitch Bain/Shutterstock.com.

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