What is 3-phase power? And how do I know if my house needs it?

Asma Aziz, Edith Cowan University

If you’re building, renovating or planning to install a solar battery, your builder or installer might ask whether you’ve considered upgrading from single-phase to three-phase power. This upgrade often comes with a hefty price tag.

So what’s the difference between single-phase and three-phase power, and which one will you need?

Understanding your electricity needs

Each house service connection has a maximum amount of electricity that can be drawn from the grid at any one time before the main fuse blows. The limit varies, according to whether you have single- or three-phase power.

The amount is calculated by multiplying a house’s “amps” and “voltage”.

An “amp” is a unit of electric current. Most houses in Australia with single-phase connections have a standard capacity of 63 amps.

In New South Wales, the standard is 100 amps.

However, some older or rural homes in Australia may still have connections of 32 or 40 amps.

Then there’s voltage, which is the pressure that pushes the current through your wiring to power your house. Current and voltage values are determined by the local distribution network service provider, the company that owns and operates the poles and wires.

Since 2000, the standard voltage in most areas of Australia has been 230 volts. In Western Australia, it’s 240 volts.

Multiplying 240 volts by 63 amps gives you 15,120 watts of power (a watt is a unit of power).

So that means in a home with single-phase power, you can draw about 15,120 watts (or about 15 kilowatts) of power from the grid before the main fuse blows.

But this would probably require using all your appliances at the same time – an unlikely scenario.

Your energy bill can help you understand how much energy you’re using (and you can compare to how much other Australians use). When you see kWh (kilowatt hour) on your monthly energy bill, it’s a measurement of your electric appliances’ wattage and the amount of time you use them.

If you can reduce the amount of energy you need to draw from the grid, you might not need to upgrade to three-phase power at all. Solar panels and a battery can cut your electricity bills, keep the lights on during power outages, and reduce your carbon footprint. Plus, you can store energy for later use, boosting your home’s energy independence.

What’s the difference between single-phase and 3-phase power?

Think of single-phase power as a single-lane road.

It’s perfect for handling regular household appliances such as lights, fridges, washing machines, small air conditioners, small induction cooktops, and regular wall chargers for electric vehicles.

But if too many appliances are running at once, the single-phase circuit in your home can get congested. This can lead to issues such as tripping breakers or flickering lights.

Three-phase power is more like a three-lane highway, with each phase carrying peak power at a different point of time.

It’s designed to handle heavy loads such as a more powerful electric vehicle charger, large multi-zone ducted air conditioning systems, high-end and large induction cooktops and their combinations.

Do you need 3-phase power?

For most households, single-phase power is more than enough to keep everything running smoothly.

Unless you’re running a big property with a large swimming pool, fast-charging your electric car, operating an elevator, cranking up ducted air conditioning, baking in multiple ovens, and powering a high-end kitchen full of gadgets – all at the same time – you probably don’t need to make the switch.

That’s good news, because upgrading to three-phase power can be quite pricey (potentially thousands of dollars).

Equipping every house with three-phase power would be like giving everyone a sports car when a regular car does the job just fine.

Installing three-phase power in every home would make the network infrastructure more expensive to build and maintain. Most homes don’t need that much power, so the extra capacity would go to waste – but everyone would still be paying for maintenance of that larger, underutilised system via higher energy bills.

However, things may be changing

As more homes go all-electric and solar battery systems and electric vehicles become the norm, however, more people will switch to three-phase power.

Three-phase power unlocks incredible charging speeds for electric vehicles (but before you get too excited, make sure your car is equipped to handle that extra juice).

You might think it’s smart to get a much bigger solar panel system than you need, so you can earn extra money from feed-in tariffs by exporting excess energy to the grid. However, single-phase rooftop solar can only feed up to five kilowatts at any point in time in a day to the grid. If your system goes over that, you’ll need special approval to connect it.

Switching to three-phase power can be a great move if you’re looking to install a larger solar system. It lets you harness more energy for your home and potentially send more power back to the grid. It’s worth noting that in Australia, however, the amount of solar power you can export varies by state.

For bigger setups, such as solar systems with batteries that can handle up to 30 kilowatts, three-phase power might be necessary. An electrician will ensure everything stays balanced in your connection.

For most of us, the best way to work out whether you need single- or three-phase power is to work out your total electricity use and seek advice from a registered electrical contractor you trust.

Some will calculate how much power you’d need if you were running all the appliances and powered devices in your home at full blast, all at once. But it’s worth questioning whether this scenario would ever actually happen in real life.

No one wants to overspend on something they don’t actually need.

Asma Aziz, Senior Lecturer in Power Engineering, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→October 01, 2024

Renewables are cheap. So why isn’t your power bill falling?

Tony Wood, Grattan Institute

Power prices are set to go up again even though renewables now account for 40% of the electricity in Australia’s main grid – close to quadruple the clean power we had just 15 years ago. How can that be, given renewables are the cheapest form of newly built power generation?

This is a fair question. As Australia heads for a federal election campaign likely to focus on the rising cost of living, many of us are wondering when, exactly, cheap renewables will bring cheap power.

The simple answer is – not yet. While solar and wind farms produce power at remarkably low cost, they need to be built where it’s sunny or windy. Our existing transmission lines link gas and coal power stations to cities. Connecting renewables to the grid requires expensive new transmission lines, as well as storage for when the wind isn’t blowing or the sun isn’t shining.

Notably, Victoria’s mooted price increase of 0.7% was much lower than other states, which would be as high as 8.9% in parts of New South Wales. This is due to Victoria’s influx of renewables – and good connections to other states. Because Victoria can draw cheap wind from South Australia, hydroelectricity from Tasmania or coal power from New South Wales through a good transmission line network, it has kept wholesale prices the lowest in the national energy market since 2020.

While it was foolish for the Albanese government to promise more renewables would lower power bills by a specific amount, the path we are on is still the right one.

That’s because most of our coal plants are near the end of their life. Breakdowns are more common and reliability is dropping. Building new coal plants would be expensive too. New gas would be pricier still. And the Coalition’s nuclear plan would be both very expensive and arrive sometime in the 2040s, far too late to help.

Renewables are cheap, building a better grid is not

The reason solar is so cheap and wind not too far behind is because there is no fuel. There’s no need to keep pipelines of gas flowing or trainloads of coal arriving to be burned.

But sun and wind are intermittent. During clear sunny days, the National Energy Market can get so much solar that power prices actually turn negative. Similarly, long windy periods can drive down power prices. But when the sun goes down and the wind stops, we still need power.

This is why grid planners want to be able to draw on renewable sources from a wide range of locations. If it’s not windy on land, there will always be wind at sea. To connect these new sources to the grid, though, requires another 10,000 kilometres of high voltage transmission lines to add to our existing 40,000 km. These are expensive and cost blowouts have become common. In some areas, strong objections from rural residents are adding years of delay and extra cost.

So while the cost of generating power from renewables is very low, we have underestimated the cost of getting this power to markets as well as ensuring the power can be “firmed”. Firming is when electricity from variable renewable sources is turned into a commodity able to be turned on or off as needed and is generally done by storing power in pumped hydro schemes or in grid-scale batteries.

In fact, the cost of transmission and firming is broadly offsetting the lower input costs from renewables.

Does this mean the renewable path was wrong?

At both federal and state levels, Labor ministers have made an error in claiming renewables would directly translate to lower power prices.

But consider the counterpoint. Let’s say the Coalition gets in, rips up plans for offshore wind zones and puts the renewable transition on ice. What happens then?

Our coal plants would continue to age, leading to more frequent breakdowns and unreliable power, especially during summer peak demand. Gas is so expensive as to be a last resort. Nuclear would be far in the future. What would be left? Quite likely, expensive retrofits of existing coal plants.

If we stick to the path of the green energy transition, we should expect power price rises to moderate. With more interconnections and transmission lines, we can accommodate more clean power from more sources, reducing the chance of price spikes and adding vital resilience to the grid. If an extreme weather event takes out one transmission line, power can still flow from others.

Storing electricity will be a game-changer

Until now, storing electricity at scale for later use hasn’t been possible. That means grid operators have to constantly match supply and demand. To cope with peak demand, such as a heatwave over summer, we have very expensive gas peaking plants which sit idle nearly all the time.

Solar has only made the challenge harder, as we get floods of solar at peak times and nothing in the evening when we use most of our power. Our coal plants do not deal well with being turned off and on to accommodate solar floods.

The good news is, storage is solving most of these problems. Being able to keep hours or even days of power stored in batteries or in elevated reservoirs at hydroelectric plants gives authorities much more flexibility in how they match supply and demand.

We will never see power “too cheap to meter”, as advocates once said of the nuclear industry. But over time, we should see price rises ease.

For our leaders and energy authorities, this is a tricky time. They must ensure our large-scale transmission line interconnectors actually get built, juggle the flood of renewables, ensure storage comes online, manage the exit of coal plants and try not to affect power prices. Pretty straightforward.

Tony Wood, Program Director, Energy, Grattan Institute

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→March 22, 2025