Electricity is supplied and controlled by different types of supply, providing electricity throughout the nation, from urban hubs linked to public utilities to off-grid rural or remote areas. Knowledge of these types is essential for Australians residing in large cities as well as rural or remote areas. Five principal types of electrical supply systems are explained in this article: normal, grid, alternative, supplementary, and independent.

1. Normal Supply

Normal supply is the standard electricity offered by the public utility grid. It is the most typical source of power for industry, homes, and commercial customers in Australia. It offers stable, regulated power on demand and is operated by national or local electricity authorities like the Australian Energy Market Operator (AEMO).

Key Features of Normal Supply:

• ▪ Public Grid: An enormous system of power stations, high-voltage transmission lines, substations, and distribution lines that supply electricity throughout Australia. The National Electricity Market (NEM) interconnects the eastern and southern states, Western Australia in isolation.
• ▪ Generation: Australia’s generation is powered by a combination of sources. Although coal-fired power stations remain dominant in New South Wales and Queensland, renewable energy sources are climbing sharply, with solar and wind taking over. As per recent reports, South Australia is leading the charge in bringing renewable energy into the grid.
• ▪ Transmission and Distribution: Electricity is transmitted over long distances at high voltage via wires, reduced to lower voltage in substations, and delivered to homes and businesses.
• ▪ Service Drop: The last connection into a consumer switchboard, usually from power poles or underground cables.
• ▪ Alternating Current (AC): As with all major public networks in the balance of the world, Australia’s network provides electricity in AC, single-phase current for most houses and three-phase current for larger buildings and industrial estates.

For cities such as Sydney or Melbourne, normal supply is the primary source of energy. Nevertheless, in the event of an outage or failure, backup can be provided by other systems.

2. Supplementary Supply

Backup supply is duplicate systems running in parallel with the normal grid supply, providing additional power when there is a need. They are not meant to substitute the grid but provide backup power, which makes it more stable, minimizes grid load, and helps in its maintenance.

Typical Supplement Systems in Australia:

• ▪ Grid-Connected Solar Photovoltaic Systems: Uptake of the Solar PV system has risen across Australia, more so in Queensland, New South Wales, and Victoria states where sunlight is in abundance and hence solar energy is a desirable option. Such systems are cost-saving on electricity bills and sell back excess energy to the grid under feed-in tariff terms, mainly during daytime.
• ▪ Backup Generators: Diesel or gasoline generators are generally locally installed or for short-duration backup in office buildings. They are especially prevalent in the mining industry, where power is constantly needed.
• ▪ Microgrids: A number of remote villages in Far North Queensland or the Pilbara, Western Australia, utilize microgrids operating in isolated mode or grid-synchronized mode. Such systems may utilize solar, wind, or diesel generation and disconnect during a grid failure or peak demand interval.

Benefits of Supplemental Supply in Australia

• ▪ Reliability: Solar and other alternative systems ensure the limiting of power failures at peak summer demand periods in urban centers such as Adelaide, where heatwaves tend to strain the electricity supply.
• ▪ Cost Efficiency: Solar power residential and business consumers in Australia minimize the price of electricity, particularly in areas with costly energy charges.
• ▪ Environmental Impact: As Australia keeps moving towards renewable energy, stand-by systems such as solar and wind contribute to reducing the reliance on fossil fuels and carbon emissions.

3. Alternative Supply

Alternative supply is stand-by systems that are in operation to supply electricity in case of power failure. As opposed to supplementary systems, which operate parallel to the grid, alternative systems are in operation during power failure to ensure continuity.

Types of Alternative Supply in Australia:

• ▪ Grid-Connected with Automatic Transfer Switch (ATS): These are normally fitted in commercial buildings and priority buildings such as hospitals. The ATS can identify grid failure and transfer to standby such as generators or batteries. For instance, the Royal Melbourne Hospital utilizes such systems to guarantee a continuous power supply during emergencies.
• ▪ Stand-alone Systems with Manual Transfer: In geographically remote areas like Tasmania or the Outback, local batteries or generators are utilized as auxiliary sources. These should have manual intervention to transfer from grid to auxiliary supply during interruption.

Examples of Alternative Supply:

• ▪ Generators: Utilized in locations such as Katherine (Northern Territory) or Western Australian mining camps. Such facilities tend to use backup generators to provide round-the-clock power during grid outages.
• ▪ Battery Storage Systems: In states like South Australia, residential users with solar PV systems usually couple these systems with Tesla Powerwall batteries to avoid losing power supply during power outages, especially during adverse weather conditions.
• ▪ Renewables with Backup: In regions prone to bushfire, such as parts of Victoria, renewable systems (wind and solar) are increasingly being linked with backup generators to ensure constant power in the event of a crisis and lower the carbon footprint of backup systems.

4. Independent Supply

Independent supply, or stand-alone or off-grid systems, is totally self-sufficient, drawing on its own generation and storage.

Key Features of Independent Supply in Australia:

• ▪ Self-Sufficiency: Such systems produce and use electricity independent of the national grid. They are found in remote areas of Australia, such as rural Queensland or Western Australia properties, where grid supply is absent or not economically feasible.
• ▪ Renewable Energy: Solar and wind energy, augmented by batteries, are the chief sources of energy for off-grid homes or businesses.
• ▪ Energy Storage: SonnenBatterie or BYD Battery-Box batteries store surplus energy for off-peak or low-generation periods.
• ▪ Backup Sources: Periodically, a diesel generator could be installed to provide power during prolonged periods of adverse weather or heavy use.

Typical Uses in Australia:

• ▪ Remote Sites: Outback New South Wales or Central Australia service stations, cabins, and farms are most likely to be off-grid due to the distance from the grid.
• ▪ Eco-Homes: Most Australians who adopt energy independence or sustainable lifestyle are fitting off-grid systems. In Blue Mountains (NSW), eco-homes increasingly use solar power, batteries, and standby generators to disconnect from the public grid.

Considerations:

Independent systems are expensive both in installation and upkeep. However, for those in remote locations or who want energy autonomy, such systems grant autonomy. Environmental sustainability is also involved as it seeks to reduce the carbon footprint of Australia.

5. Grid-Connected vs. Off-Grid Systems

Their strengths and weaknesses are highlighted by comparing grid-connected and off-grid systems.

Grid-Connected (On-Grid) Systems:

They are connected to the grid, and extra energy can be fed back to the grid, which is commonly exempted by net metering laws in such places as Queensland or New South Wales.

Off-Grid Systems:

They are independent and distinct from the grid, and battery storage facilities large enough are required in order to provide electricity at low generation periods.

Hybrid Systems in Australia

Hybrid systems, which offer grid connection as well as autonomy, are becoming popular in Victoria and South Australia. They enable consumers to utilize solar power, store electricity, and stay connected to the grid as a back-up, providing maximum energy efficiency.