The WA
Energy Market

Fun Facts

  • WEM stands for Wholesale Electricity Market. It is the collection of electricity generators, customers, and electricity retailers

  • The WEM provides electricity to more than 1.1 million households and businesses

  • The SWIS is the South West Interconnected System, the largest electricity grid in Western Australia which is maintained and operated by Western Power

  • The SWIS incorporates over 7,800 km of transmission lines and over 64,000 km of distribution lines

  • One in three houses on the SWIS has rooftop solar panels

  • The WA energy market has a system peak of around 4,000 MW, and an average demand of about 2,000 MW

  • The power system is under the most strain during high demand days between 4PM to 7PM, usually after a few hot days

  • On an average summer day, the lowest demand period during daylight hours is between 11AM and 2PM. Using electricity at this time puts the least amount of strain on our energy systems and helps to keep your rates low

  • Do you have solar panels? Did you know that solar panels produce their most output at around 1PM? At 6PM, this output reduces to around 20%, depending on the direction they face

  • There is over 1,000 MW of rooftop solar, making this the largest combined generator on the grid

  • AEMO is responsible for operating the WEM in accordance with the Wholesale Electricity Market rules (WEM rules) and the related WEM market procedures. Other key entities which play important roles in the electricity policy include:

    • The WA Minister for Energy can approve proposed changes to protected provisions in the Rules and has the ability to amend rules

    • Energy Policy WA

    • Department of Treasury

    • The Economic Regulation Authority which performs regulatory and market surveillance roles and monitors and enforces compliance with the WEM Rules

    • The independent Rule Change Panel which undertakes the administration and decision-making functions for changes to the Rules

    • The Electricity Review Board which acts as an adjudicator for appeals

How Electricity
Gets To Your Business

  1. Electricity is produced in large generators, like a coal or gas power station, or a wind or solar farm

  2. Transformers convert the energy to high voltage for more efficient transportation

  3. The transmission lines carry electricity long distances

  4. Substations convert high voltage electricity to low voltage for use

  5. Distribution power lines carry the low voltage electricity to your business or home

  6. The electricity is consumed

  7. Rooftop solar and batteries generate or store electricity to provide support for the grid and provide cheap electricity for users

How Electricity Retail Works

  1. You use the electricity at work or home

  2. Your electricity provider decides where to buy your electricity from, being either a contract with a power station, other wholesale options, or from their own generation

  3. AEMO ensures that your lights won’t go off, regardless of how your electricity retailer sources your electricity

  4. Western Power reads your meter and gives that information to your electricity retailer and AEMO

  5. Your electricity retailer calculates your charges and sends you a bill for your usage, usually once a month

  6. Western Power charges your electricity retailer for maintenance and management of the electricity network, which they have built into your rates

  7. AEMO sends a bill to your electricity provider for your electricity charges, your capacity charges and some other fees which help keep the industry running