South West Interconnected System
Western Australia is special in many ways, from our abundant biodiversity and ancient landscapes to our unparalleled lifestyles. It only makes sense that our main electricity system - the South West Interconnected System, or SWIS - is also unique.
Stretching from Kalbarri in the north to Albany in the south and Kalgoorlie in the east, the SWIS is one of the most isolated large electricity grids in the world. It’s an energy island separated from the national Australian electricity grid by over 1,000 kilometres of desert.
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Customers, including households, hospitals, businesses, schools and major industry
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Of WA’s population lives within the SWIS footprint
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Renewable generation capacity on the SWIS
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Renewable energy in 2025
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Information is indicative only
SWIS Transmission Upgrades
- Planning and scoping
- Under construction
Energy type
- Wind
- Battery
- Solar
- Hydro
Retiring coal
We are retiring the remaining State-owned coal power plants on the SWIS as part of our push to cut our State’s emissions. This is an important part of our work to decarbonise our State - but it is also driven by the economic realities of operating these ageing plants.
Rooftop solar has changed our supply and demand patterns and lowered daytime wholesale prices, which is changing coal’s role on the system. At the same time, coal prices are rising, making coal-fired power plants more expensive to run.
This means coal is no longer fit for purpose for WA. So, we are replacing coal with new wind and solar farms supported by energy storage and gas, keeping energy affordable and reliable while we decarbonise.
Our main grid is already changing
As recently as a decade ago, the idea of WA becoming a renewable energy powerhouse seemed far-fetched. But since then, things have changed dramatically: a more than threefold increase in renewable penetration on the State’s main grid. World-leading uptake of rooftop solar underpinning renewable penetration that can rise to over 85%. Significant investment in energy storage, flattening price fluctuations and unlocking the full value of clean energy generation while keeping prices stable. While there remains more to do, we should be proud of our State's progress over the last decade.
Future-ready transmission
New renewable or battery projects can’t connect to the SWIS without transmission. And we can’t power new industries without upgraded transmission links either. This means that expanding and upgrading the transmission network is essential for a cleaner energy mix on the SWIS and a stronger WA economy. That's why we're investing in the Western Power, funding the projects outlined in the SWIS Transmission Plan to connect more renewables and take the next step in our energy transition.
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A Smarter Energy System
Distributed Energy Resources (DER) are smaller-scale energy devices that use, generate or store electricity – for example, electric vehicles, rooftop solar and home batteries.
WA is a world leader in the take-up and integration of DER. The SWIS has some of the highest levels of DER in Australia and is a global leader in rooftop solar penetration on the grid. Today, over 40% of homes on the system have rooftop solar installed - and we expect this to rise to 50% by 2030.
This rooftop solar underpins over 2.5 gigawatts of distributed solar generation across the broader system. That's more than three times the generation capacity of the remaining State-owned coal power plants in Collie.
To fully harness the massive potential of DER in WA, the State Government has taken a staged, place-based approach to DER integration, guided by the DER Roadmap.
