REZs are how Australia plans where new wind and solar connect. Here is what they are, who designates them and why they matter for connection, loss factors and curtailment.
A Renewable Energy Zone is a designated area that pairs strong wind or solar resource with coordinated transmission. Instead of each project building its own long connection and discovering the network limits the hard way, a zone plans the shared transmission up front so generation can connect in clusters. REZs are a central building block of the grid’s transition from a small number of large thermal sites to many dispersed generators.
The best wind and solar resource is often far from the existing transmission that was built around coal and gas sites. Connecting one project at a time to a weak part of the network is slow and expensive, and it leaves later projects exposed to congestion. Grouping generation into planned zones spreads the cost of new transmission, gives developers a clearer connection pathway and lets the operator plan the network around where generation is actually going.
AEMO identifies candidate zones in its Integrated System Plan, the biennial roadmap for the NEM. State governments then formalise and develop them through their own schemes, such as the NSW Electricity Infrastructure Roadmap, with comparable programs in Victoria and Queensland. The result is a published set of zones, each with an indicative transmission build and a resource profile.
A zone is not a guarantee of smooth revenue. As more capacity connects to the same part of the network, the shared transmission can fill up, and output gets constrained off when it cannot all be exported. That congestion shows up two ways for a generator: in marginal loss factors, which scale the price a unit is paid for its location, and in curtailment, where output is cut during binding constraints. Both feed straight into a project’s delivered revenue and any PPA built on top of it.
MLF = marginal loss factor. Curtailment = output reduced when the network cannot take it all.
What is a renewable energy zone?
A Renewable Energy Zone (REZ) is a designated area that combines strong wind or solar resource with coordinated transmission investment, so that new generation can connect in clusters rather than one project at a time.
Who decides where REZs go?
AEMO identifies candidate zones in the Integrated System Plan, and state governments formalise and develop them through schemes such as the NSW Electricity Infrastructure Roadmap and equivalent programs in Victoria and Queensland.
How do REZs affect generators?
Connecting inside a well-planned zone can lower connection cost and transmission risk, but clustering generation also concentrates congestion. That shows up in marginal loss factors and curtailment, which directly affect a project’s delivered revenue.
gridIQ tracks REZ data from the ISP, marginal loss factors and live curtailment, so developers and PPA buyers can see how a connection point actually performs. Watt answers the questions in plain language.
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