Why Battery Developers Can No Longer Rely on Gentailer Contracts
Battery developers in Australia are facing a structural shift in how projects are financed and brought to market. What once worked in renewable energy no longer applies in the same way to battery storage. For developers navigating battery project finance, the decline of gentailer contracts is creating both a challenge and a turning point.
Australia’s energy system is evolving. The National Electricity Market is becoming more dynamic, and traditional offtake models are no longer keeping pace with how battery storage operates. This has created a clear problem for developers who previously relied on gentailers to secure revenue certainty.
What a gentailer contract is and why developers have depended on it
Gentailers are companies that both generate and retail electricity. In Australia, they have historically played a central role in the energy market by offering long-term contracts to developers. These contracts, often structured as Power Purchase Agreements, provided stable revenue, long-term certainty, and clear pathways to financing. For traditional generation assets, the model worked well.
Why developers relied on gentailers
Battery developers depended on gentailers for one key reason: revenue certainty. With a contract in place, cash flows were predictable, lenders were more willing to provide debt, and projects could move towards construction. Gentailer contracts were a cornerstone of battery project finance.
Why gentailers are withdrawing from battery offtake
In recent years, the role of gentailers has started to change. Companies such as AGL, Origin Energy, and EnergyAustralia are increasingly pursuing own-build battery strategies rather than signing bankable offtake agreements for third-party BESS assets. This is not a temporary shift. It reflects deeper changes in the market.
Key reasons behind the withdrawal
- AGL is targeting 3 GW by FY30 through its own development pipeline; Origin has committed $1.7 billion to 1.7 GW; EnergyAustralia is targeting 1.6 GW by 2030, with the Yallourn coal retirement (mid-2028) driving urgency. Each is reserving battery storage capacity to serve its own portfolio.
- Battery storage provides critical portfolio value that gentailers want to own and control: hedging thermal outages, capturing wholesale volatility, firming renewable intermittency, and managing FCAS obligations.
- Where gentailers do engage with third-party BESS, the arrangements are portfolio-serving rather than scalable. Origin Energy has tolled approximately 740 MW from two third-party counterparties as portfolio-serving arrangements, not as scalable offtake for independent developers. EnergyAustralia has one bespoke virtual deal.
Gentailers are no longer willing to take on the same level of risk they once did.
The impact on developers
For battery developers in Australia, this creates a substantial challenge: fewer available contracts, increased reliance on merchant revenue, and greater difficulty in securing financing. This is the core of the battery developer problem in today’s market.
The structural mismatch between batteries and traditional offtake
The decline of gentailer contracts is not just about market conditions. It is also about structural mismatch. Battery storage operates differently from traditional generation assets.
How batteries generate revenue
Battery projects earn income through energy arbitrage in the National Electricity Market, participation in the eight Frequency Control Ancillary Services markets (six contingency services responding in milliseconds to events, plus two regulation services making continuous small adjustments), and network support agreements that respond to real-time price signals. These revenue streams are dynamic and depend on market conditions.
Why traditional offtake does not fit
Traditional contracts are designed for assets with predictable output. Batteries do not produce energy in a fixed pattern. This creates difficulty in defining contracted volumes, misalignment between contract structure and asset operation, and reduced flexibility for optimisation. As a result, traditional battery storage revenue contract models in Australia are becoming less effective.
What developers need to do now that gentailer contracts are gone
With the decline of gentailer contracts, developers must adopt new approaches to project structuring.
Focus on revenue certainty
The key priority is the same: revenue certainty. Without it, projects struggle to achieve bankability for battery storage, lenders remain cautious, and timelines extend.
Shift towards new financial solutions
Developers are increasingly turning to Revenue Swap Agreements to address this challenge. These agreements are documented under an ISDA 2002 Master Agreement with the AFMA Electricity Addendum, providing a standardised framework for financial settlement. They provide stable revenue profiles, reduce exposure to market volatility, and align with how batteries operate. Unlike traditional contracts, they do not restrict market participation.
Supporting Financial Close
By stabilising revenue, these solutions help projects reach Financial Close for battery projects. Financial Close is the milestone at which all legal and commercial agreements with lenders and investors are fully executed, all conditions precedent have been satisfied, and the initial capital drawdowns commence, with the project officially moving into the construction phase.
The role of advanced modelling
Accurate modelling is essential in this new environment. Vol-OS, Basis Energy’s proprietary pricing, dispatch, and governance engine, allows developers to simulate market conditions, assess revenue variability, and build stronger financial cases. This level of analysis is becoming a standard requirement for securing investment.
A new era for battery project structuring
Battery developers in Australia are entering a new phase where traditional approaches are no longer sufficient. Gentailer contracts once provided a clear path to financing. That path is now narrowing.
The market is moving towards structures that reflect how battery storage actually operates. Revenue certainty, flexibility, and alignment with market dynamics are becoming the new standard. Developers who adapt to new revenue models will be able to move projects forward. Those who rely on outdated structures will face delays.
The opportunity remains strong. Success now depends on how effectively projects are originated and financed in an evolving energy market.
FAQs
Why can battery developers in Australia no longer rely on gentailer contracts?
Because the major gentailers (AGL, Origin Energy, and EnergyAustralia) are increasingly pursuing own-build battery strategies rather than signing bankable offtake agreements for third-party BESS assets.
What is a gentailer contract in battery storage?
It is typically a long-term agreement where a retailer purchases electricity or services from a battery project, providing revenue certainty.
What is the main challenge battery developers face today?
Securing predictable revenue in a volatile market without relying on traditional offtake agreements.
How are developers solving the battery developer problem?
Developers are using financial solutions such as Revenue Swap Agreements to stabilise income and improve project bankability.
