By AGILE Consulting Engineers, Solar PV and Battery Energy Storage Systems (BESS) specialists.
In Q2 2026, the average wholesale spot price across the National Electricity Market (NEM) was $74 per megawatt hour, down 47 per cent on the same quarter a year earlier, according to AEMO’s Quarterly Energy Dynamics report. That fall was driven largely by record renewable output and a rapidly expanding battery fleet, not by demand collapsing. For anyone designing or financing a virtual power plant (VPP) in Australia today, that single statistic says more about where trading value is heading than any amount of speculation about future market design.
Table of Contents
- Trading at the Edge of the Grid
- The Five-Minute Foundation Behind Modern DER Trading
- Wholesale Spot Price Exposure and Aggregated DER
- Two-Sided Tariffs and the Economics of Exporting
- Where VPPs Sit in FCAS and Ancillary Markets Today
- Emerging Market Mechanisms: Informed Forecasting, Not Fact
- What This Means for Project Economics
- What to Do Next
- FAQ
Trading at the Edge of the Grid
A VPP aggregates many small distributed energy resources (DER), household or commercial batteries, rooftop solar photovoltaic (PV) systems, and increasingly electric vehicle chargers, and coordinates them through an energy management system (EMS) or distributed energy resource management system (DERMS) so they can participate in wholesale and ancillary service markets as if they were a single asset. In the NEM, run by the Australian Energy Market Operator (AEMO), that participation increasingly touches the same wholesale spot price signals and Frequency Control Ancillary Services (FCAS) markets that large generators and grid-scale batteries trade in. What has changed over the past few years is not the basic concept, aggregation has been discussed since the mid-2010s, but the volume of DER now capable of responding, and the granularity of the price signals it can respond to.
The Five-Minute Foundation Behind Modern DER Trading
It is worth being precise about timing here, because this is often misdescribed as a future reform. The NEM has settled the wholesale spot price at five-minute resolution, aligned with dispatch intervals, since the five-minute settlement rule commenced on 1 October 2021, replacing the previous 30-minute settlement window. This shift, now several years established, rewarded fast-responding technologies, batteries and demand response among them, over slower plant that had previously been able to average its output across a 30-minute window. For VPP operators, five-minute settlement is the foundational market design that makes aggregated battery dispatch commercially meaningful: a fleet of batteries that can shift output within a five-minute interval can now capture price volatility that would have been smoothed away under the old settlement regime. Any discussion of “the future of energy trading” needs to start from this already-existing baseline, not treat it as a change still to come.
Wholesale Spot Price Exposure and Aggregated DER
AEMO’s Quarterly Energy Dynamics report for Q2 2026 recorded a NEM-wide average wholesale spot price of $74 per megawatt hour, with Victoria the lowest at $56 per megawatt hour and South Australia the highest at $86 per megawatt hour, both down sharply year on year. The report attributes much of the fall to record renewable generation, which reached a Q2 share of 42.1 per cent of NEM supply, up from 37.1 per cent in Q2 2025, alongside a household battery fleet that grew by roughly 3.3 gigawatt hours, or 41 per cent, during the quarter. This is the pattern a VPP operator needs to plan around: average prices are trending down as rooftop solar and batteries expand, but price volatility, the gap between the cheapest and most expensive five-minute intervals in a day, is what a well-managed aggregated fleet can still capture. A VPP that only chases the average price will find its revenue eroding as more DER enters the market; one that is genuinely responsive to five-minute price signals has a better chance of capturing the shrinking but still real volatility premium.
Two-Sided Tariffs and the Economics of Exporting
Network tariffs are moving in a direction that VPP economics cannot ignore. The Australian Energy Regulator’s export tariff guidelines allow distribution networks to introduce two-way tariffs, meaning a charge or rebate on exported energy rather than treating exports as free, in locations where DER is materially driving network costs. This is not a blanket, nationwide charge; it applies where a network proposes it and the regulator approves it. Examples already in place include Essential Energy’s export charge of roughly 0.8 cents per kilowatt hour for exports above a daily free threshold during the middle of the day, and SA Power Networks’ charge of around 1 cent per kilowatt hour above its own daily threshold, both applied only during peak solar export hours. For a VPP managing behind-the-meter batteries, this changes the calculation: a battery that simply exports whenever the sun shines may face a modest export charge, while one that is dispatched intelligently, holding charge back from the free-export window and discharging into higher-value evening periods, avoids that charge and captures better wholesale value at the same time. Two-sided tariffs, in other words, make smart dispatch more valuable, not less.
Where VPPs Sit in FCAS and Ancillary Markets Today
Beyond the wholesale spot market, FCAS remains a meaningful revenue stream for well-specified VPP fleets. AEMO’s current Market Ancillary Service Specification, in effect since October 2023, introduced very fast raise and lower FCAS categories alongside the existing fast, slow and delayed bands, widening the field of ancillary services that a sufficiently responsive aggregated battery fleet can register for. Participation requires the fleet to be verified against AEMO’s metering and performance requirements for the category it registers in, which is a genuine technical bar, not a formality. For engineering teams, this means FCAS revenue should be modelled as a real but conditional income stream, dependent on the platform’s demonstrated telemetry performance and AEMO’s verification process, rather than assumed as a guaranteed baseline return.
Emerging Market Mechanisms: Informed Forecasting, Not Fact
Looking further ahead, AEMO’s broader DER Program, including work under Project EDGE, has trialled dynamic operating envelopes (DOEs), which are time-varying limits on how much a connected DER can import or export at a given network location, set to reflect real-time network capacity rather than a fixed, conservative limit. Project EDGE’s published findings suggest that close-to-real-time forecast DOEs outperform day-ahead approaches because they better capture actual network voltage conditions. It is reasonable to expect, as an informed forecast rather than a settled fact, that DOEs will become a more standard feature of DER connection agreements over the coming years, and that this could eventually support more DER participating directly, or through aggregation, in local network markets as well as the wholesale market. Similarly, ongoing rule change processes around DER participation in the wholesale market may in time create clearer pathways for smaller aggregated fleets, but engineering and investment decisions today should be based on current registration categories, not on mechanisms that have not yet been finalised.
What This Means for Project Economics
For a project developer or asset owner, the practical implication is that revenue stacking, wholesale spot exposure, FCAS participation and network tariff optimisation together, is now genuinely achievable but needs to be modelled with realistic assumptions about falling average prices, tightening export conditions, and a verification bar for ancillary services that not every platform clears. Overstating any single revenue stream in a business case is one of the more common ways BESS projects underdeliver against their financial model once operating data comes in.
What to Do Next
Modelling a BESS project’s revenue stack against current NEM conditions, rather than optimistic assumptions from a few years ago, is the kind of technical review that is far cheaper to do before financial close than after. We have worked through exactly this kind of revenue and compliance modelling with project teams before they committed to hardware or an aggregation contract, and it typically changes at least one assumption in the business case.
FAQ
Is five-minute settlement a new change in the NEM?
No, five-minute settlement has been in effect since 1 October 2021, and it underpins how aggregated battery fleets currently capture wholesale price volatility, rather than being an upcoming reform.
Are wholesale electricity prices in the NEM currently rising or falling?
According to AEMO’s Quarterly Energy Dynamics report, NEM-wide average wholesale spot prices fell 47 per cent year on year to $74 per megawatt hour in Q2 2026, driven by record renewable generation and battery growth.
What is a two-way or two-sided network tariff?
It is a network tariff structure that applies a charge or rebate to exported electricity, not just consumption, and is being introduced by some distribution networks, with regulatory approval, in areas where solar exports are driving network costs.
Can a small aggregated battery fleet participate in FCAS markets?
Yes, provided the fleet can be verified against AEMO’s Market Ancillary Service Specification requirements for the specific FCAS category, which depends on telemetry performance and metering compliance rather than just battery capacity.
What is a dynamic operating envelope?
A dynamic operating envelope (DOE) is a time-varying limit on how much power a connected DER can import or export at its network connection point, designed to reflect real-time network capacity rather than a fixed, conservative limit.
Should a VPP business case assume guaranteed FCAS revenue?
No, FCAS revenue depends on successful registration and ongoing verified performance, so it should be modelled as a conditional revenue stream rather than a guaranteed baseline in a project’s financial case.
