V1.1 · What a virtual power plant actually delivers
A virtual power plant does not create electricity in software. It turns the controllable behaviour of distributed equipment into a coordinated service that somebody can request, measure and pay for. To understand it, we will distinguish the physical equipment, the control system, the commercial promise and the evidence of delivery. The lesson starts with an ordinary battery and EV charger, not with market terminology.
Read the concepts and system relationships in sequence before attempting the workshop. Key terms are explained in the context of their function. If a task is unclear, return to its section and explain the reasoning before calculating.
What should you be able to judge after this lesson?
- Explain what is virtual and what remains physical in a VPP.
- Describe how generation, storage and controllable demand can contribute different responses.
- Distinguish VPP, microgrid, DERMS, site EMS and demand response by their purpose.
- Follow an event from available capability through commitment, dispatch, measurement and payment.
Information and control: this is where the service is coordinated
Service buyer or programme
Defines the change, timing, duration and verification requirements.
VPP coordinator
Commits against authorised capability, then allocates and tracks delivery.
Site control and equipment
Checks local/network constraints, executes valid requests and reports measurements and exceptions.
Physical electricity: every site retains its own boundary
Local resources and loads
Batteries, generation and controllable demand physically change the site state.
Local connection point (PCC)
Each site's metering boundary shows its net import or export change.
Actual electricity network
Flows obey physical network constraints; cloud coordination does not bypass a line.
1. Why coordinate small resources at all?
A grid must continually match electricity supply and demand while keeping equipment and networks within operating limits. A large generator can offer a substantial controllable change at one connection point. A household battery, commercial charger or factory load is individually smaller, but many such devices may collectively provide a useful change. Aggregation makes the combined response visible and manageable as a service.
For a simple example, one hundred batteries might each have permission and ability to increase discharge by 2 kW during a specified event. If all are genuinely available together, the arithmetic total is 200 kW. The aggregator still needs a way to know their current state, issue or configure valid responses, verify delivery and handle those that cannot respond. A spreadsheet listing one hundred nameplates is not that operating system.
The reason to aggregate is not only size. A coordinating party can manage a common interface, forecasting, dispatch and commercial administration. Those activities have costs, and correlated failures or network constraints may reduce the value. Aggregation therefore creates a potential service, not an automatic saving or guaranteed income.
2. “Virtual” refers to coordination, not to the electricity
A Virtual Power Plant (VPP) is a coordinated portfolio of Distributed Energy Resources (DERs). The resources may sit at different homes, businesses or campuses rather than inside one fenced generating station. Communications and control allow their authorised behaviour to be combined for a defined energy or grid service. EMA’s overview gives examples involving batteries, solar and adjustable EV charging. [1]
The electricity still follows the physical network and its constraints. A cloud platform cannot send a particular electron directly from one member to another or bypass a congested transformer. If a service is intended to relieve a local network problem, the location of the resources matters. Resources on the wrong part of the network may not relieve that problem even if their combined MW looks sufficient.
The portfolio can be presented through a common operational or commercial interface, but the exact registration and settlement form depends on the jurisdiction and service. A VPP does not necessarily own its member equipment, and membership does not necessarily transfer every control right. Those rights must come from the relevant agreements.
3. A resource contributes a change from its operating point
A battery can increase discharge, reduce charging, increase charging or reduce discharge, subject to its power and energy limits. A charger may reduce its demand without exporting anything. A flexible factory process may move consumption to a later time. A controllable generator may increase output if it has fuel, headroom and permission. These are different physical actions that can sometimes support the same requested net change.
Consider a site importing 0.5 MW. If controlled charging falls by 0.2 MW and everything else stays constant, import falls to 0.3 MW. The grid sees a 0.2 MW reduction in demand even though the site never exports. At the Point of Common Coupling (PCC), the site meets the external network. For this course, an upward response means an increase in net injection, or equivalently a reduction in net withdrawal, at the stated boundary. Always check the sign convention of the actual service.
Solar output depends on sunlight and operating conditions. Curtailing an operating inverter may provide a downward change, while upward headroom generally requires available irradiance, prior curtailment and suitable controls. Installed PV capacity is therefore not a freely dispatchable upward reserve. The same principle applies to every resource: ask what it can change now, not merely how large it is.
4. Understand the service before the market name
An energy-shifting service changes when electricity is produced or consumed, often in response to prices or a contracted schedule. A peak-reduction service lowers demand during a defined period. A network-support service addresses a location-specific constraint under an agreed arrangement. Each requires its own boundary, timing and verification; the label VPP does not make the services interchangeable.
Frequency services help correct the balance between generation and demand. Regulation addresses ongoing smaller deviations; contingency response supports recovery following a significant disturbance. AEMO’s FCAS guide distinguishes these purposes. [2] Some fast responses can be configured locally and triggered by measured frequency rather than waiting for a cloud message for every event. The approved service design determines the arrangement.
A service may pay for making capacity available, for delivered energy, for measured performance or through a negotiated contract. Not every scheme uses all these payment components. Voltage/reactive support and active-power services also differ; increasing MW is not a universal remedy for voltage problems. Ask what is being bought and what evidence determines payment.
5. VPP, microgrid, DERMS and EMS answer different questions
A microgrid organises loads and local resources within a defined electrical boundary as a controllable system, including the ability to operate independently where designed for islanding. [3] A VPP coordinates a portfolio for a defined service and may span many independent electrical boundaries. Joining a VPP does not give a house or campus the switching, protection, grid-forming capability or energy needed to survive a grid outage.
A site Energy Management System, or EMS, schedules and controls equipment within the site’s operating priorities. DERMS means Distributed Energy Resource Management System; in a utility context it can help monitor and coordinate DERs with network conditions. A VPP platform may organise a commercial portfolio and exchange information with either system. Products can overlap, but a product name does not tell you which organisation holds network authority or commercial liability.
Demand response means changing demand in response to a signal or arrangement; it can be delivered through a VPP, but need not be. An electricity retailer supplies or arranges electricity under a retail relationship; it may also aggregate resources, but those responsibilities should be distinguished. One company can hold several roles without making those roles identical.
6. Follow a complete event from capability to payment
Before an event, the coordinator collects asset state, predicts availability and reserves the response it can credibly offer. It must respect owner permissions and network limits. For a scheduled event, a commitment is followed by a valid instruction, local checking and execution. For a locally triggered frequency service, an approved enabled response can activate through the local control logic.
During delivery, measured power must be related to the requested service and measurement boundary. Afterwards, the parties reconcile performance, exceptions and payment under the applicable rules. A receipt showing that a device accepted a message is not proof of the delivered electrical change. Likewise a successful electrical response is not by itself proof of payment entitlement.
The service is only as strong as its weakest missing link. A portfolio with excellent optimisation but no owner permission cannot be safely offered. A portfolio with permission but no reliable measurements cannot establish what happened. An operational demonstration without a payment agreement does not establish a business case.
7. Availability has a time window, a duration and a location
Nameplate capacity is an equipment property. Available response is an operating claim at a stated time, relative to a baseline and subject to constraints. A 1 MW battery already discharging at 0.8 MW has only 0.2 MW of additional discharge headroom before other limits. A 0.4 MW response lasting ten minutes does not fulfil a 0.4 MW commitment lasting an hour.
Battery State of Charge (SOC) is an estimate of stored charge relative to the adopted reference capacity. Usable event energy depends on the protected SOC window, actual retained capacity, conversion losses and other duties. A charger’s flexibility depends on the vehicle being connected and enough time remaining to reach its departure requirement. A process load depends on operating consent and what happens when production resumes.
Adding individual maxima can overstate portfolio capability if they occur at different times or compete for the same connection. Geographic diversity can help with some risks, but common communications, weather, customer behaviour or a shared feeder can create correlated loss. A credible commitment uses simultaneous, service-specific availability, with an explicit allowance for uncertainty.
8. Baseline and rebound explain why “using less” needs evidence
For many demand-reduction arrangements, the question is not only what the meter recorded, but how that value compares with an agreed reference for what would otherwise have happened. That reference is the baseline. Other services may use directly measured generation or another verification method instead. Never assume every VPP product uses the same baseline rule.
If a factory stops production for an unrelated reason, a lower meter reading does not automatically demonstrate an instructed response. If a charger delays 50 kWh, that energy may need to be delivered later, subject to losses and the vehicle’s requirement. The later recovery is often called rebound. Peak relief can be useful even when total daily energy is unchanged, but the recovery must not create a new prohibited peak.
Agree the verification and recovery method before committing. Record the reference, actual power, event timing, operating changes and later recovery. These records protect both the asset owner and the service buyer from treating normal business changes as paid flexibility.
9. The owner participates only if the permitted value exceeds the sacrifice
An owner may join to reduce bills, receive a service payment or access a subsidised offer. In return, it may accept remote control, cycling, altered charging times, data sharing or constraints on other asset uses. An apparently high gross receipt can be unattractive after fees, energy costs, wear, lost site value and the owner’s risk tolerance are included.
Revenue stacking means combining compatible value streams, not selling the same physical headroom twice. A battery that reserves energy for an outage cannot simultaneously promise all that energy to an external service unless the priorities, overlap and replenishment are explicitly reconciled. Some services may be compatible; others may conflict in power, energy, timing or contract rights.
A site with strict backup duties, no controllable surplus, uncertain permissions or disproportionate integration cost may rationally decline. A pilot can still be valuable for learning, provided its objectives and costs are explicit. Neither installing a battery nor buying VPP software creates an obligation or a guarantee to earn market income.
Workshop: form a decision from the given inputs
Attempt these tasks before opening the reference answers.
- Explain what the VPP coordinates and whether these three sites become a microgrid.
- Calculate the initial arithmetic response and the response that lasts the full 15 minutes. Can the proposed 0.8 MW be committed on this evidence?
- Explain why installed PV cannot simply be added, and why reducing EV charging still helps without exporting.
- Calculate battery event energy and deferred charging energy, then identify what must be agreed before payment can be claimed.
Answer 1 · The common service does not erase electrical boundaries
The VPP coordinates authorised changes in battery discharge, EV demand and factory demand. The three sites remain electrically distinct and connected through the wider network. They do not become one islandable microgrid merely because one platform coordinates them. Each would need its own relevant electrical design and permissions for outage operation.
The output from this step should be: A diagram showing each local connection and a separate information/control relationship.
Answer 2 · The shortest resource limits the sustained offer
Initially, 0.4 + 0.2 + 0.3 = 0.9 MW is arithmetically available. After ten minutes the factory cannot maintain its response, leaving 0.4 + 0.2 = 0.6 MW. On the stated evidence, 0.8 MW for the whole 15 minutes is unsupported; the final five minutes are short by 0.2 MW.
A simplified 0.6 MW continuous offer fits the stated resource durations, but still needs network, qualification, permissions and uncertainty checks. Alternatively obtain a separately verified replacement for the last five minutes. Do not silently extend the factory’s consent or borrow protected battery reserve.
The output from this step should be: A time-based response schedule that shows the factory dropping out at minute 10.
Answer 3 · Net demand change matters; a nameplate is not a response
The PV nameplate does not establish the sunlight, current curtailment or controllable upward headroom during the event, so 0.5 MW cannot simply be added. EV demand reduction of 0.2 MW reduces withdrawal by that amount if the baseline and other conditions support the measurement. Export is not required for that physical effect, though the actual service must permit and verify it.
The output from this step should be: An operating-point note defining direction, baseline and the PV evidence still missing.
Answer 4 · Energy accounting and payment evidence are separate
The battery delivers 0.4 × 0.25 = 0.1 MWh of incremental AC event energy. Reducing EV charging by 0.2 MW for 15 minutes defers 0.2 × 0.25 = 0.05 MWh, or 50 kWh, measured at the assumed boundary. The EV energy must be rescheduled consistently with departure requirements and network limits; actual battery replenishment additionally depends on efficiency and other operation.
Before claiming payment, identify the authorised participant, applicable service and qualification, agreed verification reference, valid meter records and contractual deductions. The arithmetic demonstrates a teaching duty, not eligibility or revenue. Record incomplete items rather than converting nameplate capacity into an annual income forecast.
The output from this step should be: An event record and a recovery plan with qualification and payment items marked unresolved.
The key decision from this lesson
The VPP’s product is a verified, authorised change at a defined boundary and time. The portfolio, control platform and commercial agreement must all describe that same change.
Sources and scope
Reviewed 25 October 2026. Primary sources provide background; numbered references in the text identify the relevant documents below. Cases, calculations and action suggestions are original teaching derivations. They do not replace site specifications, network permissions or contract review.
[1] EMA · Virtual Power Plants · concept overview ↗
[2] AEMO · Guide to Frequency Control Ancillary Services · September 2025 ↗
[3] U.S. DOE · Microgrid Systems · definition and boundaries ↗