Flexibility Communication Protocols

A layered stack of communication protocols connects end-user devices (heat pumps, EV chargers, batteries) up through aggregators, DSOs, and TSOs. No single protocol covers the whole chain — different layers use different standards, often with competing or overlapping proposals. This page maps the full landscape as documented by RISE in Energimyndigheten ER 2025:35. (Source - Energimyndigheten ER 2025-35 Förbättra Flexibiliteten (2025))

Why a protocol stack

The flexibility signal chain involves at least four distinct communication tasks:

1. Market and aggregation: the market operator or DSO dispatches flexibility events to aggregators or directly to service providers
2. DER control: aggregators or energy management systems communicate with physical devices (EV chargers, batteries, inverters)
3. Local automation: devices within a building or premises coordinate with each other (home energy management systems, building automation)
4. Grid/critical infrastructure: DSO and TSO control centres communicate with substations, field equipment, and SCADA

Each layer has its own set of protocols, standardization bodies, and maturity levels. A flexibility provider operating end-to-end must implement protocols at each layer, creating integration complexity.

Layer 1 — Market and aggregation protocols

These protocols carry flexibility dispatch signals from system operators or aggregators down to service providers or customer systems.

OpenADR

Standard: IEC 62746-10-1 (International Electrotechnical Commission) Swedish status: Industry standard since 2023 — adopted by Energiföretagen Sverige following a market-wide evaluation. Used by E.ON Energidistribution, Ellevio, and growing number of DSOs for Villkorade Avtal. Architecture: server–client (VTN/VEN); REST/JSON in version 3.0.1 (recommended for new implementations); programmatic event dispatch and report-back. Detail: see OpenADR for the full treatment, including Swedish production implementations.

S2

Standard: EN 50491-12-2 (European) Origin: FlexiblePower Alliance / TNO (Netherlands) Purpose: Semantic interoperability — defines common data semantics for flexible energy devices regardless of underlying transport protocol. Technology-agnostic. Swedish status: Limited use; evaluated in research projects (SLAV project, RISE); not yet in production. Positioning: S2 operates closer to the device side than OpenADR — it standardizes what a device can do and how to represent its flexibility, while OpenADR standardizes how the signal is dispatched.

IEEE 2030.5 (Smart Energy Profile)

Standard: IEEE 2030.5 Purpose: Two-way communication between DERs, aggregators, and DSOs; designed to handle large volumes of devices. Also called “Smart Energy Profile 2.0.” Swedish status: Limited use; evaluated in research projects. Positioning: Competes with OpenADR in the aggregation layer; stronger in North American markets.

Layer 2 — DER protocols

These protocols communicate between energy management systems and specific device categories (EV chargers, inverters, batteries).

OCPP (Open Charge Point Protocol)

Standard: Open Charge Alliance; Swedish national standard SS-EN IEC 63110 Purpose: Communication between EV charging infrastructure (charge points) and back-office systems (charge point operators) Swedish status: Extensive use — the dominant EV charging protocol in Sweden and globally Versions: OCPP 2.x introduces smart charging and bidirectional (V2G) support V2G service lifecycle role: OCPP operates at two distinct stages in V2G service delivery: (1) Installation/Configuration — remote EVSE setup and configuration by the Aggregator after physical installation; (2) Usage — ongoing delivery of V2G schedules from the Aggregator’s Central Management System to the charger, meter value reporting, firmware updates. This dual role distinguishes OCPP from ISO 15118, which is a Usage-only protocol. (Source - Malakhatka et al V2G Service Blueprint Sweden (2026)) Cross-reference: Villkorade Avtal — CPOs are the primary users of conditional connections; OCPP is the protocol stack on which OpenADR sits for EV-side implementations

ISO 15118

Standard: ISO/IEC Purpose: Communication between EV and charging station (vehicle-side); enables Plug & Charge (automatic authentication) and Vehicle-to-Grid (V2G) bidirectional power flows Swedish status: Expected to grow with V2G deployments; not yet widespread Regulatory driver: EU alternative fuels regulation and V2G policy are pushing ISO 15118 adoption V2G service lifecycle role: operates exclusively during the Usage phase — covers EV connection, authentication, and negotiation of charging/discharging parameters (power, energy, duration) directly between the EV and the smart charger. Not involved in the Installation/Configuration phase (that is OCPP’s domain). (Source - Malakhatka et al V2G Service Blueprint Sweden (2026)) Cross-reference: Vehicle-to-Grid — ISO 15118-20 is the enabling standard for V2G at the charging interface

SunSpec Modbus

Standard: SunSpec Alliance; based on Modbus Purpose: Communication with solar inverters, batteries, and DER monitoring/control systems Swedish status: Used in solar, battery, and DER monitoring in Sweden; integrated in IEEE 1547-2018 (the US standard for DER interconnection) Maturity: Established, widely deployed

Matter (versions 1.3 / 1.4)

Standard: Connectivity Standards Alliance (CSA); backed by Apple, Google, Amazon, and major device manufacturers Purpose: Originally a smart home interoperability standard; versions 1.3 and 1.4 (2024) added energy management — solar, batteries, heat pumps, and EV charging are now in scope Swedish status: Emerging — smart home devices with Matter support are entering the Swedish market; energy management capabilities are new as of 2024 Significance: If Matter achieves the smart home market penetration its backers intend, it could become a de facto DER standard for residential devices, potentially displacing device-specific protocols at the consumer end

V2G communication stack across the service lifecycle

Service blueprinting of Swedish V2G (Malakhatka et al. 2026, Vinnova project) maps each protocol to the specific phase of V2G service delivery where it operates: (Source - Malakhatka et al V2G Service Blueprint Sweden (2026))

Key insight from this mapping: the V2G stack requires five distinct protocols across four communication layers — none covers the full chain. An aggregator operating end-to-end must implement all five.

Layer 3 — Local automation protocols

These protocols coordinate devices within a building, home, or premises. They operate between the end device and a local energy management system (HEMS — Home Energy Management System) or building management system.

EEBus

Standard: EEBus Initiative (Germany) Devices: Heat pumps, EV chargers, white goods, HEMS Links: EN 50631, ETSI SAREF4ENER (semantic framework for smart energy) German status: Required under §14a EnWG since 2024 — German network operators must offer smart charging / demand flexibility contracts, and EEBus is the mandated interface. This has driven rapid adoption in Germany. Swedish status: Limited outside Germany — no Swedish regulatory mandate. May gain indirect relevance if heat pump or EV charger manufacturers standardize on EEBus for their German products and deploy the same hardware in Sweden.

SG Ready

Standard: Bundesverband Wärmepumpe (German Heat Pump Association) Purpose: Simple 2-bit signal to heat pumps (four modes: locked out / normal / boosted / compulsory-on) German status: Prerequisite for state subsidy for heat pumps in Germany (Bundesförderung für effiziente Gebäude) Swedish status: Limited — some heat pumps sold in Sweden include SG Ready ports, but no Swedish regulatory framework uses the signal

PowerMatcher

Origin: Netherlands (ECN/TNO) Purpose: Software framework for agent-based energy balancing within a local cluster Status: Minor; research/pilot use

Thread

Purpose: Low-power mesh networking protocol; underlying communication layer for Matter and IoT devices Status: Infrastructure, not directly relevant at the flexibility application layer

Layer 4 — Grid and critical infrastructure protocols

These protocols are used by DSOs and TSOs for substation automation, SCADA, and control centre communications. They are typically not relevant to aggregators or end-user devices.

IEC 61850

Standard: IEC Technical Committee 57 Purpose: Substation automation, protection relays, SCADA communication for DSO/TSO operations Scope expansion: IEC TC 57 is actively extending IEC 61850 data models to represent DERs (batteries, EV chargers) — bringing grid infrastructure communication standards into contact with the flexibility layers above Swedish status: Standard for DSO/TSO substation operations in Sweden and across Europe

DNP3

Purpose: Communication between control centres and field equipment (RTUs, IEDs); common in North American utilities Swedish relevance: Less common in Europe; IEC 60870-5-104 generally preferred

IEC 60870-5-104

Purpose: Control centre to substation communication over TCP/IP; essentially the European parallel to DNP3 Swedish status: Standard in Sweden and across European DSO/TSO operations

EU regulatory pipeline — the two-pillar structure

The regulatory framework for flexibility communication has two separate pillars, often confused:

Pillar 1 — Network Code on Demand Response (NC DR): defines the market rules for flexibility — how resources register, qualify, and participate in markets. NC DR explicitly does NOT mandate technical protocols or data formats. This is a deliberate separation.

Pillar 2 — Implementing Act under EMD Art. 24: a separate EU implementing regulation specifically for demand response protocols and data formats. The Commission’s Citizens’ Energy Package (COM(2026)115, Actions 5 and 6) sets the timeline as 2027 — both the energy sharing data interoperability regulation and the flexibility retail contract interoperability regulation are expected as a single Implementing Regulation on interoperability requirements. Earlier estimates had put this at 2026; the 2027 date is now the Commission’s stated plan. This is the instrument that will mandate which technical protocols are required for flexibility market participation and for energy sharing operationalization. (Source - Citizens Energy Package COM(2026)115)

A first Implementing Act under EMD Art. 24 (covering metering data access) was adopted in 2023. The DR/energy-sharing-specific Implementing Act is the next in the pipeline.

Implication for Sweden: OpenADR‘s position as the Swedish industry standard puts Sweden in a strong position for compliance with the Art. 24 Implementing Act — provided the final act aligns with OpenADR, which is the most likely outcome given its IEC standardization and EU-wide uptake. However, the outcome is not guaranteed until the Act is published.

Standardization bodies feeding into EU regulation:

• IEC TC 57: extending IEC 61850 for DER representation (feeding into grid infrastructure requirements)
• IEC TC 69: finalizing ISO 15118 series for V2G (feeding into EV-specific mandates)
• EDNA (IEA 4E program): international mapping of device flexibility potential and policy comparison; Energimyndigheten participates; results expected early 2026
• CEN/CENELEC/ETSI COG SG (Coordination Group Smart Grid): coordinates EU smart grid standards across the three major European standards bodies

Swedish challenges

Sweden faces specific barriers to a coherent protocol landscape:

• ~170 DSOs with heterogeneous legacy systems — fragmentation makes standardization harder than in countries with one or two large DSOs. Each DSO may implement the same standard differently, as the E.ON vs Ellevio OpenADR divergence illustrates (Source - Energiföretagen Supplement Conditional Grid Connections (2025))
• Regulatory uncertainty: LFM-h/p/e (local flexibility market — heating/production/EVs) product specifications submitted to Ei in March 2025 — still pending as of late 2025. Protocol choices depend partly on regulatory product design
• Skills shortage: implementing and maintaining flexibility systems across 170 DSOs requires expertise that is scarce
• Proprietary lock-in: legacy investments in vendor-specific systems create switching costs and resist standardization
• Open protocols as a security measure: the cybersecurity risk from large numbers of connected DERs (§3.1 analysis) is reduced when open protocols are used — they distribute security responsibility and reduce single-vendor attack surfaces. Proprietary protocols concentrate vulnerability
• Effektavgift fragmentation as automation barrier: each DSO designs its effektavgift differently, making standardised automated control integration costly — a control service must implement different logic per DSO. Ei has officially confirmed this barrier: in the March 2026 government assignment on a new effektavgift model, Ei division head Tommy Johansson explicitly cited fragmented DSO models as an obstacle to automatic steering services development. This is now the primary stated regulatory driver for the forthcoming harmonized effektavgift framework. (Source - Ei Effektavgifter Uppdrag (2026))

Cross-references

• OpenADR — the Swedish/EU DSO-side market layer standard in detail
• Villkorade Avtal — primary current use case for OpenADR in Sweden
• Network Code on Demand Response — market rules framework (Pillar 1); FIS data exchange requirements
• Energy Storage — DER protocols relevant to batteries (SunSpec Modbus, Matter, IEC 61850 extensions)
• Demand Response — synchronisation risks that protocol design needs to address (random startup delay)
• Ei — regulatory authority for the Swedish flexibility protocol landscape; developing föreskrifter for DSO–customer communication
• Distribution System Operator — 170 heterogeneous Swedish DSOs as the fragmentation problem
• Source - Svk EMDO BASE Ontologier (2026) — a different layer from the protocols above: Svk’s EMDO/BASE RDF ontologies are a semantic data-model for electricity-market data (reserve products, bidding zones, auction rounds…), defining what data means rather than how signals are dispatched; relevant to the DHV/FIS data model (Elmarknadshubb)

Data gaps

• Whether the Art. 24 EMD Implementing Act (DR-specific) will mandate OpenADR specifically or a technology-neutral performance standard
• EEBus adoption trajectory in Sweden — will German §14a EnWG drive cross-border harmonisation?
• S2 adoption outside the Netherlands — any Swedish production deployments?
• EDNA results (early 2026) — how does Sweden compare internationally on device-level flexibility readiness?
• Whether Ei’s new föreskrifter for DSO–customer communication will create protocol mandates ahead of the Art. 24 IA