Aggregator

An aggregator is a legal entity that pools the consumption or generation capacity of multiple market participants and offers it to the Transmission System Operator as balancing reserves or to the wholesale market as a single bidder. The role is recognised in EU law via Directive (EU) 2019/944 — Article 2(18) defines aggregation, Article 2(19) defines the "independent aggregator" as a market participant not affiliated with the customer's supplier.

Why aggregation exists

Most flexibility lives in small assets — home batteries, EV chargers, heat pumps, behind-the-meter solar — that individually fall below the minimum bid sizes of balancing markets. A BESS under 1 MW typically cannot prequalify for mFRR alone. The aggregator pools many such assets into a single virtual unit; the TSO sees one bidder. The economic value is that the aggregator captures returns small assets cannot reach individually.

How an aggregator operates

Three layers: (1) a contractual layer with each participating asset owner, defining what the aggregator can dispatch and the revenue share; (2) a technical layer — telemetry, communication protocols (OCPP for chargers, Modbus for inverters, IEC 61850 for substations) and a real-time control system that issues setpoints to assets in milliseconds when balancing markets activate; (3) a market layer — BSP licensing, BRP balance agreement, bidding strategies across day-ahead, intraday and reserves.

Volton as aggregator

Volton operates as an aggregator in Estonia: it is a registered BSP at Elering, holds a balance agreement (BRP) with the Estonian TSO, and pools customer-owned heat pumps, batteries, EV chargers and floor heating into balancing-reserve and spot-arbitrage portfolios. The retail product, Volton Home, is the customer-facing layer of this aggregation.