CheckWatt

CheckWatt AB is Sweden’s largest residential battery aggregator and the leading independent aggregator in the Nordics. Founded in Gothenburg in 2017, it operates a Virtual Power Plant comprising 15,000+ customer sites across Sweden and Finland, delivering ancillary services to TSOs and local flexibility to DSOs. It is the clearest real-world example in Sweden of multi-market value stacking and the B2B2C aggregator business model at residential scale.

Overview

CheckWatt describes itself as “Nordens ledande oberoende aggregator” (the leading independent aggregator in the Nordics). It aggregates residential and commercial battery systems — along with EV chargers and some flexible consumption — into a virtual power plant that participates simultaneously in Balancing Markets and local Flexibility Markets. (Source - CheckWatt Website (2025-2026))

Services

Ancillary services

CheckWatt delivers the following services to TSOs (Svenska kraftnät in Sweden, Fingrid in Finland):

The FCR-D market milestone — 100 MW by summer 2024 — represents approximately one-fifth of Sweden’s total FCR-D procurement volume, making CheckWatt the largest single portfolio in that market. (Source - CheckWatt Website (2025-2026))

Local flexibility

CheckWatt delivers local flexibility to DSOs during periods of grid constraint, typically cold winter days:

• Effekthandel Väst (Göteborg Energi Elnät + Mölndal Energi Elnät) — largest portfolio; the ~1,000-battery figure is CheckWatt’s combined total across E.ON Switch and Effekthandel Väst together for winter 2025/26 (Effekthandel Väst’s own share is likely lower, roughly ~600 given E.ON Switch’s separately stated ~400)
• E.ON Switch (multiple zones) — ~400 battery systems, ~8 MW as of January 2026; zones include Bålsta, Hässleholm, Kungsängen, Älmhult-Osby, Örebro, Södra Skåne; no activations in Kalhäll or Bromölla-Sölvesborg in winter 2025/26
• Kinnekulle Energi (Götene) — small scale, direct agreement
• Stockholm Flex — first local flex delivery winter 2022/23 (300 kW battery); market since closed

Approximately 10% of CheckWatt’s Swedish customers live in areas where their DSO procures local flexibility. (Source - CheckWatt Website (2025-2026))

Winter 2025/26 local flex revenues — zone comparison

Compensation for a 10 kWh battery system (winter 2025/26 season):

The large spread reflects grid constraint intensity: Bålsta batteries were activated for 100+ hours; Göteborg/Mölndal for 2–20 hours. The Göteborg and Mölndal figures were well below the ~740 SEK net reported for 2024/25; one change that season is that Göteborg Energi now buys availability weekly instead of seasonally (Mölndal Energi still buys for the whole season), though CheckWatt does not itself attribute the drop to it. (Source - CheckWatt Website (2025-2026))

Behind-meter optimization

The CheckWatt AI system runs in parallel with ancillary service delivery:

• Forecasts household electricity consumption and solar production
• Manages 20–45% of battery capacity for self-consumption and price arbitrage
• Charging/discharging power typically limited to 1–2 kW for CheckWatt AI’s self-consumption/arbitrage operation (not a stated local-flex-specific limit — the local-flex charging constraint described elsewhere is a 20%-of-battery-energy-per-hour limit around a delivery window)
• From October 2025: uses 15-minute quarter-hour prices in newer firmware

Platform and technology

CM10: A proprietary hardware gateway installed by a partner electrician (~1 hour). Connects the battery inverter and energy meters to CheckWatt’s cloud platform. Compatibility lists are continuously updated as new brands are added (a previously stated “~30 manufacturers” figure was actually a historical Summer 2024 snapshot of connected battery systems, not a stated CM10 compatibility spec). Enables type qualification: newly connected residential systems can begin FCR-D and FCR-N delivery from day one without individual prequalification testing.

EnergyInBalance: Web portal (energyinbalance.se) for customers to monitor revenues, savings, system status, and configure operating mode, electricity contract type, grid tariff, and meter/facility ID (anläggnings-ID, required for local flex participation).

CheckWatt AI: AI forecasting and optimization system for behind-meter services. Launched broadly February 2025 after a pilot. Requires the customer to indicate whether they have a quarter-price or hourly electricity contract.

Operating modes

“CheckWatt Optimized” was previously named “Currently Optimized”; “CheckWatt Savings” was previously “Self Consumption.” CheckWatt reports that the Optimized mode generated 2–3× higher returns than Savings mode over H1 2025 for a typical residential battery in SE3. (Source - CheckWatt Website (2025-2026))

Revenue model

Approximate monthly revenues after all fees (illustrative calculation using historical FCR-D prices from the period when FCR-D dominated battery revenues, i.e. before summer 2024 — not necessarily representative of the current, more diversified revenue mix):

Revenue varies month to month. Compensation is paid approximately 60 days after month-end (first payment) or monthly thereafter, reflecting the delay in payment from Svenska kraftnät and the BRP.

Swedish vs Nordic market structure

In Sweden, CheckWatt must work through a Balance Responsible Party (BRP) to bid ancillary services. The BRP charges an additional 5–10% fee on top of CheckWatt’s 20%. This is the consequence of Sweden’s incomplete BSP implementation — the free-standing BSP role (enabling direct market access without a BRP co-signature) is not expected until 2028. See Aggregation › Sweden’s BSP/BRP problem.

In Finland and Denmark, CheckWatt can register directly with Fingrid and Energinet respectively, eliminating the BRP intermediary and the associated fee.

This structural difference is a plausible contributor to the higher revenue multiplier CheckWatt itself reports for Finland (4.0×) vs Sweden (2.5×) relative to basic price arbitrage (a self-reported figure from CheckWatt’s own website, not FlexAbility data), though CheckWatt’s own site doesn’t draw this causal link explicitly — other factors (price levels, market maturity, service mix) could also explain the gap (Source - CheckWatt Website (2025-2026)).

Company milestones

Corporate events

Failed Emaldo acquisition: In a previously announced transaction, Emaldo Group sought to acquire CheckWatt. After approximately nine months of regulatory review, the necessary regulatory approvals were not obtained and the acquisition was abandoned. CheckWatt continues as an independent company. A commercial partnership with Emaldo continues: Emaldo batteries are connected via the CheckWatt platform to ancillary service and local flex markets. (Source - CheckWatt Website (2025-2026))

Role in the Swedish flexibility ecosystem

CheckWatt is the primary real-world case for several structural features of the Swedish flexibility landscape:

1. Aggregator as essential infrastructure: 65% of Swedish home battery owners use an aggregator (Source - FlexAbility Delrapport 4 (2025)); CheckWatt’s portfolio is the largest realization of this pattern.
2. Value stacking: The same batteries simultaneously serve FCR-D (TSO balancing), local flex (DSO congestion), and price arbitrage/solar storage — the Virtual Power Plant model in practice.
3. BRP barrier impact: The 5–10% BRP fee in Sweden illustrates the structural cost of the incomplete BSP role. Finland’s lower barrier structure enables higher net revenue for equivalent resources.
4. Type qualification scale: CheckWatt’s ability to deploy residential batteries at scale (1,000+ per season) without individual prequalification is enabled by the Nordic FCR type qualification pathway for units ≤100 kW.
5. Local flex market demand signal: CheckWatt’s activation data provides the best publicly available evidence of actual grid constraint intensity by zone in Swedish DSO networks.

See also: The Flexibility Provider Base — Structure, Barriers, and the Aggregator Constraint for the aggregator-as-necessary-infrastructure analysis; Effekthandel Väst for the largest local market they participate in; SWITCH for the E.ON platform they bid into.

Related pages

• Aggregation — market role, BRP/BSP structural barriers
• Virtual Power Plant — VPP technology and portfolio model
• Balancing Markets — FCR-D/N, mFRR, aFRR market structure
• Effekthandel Väst — primary local flex market
• SWITCH — E.ON platform for local flex market
• Svenska kraftnät — Swedish TSO counterpart for ancillary services
• Nordic Balancing Model — 15-min pricing and balancing structure
• Energy Storage — BESS technology context
• The Flexibility Provider Base — Structure, Barriers, and the Aggregator Constraint — synthesis