Why VPPs need a home energy manager behind them

Every balance responsible party (BRP) settles its imbalances quarter hour by quarter hour. When its customers produce more than planned, the BRP pays for the difference at the imbalance price. On a sunny day with hundreds of rooftop PV systems in the portfolio, that difference adds up quickly.

The flexibility to fix it already sits in the portfolio. The BRP can turn production down in its customers’ homes, right when the imbalance happens. We call this BRP Flex.

Curtailing a PV system is never free for the household. If the house is using electricity at the time, it has to buy that power from the grid instead of using what its own solar panels produce. And if the home is exporting to the grid, there is lost production revenue. A VPP that can only turn solar panels on and off can’t see that cost. Fever Energy can, because we already optimise each home, planning around its consumption, tariffs and prices. That is how you get the full value out of flexibility.

How BRP Flex works with Fever Energy

Fever Energy runs BRP Flex on the same platform that optimises each home. That means every activation is decided with the household’s economics in view, not added on top of them.

Predict what’s available. Fever Energy forecasts the PV production of every participating home and turns it into a schedule of capacity the BRP can call on. The forecast updates through the day as real production data comes in.

Price every home. Because Fever Energy optimises each home both behind the meter (self-consumption, spot prices, grid tariffs) and in front of it (balance and energy markets), it knows what a curtailment would cost each household right now. The BRP sees that cost per home and for the portfolio as a whole.

Activate only where it pays. When the BRP calls for flexibility within a quarter hour, the platform splits the request across the homes where curtailing is net positive: where the imbalance cost the BRP avoids is larger than what it pays to reimburse the household. Homes where it would cost too much are left out, and a home that reaches its cost ceiling is taken out of the schedule.

Report what was delivered. After each activation, the BRP gets a delivery report: how much energy was curtailed, where, and what it cost the homeowners. That gives the BRP what it needs to settle and to share value back with its customers.

The result is curtailment that only happens when there is a net gain for both the BRP and the household. It also runs alongside the platform’s other PV controls, such as curtailing at negative prices, so the two never work against each other. The BRP Flex interface is asset-agnostic: it starts with solar, and home batteries can join the same pool.

Case study: Varberg Energi

Varberg Energi has used Fever Energy since 2023 and runs its residential and commercial portfolios on the platform. Its aggregation and VPP functionality gives Varberg Energi real-time visibility of the production from its customers’ PV systems.

“When the intraday market closes an hour before the delivery quarter, the only tool we have, if an updated forecast shows we’re heading for an imbalance, is to control flexible energy resources.”

Jens Nordberg, Head of Energy Trading, Varberg Energi

Fever Energy helped Varberg Energi use that solar to reduce its imbalances, but only in the homes where a curtailment was net positive for the household too. That meant knowing the opportunity cost of every activation, for every home, before acting.

BRP Flex went live in May 2026 in SE3. Over July and August, Varberg Energi activated it on 288 separate occasions:

• 288 activations of 15 minutes (189 in July, 99 in August)
• 24 days with activations (16 in July, 8 in August)
• 72 hours curtailed (47.3 in July, 24.8 in August)
• 51 MWh of energy delivered (18.9 in July, 32.0 in August)

The busiest moment came on 2 August, when 408 homes curtailed about 2.7 MW between 13:15 and 14:30. The busiest day was 8 August, with 27 activations from 06:15 to 17:30. Across the summer, that added up to around 66,000 individual curtailments, coordinated in groups of about 230 homes at a time.

The cost to homeowners came to about €32 per MWh curtailed. Because it was calculated for every home and every activation, Varberg Energi could weigh it against the imbalance cost it avoided, and knows exactly what to share back with the households that took part.

“We know that every time, we’ve at least covered the cost we create.”

Jens Nordberg, Head of Energy Trading, Varberg Energi

Varberg Energi now plans to expand BRP Flex to include more homes and assets.

Flexibility you can act on

Most VPPs can switch assets off. Fewer can tell you what that costs the person who owns them. That is the gap between flexibility that exists on paper and flexibility a BRP can use every day without putting its customer relationships at risk.

We call it actionable flexibility. For Varberg Energi, it means lower imbalance costs. For the grid, it means less surplus solar in the wrong quarter hour. For the homeowners, it means curtailment that never leaves them out of pocket.

“A VPP that can only switch solar panels off isn’t enough. To use flexibility every day, you need to know what each activation costs the home it happens in. Because we already optimise every home, we can give the BRP that answer in real time and make sure the household comes out ahead every time.”

Jonatan Raber, CPO, Fever Energy

Want to see how BRP Flex would work in your portfolio? Talk to us.