Joulen Flex: A New Revenue Stream from Every Battery, EV and Heat Pump You Install

Battery storage installations alone hit a record 36,000 systems in the UK in the first half of 2026, an 80% increase vs H1 2025. Most of that value stops at the meter.

Home batteries, EV chargers and heat pumps are already cutting bills through time-of-use tariffs. Far fewer are earning a second income by trading their spare flexibility into the energy market, because until recently, almost nobody outside a licensed electricity supplier could.

That's changing. And it's opening a new revenue line for installers who know where to plug in.

The market enablers behind the shift

Market regulations now allow registered Virtual Trading Parties to trade consumer flexibility, regardless of who supplies electricity to the site. Batteries, EVs and heat pumps no longer need to sit idle between charge cycles.

Why this matters now:
36,000 battery systems installed in the UK in H1 2026, an 80% increase vs H1 2025
(MCS/DESNZ) ~80% of GB sites are expected to move to half-hourly settlement by October 2026, a pre-requisite for participating in trading. Most of that installed base is still monetised through bill savings alone, leaving market revenue unclaimed For installers, this is the gap Joulen Flex closes.

Introducing Joulen Flex
Joulen already trades more than 1GWh of flexible capacity every week, as a registered Elexon Virtual Lead Party and Virtual Trading Party. Joulen Flex puts that infrastructure behind installers. Joulen Flex is a fully managed flexibility service for installers and their customers' batteries, EVs and heat pumps. It runs like a control room and trading desk, delivering a new cash flow for your portfolio of flexible assets.

Four things happen behind the scenes:

Installers plug in; Joulen runs the rest.

What it's worth
Joulen optimises across two separate cashflows. Tariff optimisation reduces the endcustomer's bill through import reduction and export tariffs, already common practice across the market. Market trading adds a second, separate payment from Joulen, built on
wholesale trading, Capacity Market payments, and grid services. That second cashflow needs a specific energy market licence to access it. Joulen holds this licence and can use it to deliver new revenues to installers.

On typical assets, that translates to real annual payments:

Why installers are choosing Joulen

You keep the customer — Joulen sits behind the scenes and never competes for the end-customer relationship

Already licensed and live — trading thousands of sites today, not a roadmap promise

No capex, no build — no need to spend on building a trading desk, aggregation or dispatch platform

Commercials that fit you — typically a revenue share, with flexibility to adjust based on risk-appetite

Joulen Flex already supports major OEMs including: Fox ESS, Solis, and SolaX, and
integrates with Zervio Orbit for C&I sites.

Ready to add a new revenue line to your installs?

Get in touch here to request a call and talk through your install volumes, hardware brands and target go-live.