From connections queues to connected homes: why firm flexibility beats ‘fingers-crossed’ flexibility

Demand on local distribution networks is rising sharply. Electric vehicles, heat pumps and digital demand all add load. Meanwhile, the UK’s clean energy mission means more generation within our communities – rooftop solar, home batteries, community projects – creating new patterns of supply and demand that the electricity system was never originally designed to manage.

By the mid‑2030s, large numbers of local substations are expected to reach capacity. Network reinforcement will be needed but it is expensive, complex and ultimately paid for by consumers through network charges on their bills.

The impact of these non-energy costs on bills is a growing concern, and is covered in our post here: https://news.eonenergy.com/news/paying-fairness-smart-support-unlock-affordable-lowcarbon-homes

Part of this approach is helping network operators to play their part in a fairer energy transition – using flexibility not only to support our local grids but also to prioritise fuel poor customers.

A knock-on effect already is that across the UK thousands of clean‑energy projects are waiting longer than expected for grid connections. While transmission‑level queues dominate headlines, local networks are also facing pressure points: substations reaching their limits, circuits running hot, and reinforcement works taking months or years to schedule.

But there is a solution that doesn’t involve building our way out of every constraint: firm, targeted flexibility deployed exactly where the grid needs it.

Why the connections challenge is growing

Local grids were built for a different era, one in which electricity flowed one way and neighbourhood demand grew slowly and predictably. Today, the picture is entirely different. Rapid electrification of heat and transport is pushing up peak demand, while distributed generation introduces new flows of power in and out of the network. All of this creates congestion in places that historically never saw it.

Distribution Network Operators (DNOs) are upgrading assets as quickly as possible, but supply chains, labour constraints and practical engineering limits are real. In recent years, underspend against capital budgets has reflected these bottlenecks: in some cases transformers are on 18‑month lead times, and cable crews are in short supply.

The result is that new connections often cannot proceed until reinforcement is completed – creating queues, delays and uncertainty.

The opportunity: firm flexibility for specific locations

Flexibility already exists in the UK through voluntary, commercial or time‑of‑use programmes. But the types of flex that help the transmission system do not always help a specific local substation.

What DNOs really need is firm, predictable, and locally‑deliverable flexibility – assets that will always be available, at the right time and at the right node of the network.

This is exactly what E.ON’s proposal is demonstrating.

How it works

The concept is simple. In neighbourhoods where the local substation is coming under pressure, E.ON can install dedicated, grid‑supporting batteries directly into homes. These batteries are not used solely for customers to store their own energy and take advantage of low price periods; they are allocated primarily for DNO needs. That means they can discharge when the grid needs help and charge when it needs relief.

At other times, the batteries help the wider electricity system by buying and selling power when it’s cheapest or most useful. The money they make from this helps lower bills for the households that have them.

Because the batteries are prioritised for use by the DNO, they can provide something the wider flexibility market often struggles with: certainty.

Benefits for the grid

For DNOs, batteries provide a block of flexible capacity exactly where it is needed. With dozens or hundreds of these batteries installed in a single ‘constraint zone’, they can support growing demands for power available at specific substations which might otherwise struggle. That enables:

• Earlier connections for homes and local projects.
• Strategic timing of reinforcement, reducing costs.
• Reduces the need to curtail renewables when there’s too much power or too little demand – at the time helping to manage supply and demand on low voltage networks
• Avoids need for temporary diesel generators (which are still sometimes used during planned outages).
• Better resilience during unexpected faults or localised power cuts.

This is flexibility as infrastructure, but at a fraction of the cost of traditional reinforcement.

Benefits for the wider system

When the batteries are not supporting the local grid, they can participate in wider system balancing, reducing the costs which we estimate can be as much £50 million a year. They also support the UK’s target to reach 10GW of consumer‑led flexibility by 2030 by bringing reliable, low‑barrier storage into the system.

And because these batteries are targeted at constrained areas, the value they deliver is amplified: one kilowatt of flexibility in the right place is worth substantially more than the same kilowatt in an unconstrained area.

Grid constraints often feel like an engineering issue. But in reality, they are a people issue: rising bills, slower connections, and delays to decarbonisation. Firm flexibility connects the dots between households, networks and system operators – turning constrained neighbourhoods into active participants in the energy transition.

The connections queue doesn’t have to define the pace of UK decarbonisation. With the right tools in the right places, we can move from queueing… to connecting.

You can download our full report on the role batteries can play in supporting networks and driving more affordable energy here