TNUoS 2026: Why Grid Charges Rise and How Solar Hedges Them

If you run a warehouse or logistics operation, you have probably noticed that the unit rate on your electricity bill keeps drifting up even when the news says wholesale gas and power prices are falling. That gap is not a mistake. A growing share of what you pay for each kilowatt-hour has nothing to do with the commodity price of electricity at all. It is the cost of the network that delivers it, and one of the biggest of those network charges is set to jump by roughly 60% in April 2026.

This guide explains, in plain English, what TNUoS and BSUoS are, why the non-commodity part of your bill is rising, and why a warehouse solar array sized to your daytime load is one of the few things that actually hedges you against it.

What you are actually paying for on a commercial electricity bill

It helps to stop thinking of your bill as one number and start thinking of it as a stack of layers. Only one of those layers is the electricity itself.

The commodity cost is the wholesale price of the energy: the bit that goes up and down with global gas markets and headlines. Everything else is non-commodity: charges bolted on top that fund the physical system delivering power to your meter, plus policy costs and supplier margin. On a typical commercial contract the non-commodity portion can be roughly half of the delivered unit rate, and it has been climbing steadily.

Two of the most important non-commodity charges are TNUoS and BSUoS.

TNUoS in plain English

TNUoS stands for Transmission Network Use of System. It is the charge that pays for the high-voltage transmission network: the pylons and substations that move electricity long distances from where it is generated to your region. Think of it as the toll for using the motorway network of the grid. Everyone connected to the system contributes, and the charge is recovered through your supplier and passed on inside your unit rate or as a separate line item, depending on your contract.

BSUoS in plain English

BSUoS stands for Balancing Services Use of System. The grid operator has to keep supply and demand matched second by second, every second of the day. That balancing work costs money: paying generators to turn up or down, managing constraints, holding reserves. BSUoS is how that cost is recovered. It is the running cost of keeping the whole system stable, and like TNUoS it lands on your bill on top of the commodity price.

Neither charge buys you a single extra electron. They are the cost of the delivery system. And crucially, they are charged per unit of electricity you import from the grid.

Why the network portion is rising

The network is being rebuilt and expanded at the same time. The UK is connecting large volumes of offshore wind, reinforcing ageing infrastructure, and building new transmission capacity to move power from where it is generated to where it is used. That investment is real, it is necessary, and it is recovered from network users through charges like TNUoS.

The headline for warehouse operators is blunt: TNUoS is set to rise by roughly 60% in April 2026. That is a material increase to the delivered cost of every imported unit, and it is largely insulated from whatever the wholesale market is doing. Even if commodity prices fall, this layer of your bill is going up. For a business running forklift charging, refrigeration, extensive lighting, automation, or conveyor lines across a large roof footprint, that rise compounds across a big annual consumption.

The uncomfortable takeaway is that the part of your bill you have least control over is the part growing fastest, and it is tied directly to how much power you pull from the grid.

How self-consumed solar hedges the rise

Here is the mechanism, and it is simpler than it sounds.

TNUoS and BSUoS are charged on imported units. A rooftop solar array generates electricity on-site. Every unit your building consumes directly from the panels is a unit you did not import. That means it avoids the full delivered cost: not just the commodity price, but the network and policy charges stacked on top of it, TNUoS included.

This is the point most bill-reduction pitches miss. A self-consumed solar unit is not worth the wholesale price of electricity. It is worth what you would otherwise have paid all-in for an imported unit. As TNUoS climbs, that all-in avoided cost climbs with it, so the value of every self-consumed unit goes up automatically. Solar is one of the few investments that gets more valuable as network charges rise, because it is a hedge against precisely the layer of the bill that is growing.

Warehouses are unusually well suited to this. The consumption profile is largely daytime and largely flat, which lines up neatly with the solar generation curve. An array sized to your daytime load will typically self-consume 60-75% of what it generates, and for a genuine 06:00-18:00 operation that figure can reach 90%+. High self-consumption is the whole game, because self-consumed units carry the full hedge while exported units do not.

Exported units, by contrast, earn only a supplier-set Smart Export Guarantee (SEG) rate: anywhere from a few pence to around 15p per unit, entirely at the supplier’s discretion. That is why the strategy for a warehouse is to size the array to daytime demand and consume nearly all of it, not to build the biggest possible system and sell the surplus cheaply.

To get the sizing right you need 12 months of half-hourly (HH) consumption data. That data shows your true daytime load shape, so the array is matched to what the building actually uses rather than to roof area. Our companion guide on sizing warehouse solar from half-hourly data walks through exactly how that works.

An illustrative before-and-after

The table below is illustrative and uses indicative figures to show the mechanism, not a quote for your site. It compares the delivered cost of an imported unit before and after the network-charge rise, and shows why avoiding imported volume is the lever that matters. Your real numbers depend on your contract, region, and load profile.

Cost layer (per unit imported)	Before Apr 2026 (indicative)	After Apr 2026 (indicative)
Commodity (wholesale)	14p	14p
TNUoS + other network charges	8p	~13p (up ~60% on the network element)
Policy, levies, supplier margin	4p	4p
Delivered cost of an imported unit	~26p	~31p
Value of a self-consumed solar unit	~26p avoided	~31p avoided

The commodity price has not moved in this example, yet the delivered cost of every imported unit rises because the network layer climbs. A self-consumed solar unit avoids the whole stack, so the amount it saves you rises in lockstep. That is the hedge: the worse network charges get, the more each on-site unit is worth.

Now scale it. A warehouse importing a large annual volume from the grid feels that per-unit rise across every single unit. Replacing a meaningful slice of that import with self-generated power removes those units from exposure entirely, and keeps them removed for the 25-year-plus life of the panels.

Adding a battery to sharpen the hedge

Solar alone hedges your daytime import. A battery (BESS) extends the hedge in two ways. First, it stores surplus midday generation and releases it into early-morning or evening operations, lifting self-consumption above what a solar-only system achieves. Second, it can charge from the grid during cheap, low-demand periods and discharge during expensive peak periods, shaving your exposure to peak-time network and capacity charges.

A battery is not essential to benefit from the TNUoS hedge, and it changes the payback maths, so it should be sized against your actual load shape rather than added by default. But for operations that run into the evening or start before sunrise, it is worth modelling. Our savings calculator gives a first-pass view of the difference.

What a warehouse system costs, and the tax treatment

Indicative 2026 pricing runs from roughly £850-1,100/kWp for a 100 kW installation down to about £650-850/kWp at 1 MW, where scale brings the unit cost down. Self-funded payback typically lands in the 3-6 year range, driven mainly by how much of the generation you self-consume. Higher self-consumption means faster payback, which is why load-matched sizing matters so much. There is a fuller breakdown on our cost page.

The tax treatment has some traps worth knowing before you budget:

• Annual Investment Allowance (AIA) gives 100% first-year relief on qualifying plant up to £1m of spend, which most warehouse installs sit within.
• Full expensing does not apply to solar. Solar assets fall into the special-rate pool, so they are excluded from the full-expensing regime. Do not assume the headline full-expensing rate applies here.
• VAT at 20% is reclaimable for a VAT-registered business. There is no 0% rate on commercial solar, so budget on the standard-rate basis and reclaim through your normal VAT process.

Always confirm the specifics with your accountant, as your position depends on your company structure and other capital spend in the year.

Where this matters most

The hedge is strongest wherever daytime load is highest and most consistent. Ambient and general storage operations with long lit hours and steady handling equipment convert a large share of generation on-site. E-commerce fulfilment operations, with automation, packing lines, and extended shifts, tend to have some of the flattest and highest daytime profiles of any warehouse type, which makes self-consumption, and therefore the TNUoS hedge, especially valuable.

Location matters too, because TNUoS carries a regional element. Major logistics clusters such as Felixstowe sit at the sharp end of both rising consumption and network investment, so the case for cutting imported volume is particularly clear there.

If any of the terms in this guide were new to you, our glossary defines TNUoS, BSUoS, SEG, self-consumption, and the rest in one place.

The bottom line

Network charges are the fastest-growing, least-controllable part of a warehouse electricity bill, and TNUoS rising by roughly 60% in April 2026 makes that worse. You cannot negotiate the network charge away, but you can reduce the number of units it applies to. Self-consumed solar avoids the full delivered cost of every unit it replaces, so as network charges rise, the value of your own generation rises with them. That is a genuine hedge, not a bet on wholesale prices.

The right next step is to size a system against your real half-hourly data so you know your likely self-consumption, payback, and hedge before committing to anything. Request a quote and we will model it against your actual load profile.