1.4 MW + battery on an e-commerce fulfilment operation

This is an illustrative example based on typical projects - not a real named client. The figures are indicative planning-grade numbers for a representative automated fulfilment operation, not a case study of an identifiable business.

The brief

A national e-commerce retailer runs an automated fulfilment shed of around 350,000 sq ft in the East Midlands “Golden Triangle” - the kind of highly mechanised operation where conveyors, sortation lines and goods-to-person robotics run through most of the working day. Electricity had become the single biggest controllable cost on the site at roughly £1.1m a year, and it was climbing: the TNUoS network element alone was set to rise about 60% from April 2026, applied to every unit imported. The operations director wanted to hedge that exposure and put auditable Scope 3 evidence into the customer sustainability reporting that flows down from major retail partners.

The challenge

The obvious problem was not roof space - there was plenty of clear-span steel-portal roof. The binding constraint was the grid import connection, which was already sitting close to its agreed capacity. Every extra kilowatt of automation and any future EV-van charging pushed the site nearer to its ceiling, and a fresh DNO reinforcement to lift the connection would have been expensive and slow. A naive roof-fill design would also have created a second problem: a large export flow the connection could not accommodate, and a firm export connection is no longer guaranteed under the post-2026 grid-queue reforms.

What the half-hourly data showed

We started, as always, from twelve months of half-hourly (HH) meter data rather than the roof plan. The automation load gave this site a very different profile from a single-shift ambient shed: a steady, high daytime base-load driven by conveyors, sortation and robotics running continuously through daylight hours. Demand also had a pronounced Q4 peak as the site scaled for the peak retail season. That combination - a firm daytime base-load plus sharp seasonal peaks - is exactly the profile where solar self-consumes heavily and a battery earns its keep.

The design

The array was sized to the load, not the roof: a 1.4 MW rooftop system generating about 1,260,000 kWh a year (~900 kWh/kWp on this East Midlands site), matched against the automation base-load so that generation is consumed on site rather than exported cheaply. To fit within the existing connection we used an export-limited (G100) design, submitted early through a full G99 application, so the array could go ahead without waiting on a network reinforcement. A 1 MWh battery was modelled alongside it for peak-shaving - storing midday surplus and discharging into the Q4 evening peaks to shave the most expensive imported units and reduce demand at the times TNUoS charges bite hardest.

Panels were fixed with non-penetrative clip-fix mounting to preserve the roof warranty, and the layout was designed to LPC / RISCAuthority RC62 clearances around sprinkler zones and firewalls, with the insurer’s pre-design sign-off obtained before fabrication. Because the operation is a tenant on a long institutional lease, a BBP-aligned green-lease addendum handled landlord consent so the occupier captured the saving.

The outcome

• 1.4 MW rooftop PV + 1 MWh battery, ~1,260,000 kWh generated a year
• 81% self-consumption - the steady automation load absorbs the great majority of generation on site
• ~£280,000 a year off the electricity bill, hedging both wholesale price and the rising TNUoS network charge
• ~5.2-year payback self-funded (before the year-one tax position)
• Avoided a costly DNO reinforcement entirely, because the export-limited design and battery kept the project inside the existing connection

Solar PV is special-rate-pool plant, so a profitable company writes most of the capex off in year one via the £1m Annual Investment Allowance, with the 50% First-Year Allowance on the balance above £1m - which shortens the effective payback further. The battery and PV plant are also exempt from business rates in England to 31 March 2035. (Commercial solar carries standard 20% VAT, reclaimable by a VAT-registered business.)

Why it matters for similar operators

For automated e-commerce fulfilment operations, the real limit is almost never the roof - it is grid import capacity once robotics, sortation and EV charging are added. The winning move is to design for high self-consumption within your existing connection, use export limitation to sidestep a reinforcement queue, and add storage where a peaky seasonal profile justifies it. Sized to the load and structured around the tenure, a system like this turns the largest unused asset on the site into a compounding hedge against network charges that only go one way. See the indicative cost ladder for systems of this scale, or request a quote built from your own half-hourly data.