Last-Mile Depots: Solar panels for logistics

Why last-mile depots are a fast-growing case for solar panels for logistics

Last-mile depots are a smaller but increasingly important part of the solar panels for logistics story, and their defining feature is the van fleet. As parcel and grocery operators electrify their delivery vehicles, the depot gains a large new daytime electrical load in the form of EV charging, and that load lines up beautifully with solar generation. Vans charge while they are parked between rounds, often through the middle of the day, which means depot solar can be absorbed at close to 100% self-consumption when paired with fleet charging. For an operator electrifying a depot network, on-site generation turns the charging bill from a new cost into a hedge against rising grid and network charges, which is precisely the kind of controllable saving a logistics business wants when TNUoS and BSUoS keep climbing.

Many last-mile depots also sit within national programmes run by the likes of Royal Mail, Evri and DPD, where decarbonisation targets are set centrally and rolled out site by site. That makes the depot roof a strategic asset rather than an afterthought, even though the buildings are smaller and the urban setting can make planning a little more involved than on a rural distribution site. Where a DC trades on sheer roof scale, a last-mile depot trades on the tight synergy between rooftop generation and the EV fleet charging beneath it, and that combination, together with central net-zero commitments flowing down from programme owners, is why depot solar is one of the fastest-growing parts of the sector.

The fleet-charging angle changes the economics in a way that is easy to underestimate. On a conventional building, solar competes against a relatively modest daytime baseload, so there is a ceiling on how much generation the site can usefully absorb. Add an electrifying van fleet and that ceiling lifts sharply: a few dozen vans charging between rounds can absorb a whole rooftop array on its own, turning what would have been exported surplus into displaced grid import at full price. For an operator facing both rising electricity costs and the capital pressure of fleet electrification, pairing the two means the solar helps pay for the chargers and the chargers raise the value of the solar, which is a far stronger position than tackling either in isolation.

What a typical install looks like and how we size it

For a last-mile depot we usually design a system in the 100 to 400 kW range, roughly 185 to 740 panels over about 600 to 2,400 square metres of roof. A system that size generates in the region of 92,000 to 370,000 kWh a year and saves between 21 and 85 tonnes of CO2 annually. Sizing is driven by the combined baseload of the building and the EV charging schedule, so we pull half-hourly meter data and overlay the charging profile of the van fleet, because the two together define what the site genuinely draws across the day.

A typical depot install pairs the PV with 6 to 24 charge points, and where vans charge predominantly during daylight the array can be sized confidently for self-consumption, knowing the generation will be soaked up by the fleet rather than exported. Where charging shifts to overnight, we assess whether a battery to store midday output or measured export under the Smart Export Guarantee improves the return. Because urban depot roofs are smaller, getting the sizing right matters more than on a sprawling DC; an array matched to the charging schedule pays, while an oversized one on a daytime-quiet depot simply spills cheap export.

Costs, payback and tax relief

A last-mile depot project typically runs £90,000 to £340,000 with a simple payback near 5.5 years, after which the generation is effectively free for the remaining life of the system. The 100% Annual Investment Allowance lets most operators write off the full cost against profit in year one, worth up to a quarter of the value back as tax saved for a limited company, and because depot installs typically sit well below the £1m cap the relief is usually claimed in full in the first year, which is one of the simplest tax positions in the whole logistics sector.

The Smart Export Guarantee pays for any surplus, which matters most for depots that are quieter in the daytime when the vans are out on their rounds. The choice between owning the system and a PPA tends to follow the lease: ownership captures the full allowances and every kilowatt-hour of saving, while a PPA removes the capex and the lease risk for an operator on a shorter urban lease. Our cost guide works through depot-scale numbers and the combined PV-and-charging economics.

Funding routes in detail

For depots the headline route is the Annual Investment Allowance, with most installs fully expensed in year one, and ownership through cash or asset finance keeping every kilowatt-hour of saving. Where a depot is leased, the Green Lease Clause and tenant capital recovery route, supported by the Building Better Partnership Green Lease Toolkit, makes tenant solar possible, and we provide the lease addendum aligned with that standard.

A PPA can suit an operator on a shorter urban lease, shifting the capital and lease risk to the third-party owner who then sells the generation back below grid retail. Depots inside a Freeport or Investment Zone may qualify for 100% Enhanced Capital Allowances on new plant and machinery, so we check the location against the designated zones. The Industrial Energy Transformation Fund rarely applies to pure last-mile logistics, as it targets industrial and food processing rather than parcel handling. Because depot installs are smaller and the tax relief is usually claimed in full in the first year, the funding decision is generally simpler than on a large distribution centre, and for many operators an outright purchase under the Annual Investment Allowance is the cleanest route. The funding page sets out each option in detail.

Compliance and sector considerations

The defining sector consideration for depots is the urban setting, where planning is generally more involved than on a rural distribution site, even though most rooftop PV still falls under Permitted Development through Class A Part 14 of the GPDO 2015. The second is the EV charging infrastructure, which must be designed alongside the PV rather than bolted on afterwards, so that the charging schedule, the array output and the grid connection all work together as a single system rather than three separate projects competing for the same capacity.

Beyond that the standard logistics requirements apply: LPC sprinkler clearance standards govern any sprinklered building, insurer pre-design review is carried out as standard, and wind loading follows BS EN 1991-1-4. A G99 grid application applies above 17 kW per phase, and the combined PV and charging load makes early DNO engagement especially important on a constrained urban network, because the charge points alone can demand significant capacity. Getting the connection right at the start avoids a situation where the array is sized to the roof but the grid will not accept the export or the chargers, which on a tight urban supply is a genuine risk rather than a theoretical one. We carry MCS commercial certification, NICEIC, RECC and TrustMark accreditation along with the ISO 9001, 14001 and 45001 standards, so a programme owner can be confident every depot in the rollout is delivered to the same accredited standard.

How we approach this kind of project

We start with your half-hourly meter data and the charging profile of the van fleet, because on a depot the EV load is what makes solar panels for logistics pay, and the PV and charging design have to be developed together. We engage the local authority early given the urban planning context, complete the roof and structural checks, submit the G99 grid application alongside the structural survey to start the connection clock, and run insurer pre-design review before fabrication.

The proposal is fixed-price, the work carries an insurance-backed workmanship warranty, and the install happens above your operation so van movements and sortation continue; the only outage needed is the final grid synchronisation, scheduled for a quiet window. Urban depots are tight, busy sites, so we plan deliveries, lifting and parking around your daily van movements rather than expecting the operation to make room for us.

Where the depot is part of a national programme run by a parcel or grocery operator, we design to the central decarbonisation specification so the site fits the wider rollout and the data reports cleanly into the programme owner's net-zero tracking, which keeps each depot consistent with the rest of the national estate. Because depots are numerous and broadly similar, a proven design template repeated across the network is far more efficient than treating each site as a one-off, and we build the first depot with that repeatability in mind so the chargers, the array and the monitoring follow the same pattern from one site to the next. That is how a depot-by-depot programme of solar panels for logistics is delivered at the pace a national rollout demands.

An illustrative example

As an illustrative composite based on typical UK depot projects: a last-mile parcel depot electrifying its van fleet installed around 300 kW across the roof, roughly 555 panels generating in the region of 280,000 kWh a year, paired with a bank of charge points for the vans. With charging concentrated in daylight hours between rounds, much of the generation was absorbed on site at high self-consumption, the qualifying cost was written off under the Annual Investment Allowance, and the depot's charging bill became a hedge against rising network charges rather than a new fixed cost. The figures are illustrative and depend on your fleet, charging pattern, roof and tariff.

Last-mile depots are where solar and fleet electrification meet most neatly, and if your network also runs larger sortation or chilled sites those buildings carry strong cases of their own; see fulfilment centre solar and cold storage warehouse solar for how the numbers change at scale. When you are ready, review the cost guide and funding routes, then request a free feasibility from your meter data or read the logistics solar FAQs.