Last-Mile Depots: Solar panels for industrial units

Why a last-mile depot is the industrial unit where solar and EV charging meet

A last-mile delivery depot is a smaller industrial unit than a regional DC, but it has a feature that makes solar unusually compelling: a fleet of electric vans that charge during the day, on the same site, against the same meter. Daytime EV charging absorbs solar at 100% self-consumption, so the synergy between a roof array and a van fleet is close to perfect. Self-consumption is the biggest driver of solar payback, and a depot that charges its vehicles through the day uses what it generates rather than exporting it cheaply. As the parcel sector electrifies, that pairing turns an unremarkable depot roof into a working asset that powers the fleet it serves, and the more of the fleet that goes electric, the better the solar pays.

The pressures are the same as the rest of logistics, scaled to a smaller building. TNUoS and BSUoS network charges have risen 40 to 80% since 2022, and a depot charging an electric fleet feels rising import costs acutely, because adding vehicle charging to a building's load is exactly the kind of demand growth that exposes an operator to those charges. Many last-mile depots are part of national programmes run by operators such as Royal Mail, Evri and DPD, where sustainability and fleet electrification targets flow down to each site, so on-site generation supports both the energy bill and the network-wide net zero commitment. For an operator rolling out EV charging across dozens of depots, solar is the logical companion investment rather than an afterthought, and standardising a solar-plus-charging design across the estate spreads the engineering cost. Treating the two as one programme also avoids the common trap of upgrading a depot's connection for chargers, then having to revisit it again later for solar.

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, which is roughly 185 to 740 panels across 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 somewhere between 21 and 85 tonnes of CO2 annually. On a smaller urban industrial unit the roof is more modest, so we size carefully against the combined daytime load of the building and the EV charging schedule rather than simply filling the available area. We pull your half-hourly meter data and overlay the van charging pattern, because the depot's value comes from matching generation to the charging window.

The charging profile is the design driver. Vans typically return and charge in two waves, after the morning round and overnight, so the depot that charges a meaningful share through the daytime captures the most solar directly, while overnight charging is better served by the grid or, where it pays, a battery. A typical depot install pairs 100 to 400 kW of PV with 6 to 24 charge points, designed together so the panels feed the chargers wherever possible and the building, the array and the vehicles balance through one coordinated distribution design. We model the realistic roof area once rooflights and any shading from neighbouring buildings are allowed for, which matters more on a constrained urban site than on an open distribution park. The honest answer for many depots is that the roof can generate more than the daytime charging window can absorb, so we size to the genuine self-consumption rather than to the panel count the roof could physically hold, keeping the array productive rather than exporting cheaply at midday. Where a battery genuinely shifts more generation into the charging waves, we include it; where it does not earn its keep, we say so.

Costs, payback and tax relief

A last-mile depot project typically lands between £90,000 and £340,000 depending on roof area and system size, at roughly £700 to £900 per kW, with a simple payback near 5.5 years and the electricity effectively free for the fifteen to twenty plus years after that. The biggest financial lever is tax. Solar PV qualifies as plant and machinery, so the 100% Annual Investment Allowance lets most companies write off the full cost against profit in year one, worth up to a quarter of the project value back as tax saved for a limited company, and at depot scale the system cost usually sits comfortably within the annual allowance cap. Because daytime EV charging consumes generation on site, the return is driven by avoided import, which is the strongest position. For any surplus outside charging hours, the Smart Export Guarantee pays 4 to 15p per kWh as of 2026.

On funding, a depot can be bought outright with cash or asset finance, which suits an owner-occupier and keeps all the allowances and savings in house, or taken on a power purchase agreement where a tenant prefers zero capex and an off-balance-sheet arrangement, paying per kWh below grid retail. For a parcel operator standardising across many leased depots, a PPA framework can be the simpler way to roll out at scale without committing capital site by site. Our cost guide sets out the depot economics including the EV charging element and compares the routes.

Funding routes in detail

Most depot installs are fully expensed in year one under the Annual Investment Allowance, which keeps the net cost of a smaller system low and makes the payback genuinely quick once the tax shield is counted. Pure logistics depots generally fall outside the Industrial Energy Transformation Fund, but if a depot sits within a Freeport or Investment Zone, such as Felixstowe and Harwich, Liverpool, Teesside, Solent, Thames, Humber or East Midlands, it may qualify for 100% Enhanced Capital Allowances on new plant and machinery, so we check eligibility for every applicable site.

Because last-mile depots are very often leased urban units, the Green Lease route is the practical unlock and frequently the deciding factor in whether solar happens at all. We work to the Building Better Partnership Green Lease Toolkit and provide the aligned addendum so a tenant operator can install solar with landlord consent and clear end-of-lease treatment, which matters when the same operator is rolling out across many leased sites and needs a repeatable template. Institutional landlords typically consent in four to eight weeks, owner-occupied or family-owned property faster, and the addendum covers the end-of-lease options of removal, transfer at agreed value, or PPA continuation. The detail is on our funding page.

Compliance and sector considerations

Urban planning is the main difference for last-mile. A depot in a town or city is more planning-involved than a rural distribution site, so we factor local authority requirements into the timeline early, though most rooftop PV still proceeds under permitted development through Class A Part 14 of the GPDO 2015. The second sector-specific point is designing the EV charging infrastructure alongside the PV, so that the array, the chargers and the building load are balanced through the distribution board and the DNO connection, rather than bolting chargers onto a connection that cannot carry them.

The usual logistics standards apply: LPC sprinkler clearances where sprinklers are fitted, at 1m to the deflector and 0.6m at high-bay, insurer pre-design review and sign-off, and wind loading to BS EN 1991-1-4 for the building's exposure. A G99 grid application applies above 17 kW per phase, which on a smaller depot with added EV load needs careful capacity assessment with the DNO, because the combined demand of charging and any export can push a modest urban connection to its limit. Getting that connection question answered early is the single most important step in delivering a depot on time, because a connection upgrade is often the longest item in the programme and the one most likely to slip if left late. We confirm the available capacity with the DNO before committing to the charger count, so the design we propose is one the grid can actually carry.

How we approach this kind of project

We start with your half-hourly meter data and the van charging schedule together, because on a depot the value is in matching solar generation to the daytime charging window. We design the PV and the EV charge points as one system, submit the G99 application early so the connection and any capacity upgrade for the chargers progress in parallel with the roof survey, and we check the roof build-up and any urban shading before committing to a fixed-price proposal. For leased urban units we engage the landlord with the BBP addendum, which is especially useful for operators standardising across a national depot estate and needing the same documentation at every site.

The roof install happens above live operations, so vans continue to load and depart normally throughout, with only the final grid synchronisation requiring a short scheduled window, ideally outside the morning despatch. The workmanship is covered by a ten-year insurance-backed warranty, and delivery runs through MCS, NICEIC, RECC and TrustMark certification. For a parcel operator the goal is a depot that quietly fuels its own electric fleet from the roof while cutting the import bill that fleet would otherwise inflate. Done well across an estate, the same design repeats from one depot to the next, so each new site is faster and cheaper to deliver than the last and the whole network moves toward its electrification target on the same template.

An illustrative example

As an illustrative composite based on typical UK last-mile projects: a parcel operator electrifying an urban delivery depot installed around 300 kW, roughly 555 panels, across the building roof, paired with a dozen van charge points, generating in the region of 280,000 kWh a year. With the fleet charging through the day, much of the generation was consumed on site at full displacement value, the qualifying cost was written off under the Annual Investment Allowance, and the payback came in near 5.5 years. The figures are illustrative and depend on your roof, fleet size, charging pattern and tariff.

If your network also includes larger sortation hubs or refrigerated depots, see distribution centre solar and cold storage warehouse solar. When you are ready, read the cost guide and funding routes, then request a free feasibility or browse the industrial unit solar FAQs.