Commercial solar leasing vs outright purchase UK

Outright purchase means your business owns the solar plant and keeps the electricity it produces. An operating lease or an on-site power purchase agreement means a funder owns the plant and you pay to use it, as rent or as a price per kilowatt-hour. The choice between commercial solar leasing and outright purchase on a UK site is settled by how long you will stay, how much power you use while the site is open, and whether the roof and the local network can support the array. Hire purchase is closer to buying. An off-site corporate PPA does not put panels on your building.

Cash at the start, who repairs and insures the array, and what happens if you sell or leave the building all follow from that ownership line. So does the comparison with the grid import you would otherwise pay. Export income, tax treatment and any claim that the arrangement is off the balance sheet are secondary. Several of them have to be read from the contract and checked against current rules, not assumed from the product name.

Neither route is a default for every UK commercial roof. A short occupational lease, a covering that needs replacement, very low use during generating hours, or a connection the network operator will not offer on acceptable terms can rule out both. Installed cost, lease rentals, on-site PPA unit rates and payback are not stable national figures. This guide explains how to compare offers, not what yours will cost. On a live project the sensible order is site control, load shape and connection, then the finance label. A funder term sheet and a purchase quote can both be rewritten once a structural report or an export limit arrives. Comparing two unit rates before those facts exist is how a business picks a contract it later cannot build.

Who owns the panels under each contract

Under outright purchase the occupier owns the panels, inverters and mounting from commissioning, whether the money came from cash or from the business's own loan. Under an operating lease the funder owns the plant and the occupier pays a rental to use it. Under an on-site PPA the funder owns the plant and charges for electricity generated, usually from a starting price with an escalation clause written into the offer.

Hire purchase and finance leases sit nearer to purchase than to a pure rental. Title may pass at the end, or on a final payment, but the documents vary. Read the title clause rather than assuming the marketing name tells you who owns the asset. The answer matters if you sell the building in year three. A lender's security over your business is not the same thing as a solar funder owning the roof plant.

An off-site corporate PPA, where a supplier sleeves power from a remote solar farm, is a different product. It does not replace a roof survey, landlord consent or a distribution network connection for generation on your own site. Keep a rooftop lease, an on-site PPA and an off-site PPA in separate columns. Mixing them makes both the saving and the risk look cleaner than they are. In practice the ownership line decides the rest of the file. The owner usually wants structural sign-off, a fixing method that the roof warranty can survive, insurance, and a right to leave the plant in place for the asset life. If you are a tenant, you may be the energy user without being the person who can grant that right. That mismatch stops more projects than the choice of inverter.

How the charge compares with grid electricity

The fair test is not whether a PPA looks cheaper than today's import tariff on a single unit. It is whether the rent or the unit rate, on the same generation assumption and the same term, beats owning the system yourself. It also has to beat carrying on importing from the grid. A lease or an on-site PPA is not free solar. The funder's cost of capital, operations and risk sit inside the price you pay.

Commercial solar vs grid electricity for UK businesses is, in most occupied buildings, a question of how many imported units you can avoid while the site is open. A kilowatt-hour used on site displaces an imported kilowatt-hour. A kilowatt-hour exported is a different benefit, and only if you are allowed to export it and a supplier pays for it. Capacity in kilowatts is not the same thing as energy in kilowatt-hours. A larger array is not automatically more valuable if the building cannot use the extra energy and the network will not take it.

A model built only on annual consumption, without the half-hourly shape of the site, will mis-state both a purchase case and a PPA comparison. Check what the PPA actually bills. Some charge for generation and some charge for energy delivered to the building. If you pay for units you cannot use and cannot export, that unit rate is not comparable with an import tariff. An export limit, or a building that is shut, can put you in that position. Indexation and any minimum payment move the later years. A price that looks keen against today's supply contract can drift if it escalates and your import contract does not, or the other way around. Compare both routes over the same term, with inverter replacement visible on the purchase side and escalation visible on the funded side. Do not annualise year one and multiply.

When outright purchase is the stronger fit

Outright purchase tends to fit an owner-occupier that expects to stay, can fund the system, and uses a large share of generation during operating hours. That business is choosing to keep the energy benefit and to hold maintenance, performance and replacement risk itself. What changes the purchase quote is roof condition, connection works, access for maintenance and how much of the yield the building can use. It is not a catalogue price per panel.

It is a weaker fit if cash is needed in the core business, if the site may be vacated soon, or if the roof cannot carry a long installation without major works. Buying does not remove output risk. Yield still moves with weather, shading, downtime and changes in how the building is used. A quiet site after a change of shift pattern produces the same kilowatt-hours and a smaller saving.

A bank loan arranged by the business is still a purchase for this comparison. You own the plant and the energy benefit, and you still need a maintenance plan. What differs from a solar funder's contract is where title, early repayment and security sit. Put those clauses in the comparison before you drop both offers into one column labelled finance.

When a lease or on-site PPA fits better

An operating lease or an on-site PPA tends to fit a business that will not deploy capital and wants operations and performance remedies written into the contract. You still have to satisfy a funder's checks on roof, credit and tenure. It works cleanly when the party that uses the power is the party that pays, or when landlord and tenant already have a clear recharge. Your credit changes whether a funder will offer, and on what terms. It does not change the physics of the roof.

A low unit rate on a roof nobody has surveyed is not an offer. Funders decline sites. A refusal is information about roof life, credit, term or connection, not a reason to force a purchase the business did not want to make. If the funder will not take the risk, ask what they saw before you decide to take that risk yourself.

Neither route is a sensible default where the occupational lease is short, the roof is due for replacement, the covering is structurally inadequate or hazardous, use during generating hours is very low, or the network operator will not connect on acceptable terms. Selling the building without a right to assign the solar contract is a common reason to wait, whether you own the plant or a funder does. Listed buildings and conservation constraints belong in the same group until consents are clear.

Roof life, consent and how long you will stay

Site control often matters more than the finance label. The roof or the ground has to carry the array for the asset life or the contract life. Remaining roof life, fragile or asbestos coverings, shading and safe access for maintenance all constrain the design before anyone should talk about savings. If a competent survey says the covering should be replaced first, both purchase and lease should wait.

Where the occupier is a tenant, landlord consent, the unexpired lease and dilapidations need to match the solar term. A long solar contract on a short occupational lease is a mismatch unless assignment, reinstatement and what happens at a break are already agreed. Landlords also worry about penetrations, the warranty on the covering, and who makes good at the end. Multi-let offices and retail units add a further question: who is the offtaker, and does that party pay the bill the solar is meant to reduce.

On a flat membrane roof, ballast can avoid penetrations, but it adds weight the deck must accept. A structural assessment and a wind design are normal requirements for a funder or an insurer, not optional extras. Fragile roofs and asbestos are common on older UK commercial stock and can stop a scheme that looks simple from the car park. Installing over a roof you expect to strip is how lift-and-reinstall costs appear later, often with no named party to pay them. Planning permission, listed-building consent and conservation-area controls should be checked for the building in front of you. Non-domestic permitted development is not a blanket answer, and a quotation that assumes consent is not consent. If the building is listed or in a sensitive setting, treat both purchase and a funded roof as paused until the planning position is clear.

What a commercial solar G99 connection can change

Larger commercial arrays are often beyond the small-scale notification route and need a distribution network operator application, widely referred to as G99 rather than G98. Exact thresholds, timescales and any reinforcement charges are regional. Take them from the operator for that postcode and from the current engineering recommendations, not from a quotation template or from another site's programme.

Export limits, queue time and connection works can shrink the buildable system or push back the date any saving starts. That hits a purchase case and a PPA case in the same way. No generation means no avoided import. Protection settings and an export limitation scheme are often part of the connection offer. They belong in the design before the financial model is treated as final.

Ask which operator covers the site, whether the proposal is a notification or a full application, and whether export is limited below the array's peak. Also check spare capacity on the existing switchgear, space for generation metering, and whether a landlord's private network sits between you and the public network. Those points change who may apply and when a saving can start. Do not publish a go-live date that assumes a connection you have not got.

Warehouses, offices and retail roofs

There is no single commercial solar panel cost for UK warehouses, offices or shops that you can lift into a business case. Installed cost, lease rental and on-site PPA rates vary with roof, region, system size, connection works and credit. Treat a national pounds-per-kilowatt figure as unknown until a survey prices the roof you actually have. The same caution applies to simple payback.

A warehouse that runs through the day, with a large and relatively clear roof, is often the simplest load shape to set against solar. The case still fails if the covering is fragile, shading from neighbouring yards is severe, or the real demand is at night and the weekend while the array is producing into an empty building. Size against half-hourly import, not against floor area. Annual consumption alone will not show that mismatch.

Commercial rooftop solar for UK offices is more often limited by plant already on the roof, cramped access and a load that falls sharply outside office hours. Solar for UK retail parks and shops adds landlord structures, common-part supplies and trading hours that may not match irradiance. In each case the useful comparison is avoided import during occupied hours, plus any export you are actually allowed to sell. If you are also adding electrified heat or storage, put that load and that connection impact in the same model. Storage can move some solar into later hours, but it does not cancel an export limit. Do not treat stored energy as if nothing were lost in the round trip.

Who maintains the array and replaces the inverters

Under purchase, maintenance, insurance and replacement sit with the business unless an operations contract moves them. Under a lease or an on-site PPA they sit with the funder only where the wording says so. A line in a brochure that says the provider takes care of everything is not the allocation. The schedule and the default clauses are.

Module performance warranties are commonly in the region of 25 years. Inverter warranties are shorter, often around 10 to 15 years, so a purchased system should budget for inverter replacement inside the module warranty life. Those periods are typical warranty practice, not a promise that your array will perform for that long. Lease and on-site PPA terms are often somewhere between 10 and 25 years. The actual term, the indexation and any minimum payment are specific to the offer in front of you.

Annual output per kilowatt-peak is not a single UK number. Irradiance, tilt, orientation, shading and system losses change yield by postcode and by roof. Take yield from a site model, and take degradation from the module warranty, not from a generic percentage on a slide. A funder and a purchaser can use the same yield file. If they do not, you are not comparing like with like.

Also name who monitors, who cleans, who insures the array and who owns any renewable certificates. Current-transformer errors on the meters will undermine both a PPA bill and a performance claim. Metering is part of the commercial terms, not a detail for commissioning week. Inverter location, edge protection and safe access decide whether anyone can maintain the plant for the full term. Grid-tied solar does not, by itself, keep a site running in a power cut. Backup is a separate design. Do not assume it from a purchase quote or from a PPA.

Tax, the balance sheet and export income

Do not assume a lease or a PPA is off the balance sheet, and do not assume purchase unlocks a particular tax result. Companies reporting under IFRS 16 generally recognise leases on the balance sheet. A PPA is not automatically the same thing as a lease, and some contracts contain lease-like terms. Other UK reporting frameworks can differ. An auditor has to classify the document you sign, not the label on the cover.

Capital allowances on company-owned solar, VAT on a commercial supply and install, and business-rates treatment of rooftop plant should be confirmed for your entity against current rules. They are not stable facts to copy from an article, and they can change the cash comparison without changing the engineering. Ask an accountant to review the heads of terms you have been offered. A generic claim that solar is tax efficient is not a calculation.

Export income is often treated as the point of the project. For many occupied commercial buildings the larger figure is imported electricity avoided. The Feed-in Tariff is closed to new applicants and should not appear in a new-project comparison. Smart Export Guarantee eligibility, supplier rates and any clash with your existing supply contract need a current supplier or official source before export revenue goes into the model. No grant is assumed here. A scheme belongs in the case only if a live UK or devolved scheme has been verified for your site. Certifications such as MCS should not be described as always required or never required until the warranty, the contract and any live scheme have been checked.

What to settle before you rely on the saving

Choose purchase when you will stay, you can fund the plant, and you are willing to hold performance and replacement risk in exchange for the energy benefit. Choose a lease or an on-site PPA when you will not deploy that capital, the funder accepts the roof and the tenure, and the contract genuinely moves the risks you do not want. If the roof, the lease or the connection fails, choose neither yet. Payback is not a national figure. It moves with your import price, self-consumption, connection cost and any indexation. Use the same generation assumption, the same term and the same export limit on both sides. A funder price that excludes connection works is not comparable with a purchase price that includes them. A purchase saving that assumes unconstrained export is not comparable with a funded array already cut back to a network limit. Ask for the assumption sheet, not a single headline year.

Overview

Before you treat either saving as real, gather a year of half-hourly import if the supplier can provide it, the unexpired lease, and any roof survey you already hold. Ask the installer or funder for structural sign-off, the fixing method and its effect on the roof warranty, the network application status, the export limit, and named responsibility for inverter replacement, monitoring, cleaning, removal, early termination and assignment. If those items are still open, the finance comparison is early. Signing to hold a price can lock you to a design the roof or the network will not support.