Alectrona
Commercial guideIf your business is large enough to fall under ESOS or SECR, on-site solar is a recognised energy-efficiency measure that lowers the energy use and the Scope 2 emissions you have to disclose.
OrientationThis is a plain-English orientation to ESOS and SECR for a commercial buyer, not formal compliance or accounting advice; we confirm the energy and carbon inputs for your project, and your advisers confirm your reporting obligations.
For a large UK business, energy is not only a cost line. It is a reporting obligation. Two schemes sit behind that: the Energy Savings Opportunity Scheme (ESOS), which makes qualifying organisations audit their energy use and identify ways to cut it, and Streamlined Energy and Carbon Reporting (SECR), which makes qualifying companies disclose their energy consumption and carbon emissions in their annual accounts.
Commercial solar is relevant to both. It is an energy-efficiency measure an ESOS audit can identify, and it directly lowers the energy consumption and Scope 2 emissions that SECR asks you to report. What follows is a plain-English orientation to how the two schemes work and where a roof-mounted array fits, so the regulatory upside of a project is something you can weigh alongside the bill saving.
The two schemes do related but different jobs, and it helps to keep them apart.
ESOS asks you to find the savings; SECR asks you to publish the numbers. Solar is relevant to both, because it is a measure ESOS can identify and a change SECR will show in the reported figures the following year.
Qualifying organisations must, on a recurring phased cycle, assess their energy use and identify cost-effective ways to cut it.
Qualifying companies must publish their energy and carbon figures in the annual directors' report each financial year.
Both schemes are aimed at large undertakings, and qualification turns on tests such as employee numbers, annual turnover and balance-sheet totals, with quoted companies brought in under SECR as well. Those thresholds are set in the regulations and are revised over time, so the precise tests, and whether a particular group structure or subsidiary is caught, are best confirmed against the current rules rather than a fixed figure quoted here.
The practical point for a finance or facilities director is that if your organisation is large enough to be weighing a commercial solar array above the domestic MCS scale, there is a good chance one or both schemes already apply, or will as you grow. We do not determine your qualification, and nor should you rely on this page for it. Your compliance or accounting advisers confirm the status; what we can do is make sure a solar project is specified so the energy and carbon effect is clear and usable in your reporting.
On-site solar changes the figures in both schemes in a direct, measurable way. Every unit the array generates and you consume on site is a unit you do not import from the grid.
The honest framing is that solar lowers the energy and carbon you report and meets the schemes' intent of using energy more efficiently. The size of each effect depends on how much of the array's output your site consumes, which is why we model self-consumption against your real load before specifying anything.
Our role is the engineering. We assess the roof with our in-house drone survey, size a system to recognised component and installation standards for arrays above the domestic MCS scale, and model the generation and the self-consumption you can expect. From that we can give you the displaced grid kWh that feed an ESOS measure or an SECR disclosure.
The reporting itself stays with your own people. The ESOS lead assessor signs off the audit, and your accountants and compliance advisers prepare the SECR disclosure in the directors' report. We provide the system specification, the expected generation and the carbon methodology they need; we do not file your return or certify your compliance. That division keeps each part with the party accountable for it.
ESOS is a phased scheme rather than a single audit, and the phase you are in sets the deadline you work back from. The Energy Savings Opportunity Scheme runs in compliance phases, each opening on a fixed qualification date and closing on a compliance date by which a qualifying organisation must have completed its energy assessment and notified the Environment Agency, which administers the scheme in England and acts as the lead UK regulator alongside the devolved equivalents in Scotland, Wales and Northern Ireland. The cycle repeats, so an organisation caught in one phase plans for the next rather than treating compliance as closed.
The assessment itself has a defined shape set out in the ESOS Regulations and the Environment Agency's published guidance on gov.uk. It must cover the organisation's total energy consumption across buildings, industrial processes and transport, identify the areas of significant energy use, and surface cost-effective energy-saving opportunities. The work is signed off by an approved ESOS lead assessor and a board-level director, and recent changes to the scheme have added an action-plan element, so the obligation now leans towards acting on what the audit finds rather than filing it. Phase dates, qualification dates and the detail of the action-plan duty are set in the regulations and revised between phases, so treat this as orientation and confirm the current phase and its deadlines against the live Environment Agency guidance rather than any date fixed on this page. Where the array itself drives the energy picture the audit characterises, the modelling sits in our feasibility study guide.
SECR is a Companies Act 2006 disclosure that lives in the directors' report rather than a standalone return to a regulator. Streamlined Energy and Carbon Reporting was introduced through regulations amending the Companies Act 2006, and for a quoted company, a large unquoted company or a large limited liability partnership in scope it requires specified energy and carbon information to be disclosed within the annual report each financial year. Because it sits in statutory accounts, the figures are read by auditors, lenders and shareholders, which is what makes the underlying method matter as much as the headline.
The disclosure has a defined content set under the regulations and the government's published SECR guidance on gov.uk. In broad terms a large unquoted company reports its UK energy consumption in kWh, the associated greenhouse-gas emissions, at least one intensity ratio, a narrative on the energy-efficiency action taken in the year, and the methodology used; a quoted company reports global emissions on a wider basis. The emissions are quantified using the Greenhouse Gas (GHG) Protocol and the UK government conversion factors, which is the same framework an honest solar carbon figure is built on, set out in our social value and carbon reporting guide. The exact scope, the de minimis exemptions and which company size tests apply are set in the regulations and have been amended since introduction, so confirm the current content requirements with your accountants rather than relying on a list here. Our part is the metered generation behind the energy and Scope 2 lines, drawn from the half-hourly metering data your site already produces.
The intensity ratio is where a solar project often reads most clearly in a SECR disclosure, because it normalises the saving against a measure of business activity. SECR requires at least one intensity ratio: emissions or energy expressed per unit of an activity metric the company chooses, such as per square metre of floor area, per unit of output or per full-time employee. A ratio strips out the noise of a growing or shrinking business and shows whether the organisation is genuinely using energy more efficiently, which is precisely the question the scheme is built to surface.
On-site self-consumption acts on both halves of that fraction in your favour. Every kWh the array generates and you use behind the meter lowers the grid electricity in the numerator, so the emissions figure falls while the activity denominator holds steady, and the ratio improves. The GHG Protocol Scope 2 guidance governs how the emissions side is quantified, and the location-based and market-based distinction it draws affects how the self-consumed and exported shares are treated, so the ratio has to be stated on a consistent basis year on year. The honest framing is that solar improves a reported intensity ratio measurably, but the size of the move depends on how much of the output your site actually consumes, which is why we model self-consumption against your real load before any figure is offered. Where export complicates the boundary, we keep the carbon side and the financial side apart and route the latter to our finance guidance.
An ESOS audit is designed to surface cost-effective opportunities, and an array sized to your daytime load is exactly the kind of measure it is meant to recommend. The scheme's purpose, as the Environment Agency sets out on gov.uk, is to identify where an organisation can use energy more efficiently and to put those opportunities in front of a board that can act on them. On-site generation sized against the demand the building actually carries through the day fits that test directly, so a lead assessor can list it among the recommended measures rather than it sitting outside the audit's scope.
Being named in the audit gives a project a documented, assessor-reviewed place in the organisation's own energy strategy that a bare bill saving does not carry. With the action-plan element now part of the scheme, a recommendation also feeds the forward plan the board signs, which is useful when a capital request needs internal justification. The recommendation is the lead assessor's call, made against the evidence; our part is to supply the system specification, the modelled generation and the self-consumption analysis that let the measure be assessed properly. The same evidence base overlaps with a commercial EPC recommendation report, which we cover alongside the building-rating duty in our MEES, EPC and commercial solar guide. None of this is a substitute for your lead assessor's judgement; treat it as orientation on how a solar measure can be carried through the audit rather than a promise that it will be.
The two schemes run on different clocks, and a solar project lands in each at a different point, so the timing is worth planning rather than leaving to chance. ESOS works to a fixed compliance date at the end of each multi-year phase, with the assessment and notification due by that date. SECR works to your own financial year, with the disclosure appearing in the directors' report for the year in which the energy was used. A system commissioned partway through a year therefore shows a part-year saving in that year's SECR figures and a full year in the next, while its place in an ESOS audit depends on where commissioning falls relative to the phase deadline.
The practical sequence is that the metered generation data is the connecting thread. From commissioning, the array produces the half-hourly generation and self-consumption record that feeds both a SECR energy and Scope 2 line and, if the timing aligns, an ESOS measure or its evidence base. Because SECR is read year on year, a consistent, dated methodology matters more than a single impressive first-year number, which is the same discipline our social value and carbon reporting guide applies. Confirm your own ESOS phase deadline and your financial-year end with your advisers, since those two dates, set respectively by the regulations and by your accounts, determine when a given install first appears in each report. The wider commercial cost picture stays survey-led and specific to your roof and load, set out in our commercial solar cost guide rather than quoted here.
Our own insured pilot flies your roof and captures the real geometry and shading, so the design starts from your building instead of a satellite guess.
Booked to suit your operating hours
We model the array in bankable-grade software, size it around your daytime load, and set out generation, savings and payback across three funding routes.
Modelled, not promised
Designed and installed to BS 7671, commissioned to IEC 62446-1, connected under G99 and run under CDM 2015. Alectrona is typically the Principal Contractor.
Outside MCS, assured by the non-MCS stack
A 12-month defects period backed by an Insurance-Backed Guarantee, then ongoing operations and maintenance so the asset keeps earning for its full working life.
Kept performing, year on year
ESOS, the Energy Savings Opportunity Scheme, is an auditing scheme: qualifying organisations assess their total energy use on a phased cycle and identify cost-effective ways to cut it. SECR, Streamlined Energy and Carbon Reporting, is a disclosure scheme: qualifying companies report their energy consumption and greenhouse-gas emissions in their annual directors' report. ESOS finds the savings; SECR publishes the numbers.
It depends on tests such as employee numbers, turnover and balance-sheet totals, with quoted companies also brought into SECR. Those thresholds are set in the regulations and change over time, so we do not state fixed figures here. If you are large enough to be considering a commercial array, one or both schemes may well apply. Your compliance or accounting advisers confirm your status; this page is orientation, not a qualification determination.
Scope 2 under the GHG Protocol covers the emissions from the electricity you buy. When you generate your own power on site and import less, that figure falls. The saving is calculated as the grid electricity you displace, in kWh, multiplied by the relevant published UK government carbon conversion factor. It is a methodology applied to your real generation, not an invented absolute tonnage.
Yes. ESOS audits are meant to identify cost-effective ways to reduce energy use, and on-site generation sized to your daytime load is exactly that kind of measure. An array can be one of the opportunities an assessment surfaces and recommends. The audit itself is signed off by your ESOS lead assessor; we supply the system specification and expected generation that inform it.
No. We design and build the solar array and model the generation and self-consumption, then give you the displaced grid kWh and the carbon methodology behind them. The ESOS audit is signed off by a lead assessor, and the SECR disclosure is prepared by your accountants and compliance advisers in the directors' report. We provide the engineering inputs; the reporting stays with the parties accountable for it.
No. The metered generation and self-consumption data that feed an ESOS measure or a SECR energy and Scope 2 line fall out of the half-hourly metering and modelling we already do, so there is no separate compliance-data line. The system cost itself is survey-led and specific to your roof and load rather than a per-kWp rate, which is why we set it out in our commercial solar cost guide rather than quote a figure here.
It depends on the two clocks. For SECR, the saving appears in the directors' report for the financial year the array is generating in, part-year if commissioned partway through, full-year after. For ESOS, it depends on where commissioning falls against your phase compliance deadline. The metered generation record starts at commissioning and feeds both, but confirm your financial-year end and current ESOS phase date with your advisers.
Last updated June 2026
A guide can only take you so far. The figure you get is modelled from your own half-hourly load and a system sized from the on-site drone survey. No obligation, and systems this size sit outside the domestic MCS scheme, so the assurance is the engineering stack.