This guide explains how the SEG works for non-domestic premises, how export tariffs are set by suppliers, and how much the revenue actually moves the payback calculation.
The Smart Export Guarantee (SEG) is the UK's export payment mechanism for small-scale renewable generators. Under the scheme, electricity suppliers with at least 150,000 domestic customers must offer an export tariff; the rate is supplier-set and must always be above zero; and the installation must be certified under MCS or an equivalent scheme.
For most commercial sites, the SEG sits alongside bill savings as a secondary revenue stream, not the primary financial case. The bulk of the value comes from using the power you generate on-site rather than exporting it. That said, any surplus sent to the grid does earn a payment, and choosing the right export tariff from the right supplier can make a measurable difference over a system's lifetime.
The SEG is not a grant. It is a payment for every kilowatt-hour you export, set at whatever rate the supplier chooses above zero. Rates vary widely across suppliers, so comparing them before you sign up is worth the time.
Total installations registered to a SEG tariff, end of Year 4 vs end of Year 5
| End of Year 4 | 166,022 installations |
|---|---|
| End of Year 5 | 270,395 installations |
The jump in registered sites shows rapid uptake, businesses that have not yet registered are missing out on payments already flowing to over a quarter of a million generators.
Ofgem - Smart Export Guarantee Annual Report April 2024 to March 2025
No regulator fixes the export rate. Each participating supplier sets its own tariff, and those rates shift over time. The only floor is that the rate must stay above zero. In practice, this means a business that accepts the first tariff it is offered may earn significantly less per unit than one that shops around.
According to Ofgem's Smart Export Guarantee Annual Report covering April 2024 to March 2025 (2026), total low-carbon electricity exported under SEG in Year 5 reached 443.1 GWh, across 270,395 installations registered to a SEG tariff at end of Year 5. That growth from 166,022 installations at end of Year 4 shows how quickly the market has expanded, and with it, competition among suppliers to attract generators.
For commercial operators, the practical step is to check the current rates from several participating suppliers before registering, then review the tariff periodically. A higher rate per unit matters most when your self-consumption share is low and you are regularly exporting a large proportion of generation.
Number of SEG tariffs available to exporters, Year 4 vs Year 5
| Year 4 | 37 tariffs |
|---|---|
| Year 5 | 50 tariffs |
The near-doubling in available tariffs between years underlines why shopping around, and revisiting your tariff annually, can meaningfully improve export income.
Ofgem - Smart Export Guarantee Annual Report April 2024 to March 2025
The share of generated electricity you use on-site is the single biggest lever in the payback calculation. Every unit consumed directly replaces grid electricity you would otherwise buy, avoiding the full unit rate. Every unit exported earns only the SEG tariff, which is typically a fraction of the retail rate.
A business with high daytime electricity demand, such as a warehouse, factory or large office running five days a week, will often use 70–80% of what it generates directly. A site with low daytime occupancy, such as a storage unit or a weekend-only venue, may export the majority of its generation and earn proportionally less from the SEG.
This means SEG revenue is worth modelling carefully for your specific demand profile before treating it as a significant payback driver. The payback period for a well-matched system is typically 9 to 12 years on an ideal roof, according to the Energy Saving Trust; export income contributes to that figure, but self-consumption savings usually do more of the work.
Illustrative payback for a commercial solar installation
| 2027 | -44,000 £ |
|---|---|
| 2029 | -32,000 £ |
| 2031 | -20,000 £ |
| 2033 | -8,000 £ |
| 2034 | -2,000 £ |
| 2035 | 4,000 £ |
| 2036 | 10,000 £ |
| 2038 | 22,000 £ |
Assumed: system cost £50,000, combined annual bill savings and SEG export payments £6,000, over 12 years. Actual results depend on tariff, consumption profile and roof orientation. Illustrative example, calculated from the assumptions in the text, not figures from a source.
Illustrative example
To register for any SEG tariff, the installation must be certified under MCS (Microgeneration Certification Scheme) or an equivalent approved scheme. This applies to commercial installations in the same way it applies to domestic ones. Using a non-MCS installer means the system cannot be registered, and you forfeit all export payments for its lifetime.
For a commercial site, MCS certification also gives the installer accountability on workmanship, system design and commissioning. Panels typically carry a 20 to 25 year product warranty, while inverters typically cover 5 to 15 years, according to the Energy Saving Trust and Which?. Those warranty horizons only protect you if the installer is certified and the paperwork is in order from day one.
Ask any installer you approach to confirm their MCS number before work begins, and check it on the MCS database. The certificate you receive after installation is what you present to the supplier when registering for a SEG tariff.
Planning rules for commercial solar differ from the domestic permitted development route. Many roof-mounted arrays on industrial or commercial buildings can be installed without a full planning application, but the rules depend on building type, size, location and whether the site falls within a conservation area or involves a listed building.
The General Permitted Development Order has been amended, and the current position for commercial premises means that larger arrays, ground-mounted systems and installations on listed or sensitive buildings are likely to need permission. Our guide on planning permission for commercial solar panels covers the current rules in detail.
The SEG eligibility check does not ask about planning permission, but installing without the correct consent can create problems when it comes to insuring the system, securing finance or selling the property. Confirming the planning position before installation protects the export income you are planning around.
Adding a battery to a commercial solar system changes the SEG picture in two ways. First, a battery lets you store generation that would otherwise be exported at a low SEG rate and use it later in the day at the full retail rate. For a site with mismatched generation and demand peaks, this usually improves the overall return.
Second, some battery systems can charge from the grid at low overnight rates and discharge during peak periods, adding a separate layer of value independent of solar generation. Our guide to battery storage for commercial solar examines when that stacks up financially and when the additional capital cost is hard to justify.
For SEG purposes, a battery does not disqualify the installation, but only net metered export, meaning power that leaves the site and reaches the grid, attracts the tariff. Power cycled through the battery and used on-site does not count as an export. Make sure your metering arrangement is set up correctly so the supplier only pays for genuine exports.
SEG revenue is real, but it is one part of a wider financial case that includes bill savings, capital cost, any applicable tax treatment and the cost of financing. For a commercial installation, the system size, roof orientation, shading and daily consumption profile all shape the outcome more than the export tariff alone.
Compare export tariffs from several SEG-registered suppliers before registering, just as you would compare installer quotes. The total installed capacity of SEG-registered installations reached 1,585 MW by the end of Year 5, according to Ofgem's 2026 Annual Report, which shows that commercial and domestic operators alike are treating export income as a routine part of the business case.
For the full picture on grants, funding and cost ranges for commercial systems, the commercial solar hub pulls together the key figures and links out to the relevant scheme pages.
The trade-offs, in short.
Tell us about your site and relevant vetted, MCS-certified installers will contact you with quotes tailored to your building and consumption profile.
Answers to the most common questions.
Yes. The SEG applies to any installation certified under MCS or an equivalent scheme, including commercial ones. The business registers with a participating supplier, which then pays a supplier-set rate for every unit exported to the grid. The rate must be above zero but varies between suppliers.
Yes. You are not tied to your electricity supplier for SEG registration. Any participating supplier, meaning one with at least 150,000 domestic customers, must offer an export tariff. Checking rates from several suppliers before registering is the straightforward way to secure a better rate per unit.
This depends on the export tariff rate, the proportion of generation exported rather than used on-site, and the total system size. Because rates are supplier-set and self-consumption varies widely by business type, there is no single figure. Modelling your own demand profile against current tariff rates gives the most reliable estimate.
Without MCS certification or an approved equivalent, the installation is not eligible for any SEG tariff. You would still benefit from self-consumption savings, but you would lose all export income for the lifetime of the system. MCS certification also underpins most product and workmanship warranties.
Adding a battery does not affect eligibility, but only power that genuinely leaves the site and reaches the grid qualifies for SEG payments. Power stored in the battery and used on-site does not count as an export. Correct half-hourly metering is needed to ensure only net exports attract the tariff.
Export income shortens the payback period, but by how much depends on how much you export and what rate you receive. Self-consumption savings typically contribute more. A well-matched system on an ideal roof has a typical payback of 9 to 12 years, according to the Energy Saving Trust, with export income as a contributing factor.
