Beyond the Pence per Kilowatt-Hour: Auditing Solar Export Terms Before You Renew

On-site solar is often presented as a simple offset to grid import: generate during the day, consume what you can, export the rest and receive a payment for the difference. In practice, the export rate quoted in a 2026 business energy offer is rarely the whole price. The value of generated power depends on how export is measured, whether the meter point is registered correctly, what the supplier assumes when data is missing and which restrictions sit in the export schedule rather than the headline summary.

For organisations weighing a renewal, the export rate deserves the same scrutiny as the unit rate on the import side. A favourable figure can be neutralised by a deemed-export assumption, an unregistered export MPAN or a cap that applies long before the site's peak generation. The audit below is intended to sit alongside the commercial review, not replace it.

Why the headline rate is an incomplete signal

Most export offers are expressed in pence per kilowatt-hour, which invites a direct comparison with import rates. That comparison is misleading. Import rates price electricity delivered to the site; export rates price electricity accepted from the site under specific contractual conditions. The conditions determine whether the rate is paid at all.

The first distinction is between deemed and metered export. Where a site has no suitable export metering, a supplier may pay on a deemed basis, typically by assuming that a fixed proportion of generation is exported. The assumed proportion is a contractual convention, not a measurement. It may be set at 50 per cent, or at another figure, and it may be applied to estimated generation rather than to actual export. Metered export, by contrast, pays for what is recorded by an export meter and settled through half-hourly data.

A headline rate of 15p/kWh on metered export is not equivalent to a deemed arrangement paying a lower rate on an assumed volume. The two produce different revenues, carry different data obligations and expose the buyer to different risks. The audit should establish which basis applies before any comparison is made.

The registration chain: MPANs, metering and half-hourly data

Export payments depend on a chain that begins with the meter point and ends with the supplier's settlement data. If any link is missing, the supplier may fall back to a deemed arrangement or decline payment altogether.

The first task is to identify the export MPAN or MPANs associated with the generation asset. Confirm that each is registered to the intended supplier and that the meter point status is consistent with active export. Check the meter serial number and confirm whether the installed meter has export registers enabled. A smart meter may be capable of recording export, but capability is not the same as configuration. The supplier must be able to collect the relevant data and use it for settlement.

The second task is to test half-hourly data readiness. Export payments that rely on metered data need a reliable flow of half-hourly consumption and export readings. In 2026, the transition to market-wide half-hourly settlement raises the standard for data quality and registration. Buyers should ask the supplier to confirm, in writing, that the export MPAN is associated with the import MPAN, that half-hourly data is being received and that no estimated readings are being used as a substitute. Where data is missing, the contract may permit deemed export, and the buyer should know that before signing rather than after the first reconciliation.

The third task is to check the physical and commercial context. A roof lease, landlord arrangement or shared supply can complicate who is entitled to export payments. Export limitation devices, connection constraints and DNO conditions may also reduce the volume available for export. These are not contract terms in the narrow sense, but they determine whether the contract's export rate can be earned.

Supplier-specific restrictions that change the value

Export schedules vary considerably between suppliers. Some impose a cap on the capacity or volume eligible for payment. Others restrict payment to particular time windows, apply a floor or ceiling to the rate, or reserve the advertised rate for customers who also take import supply on specified terms. A rate that appears competitive at the top of the offer may be subject to conditions buried in the export annex.

Buyers should check whether the export rate is fixed for the contract term or variable at the supplier's discretion. They should confirm whether payment is made separately or netted against the import invoice, and whether the export arrangement terminates with the import contract or continues independently. Change-of-supplier provisions matter as well: an export MPAN that is not transferred correctly can leave a site unpaid while the import supply moves smoothly.

It is also worth checking how the supplier treats self-consumption. Export revenue is only one part of the solar business case; the avoided import cost is usually larger. A contract that pays well for export but weakens the import terms, or vice versa, should be assessed as a package. The export rate is not a standalone prize.

Stress-testing the payback case

A payback model that relies on the headline export rate is fragile. A more defensible model uses conservative generation assumptions, a realistic self-consumption ratio and at least two export scenarios: one metered and one deemed. It should also include a scenario in which registration or data issues delay payment for part of the year.

Consider a simplified example. A site generates 45,000 kWh in a year and self-consumes 60 per cent, leaving 18,000 kWh for export. At a metered export rate of 15p/kWh, the export revenue would be £2,700. If the supplier instead deems 50 per cent of total generation to be exported and pays 5p/kWh on that deemed volume, the calculation changes to 22,500 kWh at 5p/kWh, or £1,125. The difference is not a rounding error. It is the difference between a payback case that holds and one that depends on assumptions the buyer has not tested.

Add a capacity cap, a rate reduction of 20 per cent or a three-month delay in data registration, and the sensitivity becomes clearer still. The purpose is not to predict the future with precision, but to identify whether the project's return depends on export terms that are conditional, variable or unverified.

A pre-renewal audit sequence

A practical sequence is to gather the current export statement and contract schedule, map every MPAN and meter point, confirm the supplier's data receipt in writing, read the export annex line by line and then rebuild the payback model using the terms actually offered. Where the supplier cannot confirm metered export readiness, the buyer should price the deemed alternative and decide whether the project still clears its hurdle rate.

Negotiation should focus on the conditions that erode value: the deemed percentage, the export cap, the rate variation clause and the registration obligations. A supplier that will not move on the headline rate may still improve the terms that determine whether the rate is paid.

The export rate is not the price. It is one input into a settlement arrangement, and the arrangement is what the business is signing. Before renewal, the audit should establish not only what the supplier quotes, but what the supplier will measure, register and pay.