The answer
Should export rate drive the whole design?
An export tariff pays for eligible electricity your solar panels send to the grid. There is no single UK-wide rate: compare a supplier's current offer with the value of using that electricity yourself, and check the meter and paperwork before including export income in a payback estimate.
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How does the payment work?
Under the Smart Export Guarantee, participating electricity suppliers must offer an export tariff to eligible small-scale generators. Ofgem does not set one universal price. Suppliers decide their rates and terms, so an attractive headline rate may come with conditions on metering, equipment, contract length or the import tariff you hold.
Your smart meter normally records electricity flowing out of the property separately from electricity you buy. Generation is not the same as export: if your panels make 10 units and the house uses 6 at the time, only the remaining 4 are available for export. A battery can shift that split again. Ask for a forecast that separates generated, used, stored and exported electricity rather than counting the same unit twice.
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Is using electricity yourself worth more?
Compare the export payment per unit with the import price you avoid by using that unit while it is generated. The two prices can change independently. For example, if an exported unit earns less than a unit bought from the grid costs, running a suitable daytime load may be more valuable; it is not a reason to run equipment you do not otherwise need.
A battery introduces purchase cost and conversion losses, so moving every spare unit into storage is not automatically better than exporting. Work through a typical weekday and weekend, then test a lower export rate and a changed import tariff. This shows whether the investment still makes sense if today's price spread narrows.
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What do you need before applying?
Ask the installer for the system details and certificates the chosen tariff requires. Confirm that your electricity meter can record export, whether your supplier needs a separate export account, who submits readings and when payment begins. Keep the network connection paperwork with the handover documents.
Do not design a roof array around one currently advertised export tariff. A properly sized system should still make sense for the property if a tariff changes or you switch supplier. The roof, shading and your actual daytime demand come first; export is an additional line in the calculation.
Where this guidance comes from
Check the original guidance.
These primary sources support the technical or scheme points above. Rules can change; follow the current source before making a commitment.
Apply this to your property
Size solar for the property first.
FLO can estimate generation and on-site use, then show where export assumptions enter the financial picture.