The Smart Export Guarantee (SEG) obliges larger electricity suppliers in Great Britain to pay small-scale generators for electricity exported to the grid. Rates are set by each supplier rather than by government, which is why published tariffs vary considerably.
Export is metered by your smart meter, so you are only paid for units that actually leave the property. Electricity you use in the home or put into your car never reaches the meter — which is exactly why self-consumption usually beats export on value.
Before signing anything, check three things: the length of the agreement, whether the rate is fixed or variable, and whether the export payments are assigned to a third party as part of a finance or installation package. Assigned export is a legitimate model, but you should understand it up front.
This article is general information, not financial advice. Terms differ by supplier and by installer.