The Smart Export Guarantee, also known as SEG, is a way for solar power generators in the UK to get paid for any of there solar power that is exported to the gird. The Government has enforced electricity supply companies that have 150,000 electricity customers or more to offer the Smart Export Guarantee (SEG) to its customers. Electricity supply firms with less than 150,000 customers still have the option to offer the SEG, but are not obliged. Ofgem who govern energy in the UK have more information here.