REGOs (Renewable Energy Guarantees of Origin) and GoOs (Guarantees of Origin) are certificates issued to renewable generators per megawatt hour of renewable electricity generated. These are purchased by suppliers and demonstrate to the consumer (and Ofgem) that the equivalent of their supplied electricity in a given year came from renewable generation. Without sufficient certificates, suppliers cannot claim to be providing a renewable supply. REGOs are issued within the UK, whilst GoOs are issued to generation within the EU. Both are currently valid within the UK for reporting purposes so we may purchase a mixture of both.