The Guarantee of Origin (GO), issued in accordance with article 15 of Directive 2009/28/EC, represents a certificate with a value of 1 MWh of the electricity supplied into the grid by qualified power plants.They are issued by the national issuing bodies of the AIB.

According to the provisions of the European Community, energy producers and suppliers need to provide information to their end customers regarding the composition of the energy mix they use, stating its environmental impact. Energy suppliers can only use the Guarantee of Origin to do so, as a proof that each MWh of energy is produced from renewable sources (biomass, hydro, wind, solar).