The RES Directive ( 2009/28/EC) promotes a substantial increase in the proportion of electricity generated from renewable energy sources across the European Union by 2020. Individual Member States have all been required to take appropriate steps to encourage greater consumption of electricity from renewables, in order that the overall EU target of 20% energy by 2020 can be met. Each State has its own indicative target, depending on issues such as historical experience with renewables.

For the purposes of the RES Directive, energy from renewable sources is defined as "energy from renewable non-fossil sources, namely wind, solar, aerothermal, geothermal, hydrothermal and ocean energy, hydropower, biomass, landfill gas, sewage treatment plant gas and biogases”.

The RES Directive requires Member States to give producers the opportunity to obtain electronic guarantees of origin (GO) for electricity generated from these sources. Member States may also, if they choose, offer GOs for heating and cooling.

GOs provide proof that electricity (or heating and cooling) has been generated from renewable sources (as defined in the RES Directive), specifying the source of the electricity; the dates when it was produced; the identity, location, type and capacity of the production facility; whether the GO relates to electricity or heating or cooling; whether and to what extent the installation has benefited from support; the date when the installation became operational; the date and country of issue; and a unique identification number.

There is no fixed price for a GO, and their value depends on market demand.

The main provisions of the RES Directive concerning GOs are contained in Article 15, which requires Member States to ensure that a GO is issued on request by producers of electricity (and, at the discretion of the Member States, heating or cooling) from eligible renewable energy sources, as defined by the RES Directive. The system is purely voluntary, and individual producers can decide whether or not they wish to make such a request.

The main provisions of Article 15:
  1. Define and limit the purpose of a GO
  2. Set out the conditions under which they are issued
  3. Specify the conditions for using a GO
  4. Set out the conditions for appointing supervisory bodies for national GO systems
  5. Lay down basic ground rules for the supervisory body
  6. Specify the content of the GO
  7. Enables GOs to be used for energy source disclosure
  8. Define the impact of purchasing and selling GOs of the supplied energy mix
  9. Lay down the conditions under which a Member State may refuse a GO
  10. Provide the Commission with the power to require a member State to recognise a GO where a reported breach of such conditions has been successfully challenged
  11. Enables Member States to define how GOs are used for the disclosure purposes of the Internal Electricity Markets Directive (2009/72/EC)
  12. Enables Member States to require energy suppliers to identify energy from new plant or increased capacity that became operational after 25 June 2009.