Guarantees of origin · Glossary

Guarantees of origin (GOs) are electronic documents. They certify how and where electricity from renewable energy sources was generated and fed into the grid. The German Environment Agency (Umweltbundesamt) compares them to a birth certificate. A certificate contains at least the renewable energy source, such as photovoltaics, wind power, hydropower, biomass or geothermal energy, as well as the location of the installation and the period of generation. It describes an attribute of the quantity of electricity generated. It does not document the physical path of the energy to a specific consumer. Nor does it judge the ecological quality of the generation or of an entire electricity product. That is only done by green electricity labels with their own criteria.

In the EU, Article 19 of the Renewable Energy Directive governs guarantees of origin, most recently amended by Directive (EU) 2023/2413 (RED III). The standard size is one megawatt hour. Since the amendment, it may be divided into fractions, provided that each fraction is a multiple of one watt hour. For each unit of energy produced, no more than one certificate may be issued. Member States are also to make it possible, where feasible, to issue certificates in fractions and with a timestamp closer to real time. Besides electricity, the system now also explicitly covers renewable gases, including non-biological hydrogen.

Life cycle: issuance, transfer, cancellation

A guarantee of origin goes through three steps. It is issued for a measured quantity of generation, can then be transferred, including across national borders, and is finally cancelled. Only cancellation allows an electricity supplier to declare the quantity concerned as renewable to its customers. A cancelled certificate cannot be used again. In this way, the same attribute cannot be sold more than once. For green electricity supplies, the supplier must cancel a corresponding number of guarantees of origin.

The certificates can only be used for a limited time. Under the EU Directive, they may be traded up to twelve months after generation. At the latest 18 months after generation, all certificates that have not been cancelled expire. Expired certificates flow into the so-called residual mix. This is the mix that is allocated to all electricity quantities without their own guarantees of origin. Under German law and the EECS industry standard, further deadlines may apply in detail.

Book-keeping allocation instead of physical delivery

In the grid, the electricity from all power plants flows together. At the socket, it is impossible to tell whether the energy just drawn comes from a wind farm, a gas-fired power plant or a solar installation. Electricity flows result from feed-in, withdrawals and grid characteristics, not from contracts. A green electricity tariff with guarantees of origin therefore does not mean that a household receives electricity from exactly the named installations at all times. One can imagine it as a lake: someone pours a bucket of water in, and someone else scoops a bucket out. The certificate only regulates to whom the attribute of the water poured in is attributed.

This separation is central to understanding the electricity market. Physical distribution follows the technical conditions of the grid. Settlement, by contrast, takes place via contracts, balancing groups and market rules. Guarantees of origin belong to the commercial and regulatory level. Grid operators are responsible for stability, frequency maintenance and congestion management, regardless of how the certificates are distributed.

The reference quantity is an amount of energy, that is, megawatt hours. Power in megawatts is something different. An installation with a capacity of one megawatt generates one megawatt hour if it feeds in at full capacity for one hour. A classic certificate covering a month or a year says little about whether the generation matches the load profile of a consumer.

Legal framework in Germany

In Germany, the Umweltbundesamt issues guarantees of origin for electricity. The basis is Section 79 of the EEG 2023 (Renewable Energy Sources Act). The agency also transfers and cancels the certificates and, on application, recognises foreign certificates. It records issuance, recognition, transfer and cancellation in an electronic database, the guarantee of origin register (Herkunftsnachweisregister, HKNR). It is also to protect the certificates against misuse. For each megawatt hour generated and supplied to end consumers, no more than one certificate is issued. The register began operation on 1 January 2013.

Decisive in practice is the prohibition of double marketing. Guarantees of origin are only granted for electricity from renewable energy sources that is sold directly without EEG support, that is, without a market premium, feed-in tariff or tenant electricity surcharge. An example: a hydropower plant without EEG support can receive guarantees of origin. A PV installation with a feed-in tariff receives none. The EU Directive expressly leaves this choice to the Member States, so that the market value of the certificates can be taken into account in the support. For electricity with a market premium, the Umweltbundesamt has so far been able to issue regional certificates instead. They only certify regional origin.

Electricity supported under the EEG appears in electricity labelling as a separate share. According to the Umweltbundesamt, this EEG share is the same size for all customers. If a supplier additionally declares “renewable energy with guarantee of origin, not supported under the EEG”, it must present cancelled certificates in the register for this. According to the Umweltbundesamt, about a tenth of the electricity, namely 11.4 percent, comes from renewable energy with guarantees of origin that was not supported under the EEG. A large part of these certificates is imported, for example from Scandinavian or Alpine hydropower.

Distinction from green electricity and additionality

Guarantees of origin are the standard instrument for declaring renewable quantities in electricity labelling. They are not to be equated with green electricity in the demanding sense. Whether a tariff incentivises new installations, finances a particular installation over the long term or matches consumption in time cannot be read from the certificate alone. This is where the concept of additionality comes in. A certificate from a run-of-river hydropower plant that has been fully depreciated for decades correctly documents one renewable megawatt hour. However, its effect on new investment may be small if certificate prices are low.

A long-term supply contract with a new installation, a so-called power purchase agreement, can work differently. It secures revenues and eases financing. RED III requires that the associated guarantees of origin can be transferred to the buyer of such a contract. Here too, it remains to be verified whether the certificates are actually transferred and cancelled and not additionally marketed elsewhere.

Market prices and corporate accounts

Many companies account for their electricity consumption on a market basis for climate reporting and use cancelled guarantees of origin for this. This creates demand and prices. If many certificates from existing installations are on offer and demand remains limited, prices are low. They rise when buyers specifically demand certain technologies, countries of origin, new installations or time-matched generation. The effect of the instrument therefore depends heavily on scarcity and quality requirements.

Temporal matching and system impact

So far, accounting is predominantly based on annual quantities. A data centre with high night-time consumption can, for example, cancel certificates from solar power, even though this arises mainly at midday. For the accounts, this is permissible, but technically incomplete. For flexibility, storage needs and residual load, this difference plays a major role. Because the EU allows smaller certificates and timestamps close to real time, hourly or quarter-hourly certificates become possible. They do not change electricity flows. But they show whether generation and consumption actually fall into the same time windows. In this way, they can create incentives for storage, controllable loads and complementary generation profiles.

A guarantee of origin does not automatically mean that emissions were avoided. The climate impact of a procurement model depends on which generation is displaced, which installations are additionally built and how the overall system is operated. The certificate documents the origin of a quantity of electricity, not its effect on the power plant fleet.

What the concept achieves and what it does not

Guarantees of origin clarify who may claim the renewable attribute of a megawatt hour. They prevent double counting within the register system. They provide neither capacity nor grid capacity or controllability and do not replace an investment decision. The concept is used precisely when certificate, supply, support and system impact are kept apart. It creates order in electricity labelling, but does not replace a technical or economic analysis of the electricity system.

Sources

Richtlinie (EU) 2023/2413 (RED III) — Europäische Union, EUR-Lex; 2023-10-18. Art. 1 Nr. 9 (Änderung von Art. 19 Abs. 2 RL 2018/2001); Erwägungsgründe
Strom-Herkunfts- und Regionalnachweise: Fragen und Antworten — Umweltbundesamt; 2026-11-09 (zuletzt aktualisiert). Abschnitt Herkunftsnachweise für Strom
EEG 2023 § 79 Herkunftsnachweise — NWB Gesetze (Wiedergabe des Gesetzestexts); unbekannt. § 79 Abs. 1, 3, 4 EEG 2023
Welche Bedingungen müssen für den Erhalt von Herkunftsnachweisen erfüllt sein? — Umweltbundesamt; unbekannt (Rechtsstand EEG 2012). FAQ-Antwort
RED III – main changes for GOs — Association of Issuing Bodies (AIB); 2023 (genaues Datum unbekannt). Abschnitt Article 19

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Edited by eCMS on 12.11.2026 05:05