Careful storage of important documents is crucial when it comes to buying, selling, and operating a photovoltaic system. It is also fundamental for warranties or disputes. Find out what constitutes a reliable documentation in the following article.

No matter whether you are buying an existing photovoltaic system or a turnkey plant, or whether you are taking care of the construction yourself: in all cases, many contracts must be signed and/or taken over.

These include purchase and work contracts that were signed when the system was built, or contracts with insurance companies, financing partners and other service providers. Equally important is the paperwork necessary for the operation of the PV-system.

In the following situations, a reliable documentation is especially crucial:

• When handing over a PV system to you or to a buyer. In this case the complete paperwork, including all contracts, must be handed over. An installer checks the technical reliability of the system and whether the installation has been carried out according to the regulations.
• In case of disputes with installers.
• In warranty and insurance cases.
• In legal disputes.
• When you have maintenance carried out.
• When you want to optimize contracts.

Safety thanks to standardization

The complete documentation of a photovoltaic system has been defined in the DIN EN 62446 (VDE 0126-23) standard. It is the German version of the internationally applicable IEC standard 62446:2009 “Grid-connected photovoltaic systems – Minimum requirements for system documentation, commissioning  test and inspection”.

This norm defines a standardized documentation for photovoltaic systems. It makes sure that the most important system data are available to customers, operators, inspectors, and maintenance engineers. A sensible, state-of-the art sequence has been defined for the system documentation, which aims to provide proof of a safe installation and expectation of trouble-free operation.

When handing over the system, the installer has the opportunity to document that the system is free of defects. In case of a dispute with the installer, documentation of a photovoltaic system in accordance with the standard provides a good basis for clarifying the situation.

If it escalates to a legal dispute, the standard will probably also be used to assess the situation. In case of maintenance, all relevant data of the photovoltaic system should also be available.

Key points of the documentation

The following contents of a system documentation are essential:

Address data of the photovoltaic system: In addition to the complete contact data of the system location (incl. local contact person), this includes the complete contact data of the system operator, the system installer (general contractor) and the responsible grid operator. Furthermore, the complete contact data of the company entrusted with operational management may be included.

Important economic data: This includes e.g. the feed-in commitment of the grid operator, the commissioning date of the plant, the EEG remuneration rate, and the specification of the feed-in concept (own consumption or direct feed-in).

Important technical data:

• Plans and data sheets of the photovoltaic system
• Site plan
• String layout plans
• Allocation plan
• Circuit diagram

You also need an overview plan in the form of a single-pole equivalent circuit diagram of the entire photovoltaic system. It should show all equipment and its respective dimensions. It must therefore be clearly recognizable which cable types and which cable cross-sections have been installed.

In addition, all fuses, load-break switches, etc. must be named with the corresponding technical data.

Data sheets/manuals: this includes in particular the data sheets and test certificates of the photovoltaic modules (IEC 61215 or IEC 61646), the data sheet of the inverters, the data sheet of the substructure, and the data sheet of the grid and system protection .

Statics: this includes, among other things, the system statics of the substructure, a ground expertise for ground-mounted systems and, for roof systems, the test statics in which it has been proven that the building can absorb the additional loads caused by the photovoltaic system, taking into account the wind and snow load zone at the system location.

Guarantees: these include e.g. guarantee conditions of the photovoltaic module manufacturer, conditions for the performance guarantee of the photovoltaic module manufacturer, and guarantee conditions of the inverter manufacturer.

This list does not claim to be complete but should provide a rough overview for the creation of system documentation.

Retention periods

All contracts should be kept in an orderly manner for at least as long as rights and obligations can be derived from them. The deadlines set by the tax authorities must also be considered. Legally, the storage is bound to further rules, such as unchangeability, long-term retrievability, and reproducibility.

Due to the many kinds of relevant documents, it is not possible to define a general retention period. You can find basic standards for storage times in the § 257 HGB and § 147 AO. In addition, there are further special legal standards in § 15 BBodSchutzG, § 42 KrW/AbfG, § 29 NachwV, § 14 BImSchV, § 6 12.BImSchV.

The resulting retention periods are at least six years, but in some cases documents must be retained for ten years or longer.

This article is a free translation from the article created with the kind support of Rechtsanwalt Benjamin Bernhard, ZMUDAbernhard Rechtsanwälte.

To read the original version (in German): Wichtige Dokumente und ihre Aufbewahrungsfristen.