Solar farm acceptance in Germany: when is the plant legally accepted and what changes for the contractor?

How does acceptance (Abnahme) differ from commissioning and technical test reports?

Acceptance under sec. 640 (1) of the German Civil Code (Bürgerliches Gesetzbuch, BGB) is the client’s approval of the work as essentially in line with the contract. Commissioning, measurements and test reports record the technical condition of the plant but do not express that approval. A solar farm can therefore generate electricity and still be legally unaccepted.

Acceptance belongs to the contract for work (Werkvertrag). In its judgment of 2 June 2016 – VII ZR 348/13 (para. 11), the Federal Court of Justice (Bundesgerichtshof, BGH) treated the construction of a rooftop PV system as a contract for work, not a sale with installation, because the contractor owed a functioning plant and extensive installation work. A mere supply of components falls under sales law, which has no acceptance.

No signature is needed. In its judgment of 25 February 2010 – VII ZR 64/09 (paras. 21–22), the BGH held that acceptance may be implied where the client’s conduct clearly shows approval, as a rule after a reasonable inspection period. Whether commercial operation is such conduct depends on the facts.

Where formal acceptance was agreed, the BGH (judgment of 25 February 2016 – VII ZR 49/15, paras. 38–40) upheld the finding that mere use was not acceptance, as no waiver of the formal procedure had been shown. Any such waiver should therefore be recorded expressly and in writing.

EPC contracts split completion into stages: mechanical completion, commissioning, performance tests, provisional and final acceptance certificates. Which stage is acceptance under sec. 640 BGB is a question of contractual interpretation (secs. 133, 157 BGB). Commissioning under sec. 3 no. 30 of the Renewable Energy Sources Act (EEG 2023), meaning first operation after technical operational readiness, is a separate concept that matters under the EEG but does not replace acceptance.

What are the legal effects of accepting a solar farm?

On acceptance the price falls due, the risk passes to the client, the burden of proving defects shifts and limitation for defect claims begins. The BGH listed these effects in its judgment of 19 January 2017 – VII ZR 301/13 (para. 36), describing acceptance as the dividing line between performance and defect liability. The acceptance date of every section should therefore be beyond doubt.

The price falls due under sec. 641 (1) sentence 1 of the German Civil Code (BGB). Under a construction contract (Bauvertrag), sec. 650g (4) BGB also requires a verifiable final invoice, and the client has 30 days to object to its verifiability with reasons. See our article on the final invoice (Schlussrechnung).

Until acceptance the contractor bears the risk of accidental loss (sec. 644 (1) sentence 1 BGB). Example: cables are stolen from the site before acceptance, and the contractor must lay them again without extra pay. The VOB/B grants payment for work already performed only for force majeure and other objectively unavoidable events (sec. 7 (1) VOB/B).

Before acceptance, a contractor facing a claim for performance must prove the work is free of defects (BGH, VII ZR 301/13, para. 39). After acceptance the client must prove the defect, unless it was reserved on acceptance. More in our article on construction defects and the burden of proof.

A client who accepts despite a known defect without reservation loses the rights under sec. 634 nos. 1–3 BGB (sec. 640 (3) BGB), also on implied acceptance (BGH, VII ZR 64/09, headnote 2). A contractual penalty requires a reservation on acceptance (sec. 341 (3) BGB). For defects, the client may withhold as a rule twice the cost of remedy (sec. 641 (3) BGB). Example: a EUR 15,000 repair allows EUR 30,000 to be withheld.

Can the client refuse to accept the solar farm because of minor defects?

No. Under sec. 640 (1) sentence 2 of the German Civil Code (BGB), acceptance cannot be refused for insignificant defects. The German Construction Contract Procedures, Part B (VOB/B) put it the other way round: the client may refuse acceptance until significant defects are remedied (sec. 12 (3) VOB/B).

The statute does not define a significant defect. What counts is the type of defect, its effect on operation and safety and the effort to remedy it. Example: missing labels on a few combiner boxes in a working plant suggest an insignificant defect, a failed protective shutdown a significant one. A punch list and clear test descriptions in the contract narrow the dispute.

A justified refusal keeps the price from falling due. In its judgment of 28 May 2020 – VII ZR 108/19 (para. 24), the BGH noted that the contractor can then trigger payment by remedying the significant defects. If the client is in default of taking delivery, however, the risk passes before acceptance (sec. 644 (1) sentence 2 BGB).

How does deemed acceptance work under the BGB and the VOB/B?

Deemed acceptance produces the effects of acceptance without the client’s declaration. Under the German Civil Code (BGB), the contractor sets a reasonable deadline after completion, and the work is deemed accepted unless the client refuses within it, stating at least one defect (sec. 640 (2) sentence 1 BGB). Under the VOB/B, the fiction follows from time passing after written notice of completion or after use begins (sec. 12 (5) VOB/B).

The statute does not define completion (Fertigstellung), so it is safer to set the deadline once all contractual services, including documentation, are delivered. Sec. 640 (2) BGB does not require the defect named to be significant. A refusal citing a minor defect blocks the fiction but does not show that the refusal was justified (sec. 640 (1) sentence 2 BGB).

The VOB/B has two variants. The work is deemed accepted 12 working days after written notice of completion (sec. 12 (5) no. 1 VOB/B) or, unless otherwise agreed, 6 working days after use begins (sec. 12 (5) no. 2 VOB/B). Reservations for known defects and penalties must be made by then (sec. 12 (5) no. 3 VOB/B).

Both VOB/B fictions apply only if no one has requested acceptance. Once a party has requested acceptance, especially formal acceptance (sec. 12 (4) no. 1 VOB/B), sec. 12 (5) VOB/B is out. The mechanics differ: under the BGB the contractor acts by setting a deadline, under the VOB/B the effect depends on time and on the absence of a request.

Can a solar farm be accepted in sections?

Yes, on different legal bases. Under the VOB/B the contractor may request separate acceptance of self-contained parts of the work (sec. 12 (2) VOB/B). The German Civil Code (BGB) grants no general right to this, and sec. 641 (1) sentence 2 BGB assumes the parties agreed on acceptance and prices in parts.

Under the VOB/B, limitation for a self-contained part runs from its partial acceptance (sec. 13 (4) no. 3 VOB/B), and the part can be finally measured and paid regardless of the rest (sec. 16 (4) VOB/B). Under the BGB, the price for a part agreed to be accepted separately falls due on its acceptance (sec. 641 (1) sentence 2 BGB).

Whether a section is self-contained is decided case by case. Example: a field with its own transformer station that can feed in independently qualifies more easily than the mounting structure alone. Listing acceptance sections in the contract is the safer route.

Partial acceptance differs from a joint record of the condition of parts that will be covered up (sec. 4 (10) VOB/B). On a solar farm this concerns cable trenches before backfilling and the earthing system. The record secures evidence but has no acceptance effects.

What can the contractor do if the client refuses to accept the solar farm?

First assess whether the defects are significant. For insignificant defects the contractor sets a deadline for acceptance (sec. 640 (2) of the German Civil Code, BGB) and, under a construction contract, requests a joint condition survey (sec. 650g (1) BGB). For significant defects the route to payment is, as a rule, to remedy them.

A joint condition survey (Zustandsfeststellung) is available where the client refuses acceptance stating defects. The record should be dated and signed by both parties (sec. 650g (1) BGB). If the client misses an agreed date or one set by the contractor within a reasonable period, the contractor may carry out the survey alone, sign and date the record and give the client a copy (sec. 650g (2) BGB).

The record creates a presumption. If the work has been handed over and an obvious defect is not recorded, it is presumed to have arisen later and to be the client’s responsibility, unless by its nature the client cannot have caused it (sec. 650g (3) BGB). Example: unrecorded cracked module glass counts against the client, an inverter manufacturing defect does not.

Sec. 650g BGB applies only to construction contracts (sec. 650a (1) sentence 2 BGB), which depends on whether the farm is a structure (Bauwerk), so agreeing on a survey in the contract is prudent. The price may also fall due without acceptance where the client only claims a reduction or damages, or seriously and finally refuses acceptance (BGH, VII ZR 108/19, para. 19). More in our article on acceptance of construction works.

How long is the contractor liable for defects in a solar farm?

Under the German Civil Code (BGB), two or five years from acceptance, depending on whether a structure is involved (sec. 634a (1) nos. 1 and 2, (2) BGB). Under the VOB/B, unless agreed otherwise, four years for structures and two years for other works (sec. 13 (4) no. 1 VOB/B). A period stated expressly in the EPC contract removes most uncertainty.

In its judgment of 2 June 2016 – VII ZR 348/13, the BGH applied five years to a PV system retrofitted on a tennis hall roof, because it was permanently installed, the work amounted to a fundamental renovation and the hall gained the function of carrying the plant. The court added that a PV system may itself be a structure:

„Nach der Rechtsprechung des erkennenden Senats können technische Anlagen selbst als Bauwerk angesehen werden. Das setzt voraus, dass die technische Anlage mit dem Erdboden unmittelbar oder mittelbar über ein Gebäude fest verbunden ist, ohne dass es sich um wesentliche Bestandteile (§§ 93, 94 BGB) handeln muss.”

“According to the case law of this Senate, technical installations may themselves be regarded as a structure. This requires the installation to be firmly connected to the ground, directly or indirectly via a building, although it need not be an essential component (secs. 93, 94 BGB).”

BGH, judgment of 2 June 2016 – VII ZR 348/13, para. 29 – our translation

In the same paragraph, a connection by weight alone suffices if separation takes considerable effort, provided permanent use is intended. In its judgment of 7 December 2017 – VII ZR 101/14 (headnote 2), the BGH asked whether the contract aims at a larger stationary installation with the risks typical of structures. These criteria suggest that a farm on driven piles may be a structure, but each case turns on its facts.

The judgment of 9 October 2013 – VIII ZR 318/12 (two years under sec. 438 (1) no. 3 BGB) concerned components bought and mounted by the buyer on a barn, and the VII Senate rejected its view that such a plant lacks a ground connection (VII ZR 348/13, para. 30).

The judgment of 22 October 2021 – V ZR 69/20, finding that a racked ground-mounted farm is not a building under sec. 94 BGB, concerns property law, and the BGH stressed (para. 14) that limitation law uses the concept of a structure for other purposes.

The VOB/B cuts the period to two years for electrical and electronic parts whose maintenance affects safety and functionality, unless otherwise agreed, where the client has chosen not to entrust the contractor with maintenance for the limitation period (sec. 13 (4) no. 2 VOB/B). On a solar farm this may cover inverters and transformer stations, so read the rule together with the O&M contract for the solar farm.

Frequently asked questions

Does commissioning and grid connection mean the solar farm has been accepted?
Not automatically. Acceptance is the client’s approval of the work (sec. 640 (1) BGB). Operation may amount to implied acceptance after an inspection period (BGH VII ZR 64/09), but where formal acceptance was agreed it is usually not enough (BGH VII ZR 49/15).

How much time does the client have to accept the farm?
The BGB sets no fixed period, so the contractor sets a reasonable deadline after completion (sec. 640 (2) BGB). Under the VOB/B acceptance must take place within 12 working days of the request, unless another period was agreed (sec. 12 (1) VOB/B).

Can the client refuse acceptance because as-built documentation is missing?
If the contract includes documentation, its absence is a shortfall in performance. Whether it justifies refusal depends on its significance (sec. 640 (1) sentence 2 BGB, sec. 12 (3) VOB/B). Missing documents may also put the completion needed for deemed acceptance in doubt.

When does limitation start if the farm is accepted in sections?
Under the VOB/B, for a self-contained part on its partial acceptance and for the rest on acceptance of the whole (sec. 13 (4) no. 3 VOB/B). Under the BGB limitation runs from acceptance (sec. 634a (2) BGB), so the contract should state the start date for each section.

Can an installation subcontractor demand payment once the owner has accepted the farm from the EPC contractor?
Yes. The subcontractor’s price falls due at the latest to the extent the owner has accepted the EPC contractor’s work or the EPC contractor has been paid for it, or once the subcontractor has set an unsuccessful deadline for information on this (sec. 641 (2) sentence 1 BGB). If the EPC contractor gave the owner security for defects, the subcontractor must provide equivalent security (sec. 641 (2) sentence 2 BGB).

Does the client lose a contractual penalty by accepting the farm without reservation?
As a rule yes, because the penalty requires a reservation on acceptance of performance (sec. 341 (3) BGB). Under the VOB/B the reservation goes into the formal acceptance record (sec. 12 (4) no. 1 sentence 4 VOB/B), and for deemed acceptance it must be made within the periods of sec. 12 (5) no. 3 VOB/B.

BGH case law: judgments of 25 February 2010 – VII ZR 64/09, 9 October 2013 – VIII ZR 318/12, 25 February 2016 – VII ZR 49/15, 2 June 2016 – VII ZR 348/13, 19 January 2017 – VII ZR 301/13, 7 December 2017 – VII ZR 101/14, 28 May 2020 – VII ZR 108/19 and 22 October 2021 – V ZR 69/20. Provisions: secs. 133, 157, 341, 438, 634, 634a, 640, 641, 644, 650a, 650g BGB, sec. 3 no. 30 EEG 2023, secs. 4, 7, 12, 13, 16 VOB/B. Legal position: September 2026. This article is for general information and does not replace legal advice in an individual case.

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