Non-conformity in solar panel installations: leakage, the right to cure and conversion
Innodura fits 26 solar panels with the wrong fixing — leakage follows
In August 2018 the buyers enter into an agreement with Innodura B.V. for the supply and installation of 26 solar panels on their home, for an amount of €9,545.95 excluding VAT. Innodura subcontracts the installation to subcontractor Solarmere B.V. The panels are fitted in September 2018. During the course of 2019 the buyers discover a leak in the attic.
They report the leak to Innodura. An engineer visits but cannot establish the cause. Several attempts to cure then follow in the autumn of 2019: holes are sealed with sealant, damage is finished off. The leak persists. In December 2019 an independent expert firm (Top Expertise) issues its report: the mounting rails have been screwed to the PVC roof and sealed with sealant, whereas a PVC roof requires specific roof anchors or PVC profiles. The screws with sealant can cause cracks. The expert estimates the repair costs at €5,500.
Declaration of conversion holds up after a conditional repair offer
On 8 January 2020 the buyers' representative gives Innodura notice of default: cure within 21 days, failing which they will have the work carried out by a third party at Innodura's expense. Innodura does not respond within the period. On 29 January 2020 the buyers convert their claim to performance into a claim for replacement damages — the so-called declaration of conversion under Section 6:87 DCC. As a matter of goodwill, Innodura is given a further seven days to confirm after all that it will carry out the repair itself.
Innodura then has a counter-expertise carried out (April 2020), but it does not refute the conclusions of Top Expertise. On 18 May 2020 the buyers give Innodura a final chance: to confirm within seven days that it will provide proper repair. Innodura responds on 19 May 2020: subcontractor Solarmere is willing to attend on 12 June — but only if the leak was caused by the panels. In a letter of 27 May 2020 Innodura additionally suggests that the layout plan modified by the buyers could be the cause.
The Court of Appeal holds that this was not an unconditional undertaking. Innodura made the repair dependent on further investigation into the cause, implicitly disputed the expert report, and suggested that the repair could be completed in a single day — whereas scaffolding was needed to remove and refit the panels. The declaration of conversion of 29 January 2020 had thereby become irrevocable: the buyers retained their right to replacement damages and were entitled to engage a third party for the repair.
The buyers requested two quotations: Solention (€8,791.38 including VAT) and I.B.W. (€8,762.20 excluding VAT). They chose the lowest quotation, which the Court of Appeal regarded as being in line with the market. The Court of Appeal awards the actual invoice amount of €8,791.38 — not the expert estimate of €5,500. The subdistrict court had earlier taken the estimate as its starting point, but the Court of Appeal finds that Innodura had not disputed, with reasons, the actual repair costs (scaffolding, removal of the panels, fitting of roof anchors, reinstallation). In the indemnity proceedings Solarmere is held liable as subcontractor: it chose the wrong fixing materials, knew that it concerned a PVC roof, and had for months failed to respond to Innodura's requests.
What does this mean for buyers and installers of solar panels?
The solar panel market generates a stream of disputes. The case law shows a pattern in which three questions are central: is there non-conformity, has the buyer given the installer sufficient opportunity to cure, and how are the damages assessed?
Not every imperfection amounts to non-conformity. A recent decision of the District Court of Central Netherlands (ECLI:NL:RBMNE:2026:1247) illustrates that minor damage to solar panels supplied does not automatically amount to non-conformity, particularly where the panels function properly. The threshold lies at a defect that renders the panels unfit for the use for which they are intended. Wrong fixing materials that cause a leak clear that threshold comfortably.
The opportunity to cure also works the other way. The District Court of Gelderland dismissed a claim for damages in a case in which the client had given the contractor insufficient opportunity to remedy the defects, as a result of which the contractor was released from its obligation (ECLI:NL:RBGEL:2025:304). The Innodura judgment shows when that situation is in fact reversed: several failed attempts to cure over a period of more than a year, followed by an unconditional declaration of conversion, deprive the installer of the right to cure definitively. A conditional or half-hearted offer does not restore that right.
As regards the assessment of damages, an expert estimate does not set the ceiling. Where the actual repair costs turn out higher and the buyer can produce two quotations in line with the market, those actual costs are awarded — even where they approach the contract value. Solar panels almost always involve private individuals; in cases of that kind the court scrutinises critically whether the installer actually offered proper repair. More on disputes of this kind on the consumer litigation page.
Frequently asked questions
When may a buyer invoke the conversion from repair into damages?
Under Section 6:87 DCC a creditor may convert its claim to performance into a claim for replacement damages once the debtor is in default. In consumer sales, Section 7:21 DCC provides that the buyer is entitled to repair or replacement; only after a reasonable period for repair may the buyer switch to damages. Unsuccessful attempts to repair followed by a notice of default form the usual route to that end.
Does an installer lose its right to cure if it makes a conditional offer?
Yes, in principle. Where the buyer has already issued a valid declaration of conversion, the right to cure can only be regained if the buyer expressly relinquishes that right. An offer that makes repair dependent on further investigation into the cause, or that implicitly disputes the conclusions of an expert report, is not an unconditional undertaking and cannot restore the right to cure.
Are the actual repair costs compensated, or the lower expert estimate?
The actual repair costs are the starting point, provided the buyer demonstrates that those costs are in line with the market. Two quotations from independent contractors constitute strong evidence to that end. An expert estimate is an indication of the minimum, not the maximum. Where the actual performance of the work turns out more expensive because the expert underestimated the scope of the work, those additional costs are for the installer's account.
Decision: ECLI:NL:GHDHA:2024:277, The Hague Court of Appeal 20 February 2024
Cited case law
Courts of Appeal: ECLI:NL:GHDHA:2024:277
District Courts: ECLI:NL:RBMNE:2026:1247 · ECLI:NL:RBGEL:2025:304