Solar panel warranty: what the 25, 30 or 40 years really cover
The 5 warranties are distinct, and confusing two of them can leave you with no recourse. Product warranty, linear performance warranty, mandatory ten-year warranty: what each one really covers, and how to enforce your rights when needed.
- →There are 5 distinct types of warranty for a solar installation. Confusing the product warranty with the performance warranty, the most common mistake, can leave you with no recourse at the wrong moment.
- →The installer's ten-year warranty is compulsory by law (Civil Code, art. 1792). Without the signed certificate before work starts, you have no recourse in the event of poor workmanship.
- →The “80% at 25 years” performance warranty does not mean 80% tomorrow: it is a gradual degradation of 0.5 to 0.7%/year. TOPCon/HJT panels do better (0.25 to 0.40%/year).
- →Hail, lightning and storms are not covered by the manufacturer's warranty: it is your multi-risk home insurance (MRH) that steps in. Check that the panels are included in your policy.
- →The warranties do not cover defects linked to a non-compliant installation (e.g. failure to follow the DTU 40.35 standards) or to poor maintenance. Keep proof of compliance and maintenance to avoid disputes.
The 5 protections that cover your installation
When an installer talks about a “25-year warranty”, they may mean four completely different things. Understanding the difference between these protections is an essential first step before any considered purchase.
The product warranty covers material defects: encapsulant delamination, internal cell cracks, junction box failure. It is the best known, and its length varies from 10 to 40 years depending on the manufacturer. The linear performance warranty guarantees that the panel will produce at least a certain percentage of its rated power at the end of the period, typically 80% at 25 years for standard panels and 87 to 92% for high-end ones. These two warranties are distinct and may run for different lengths of time.
The ten-year warranty is a legal obligation of the installer (Civil Code, art. 1792), valid for 10 years from acceptance of the work. It covers damage affecting the structural soundness of the building work: leaks caused by poor mounting, deterioration of the roof structure, waterproofing defects. The two-year warranty (Article 1792-3 of the Civil Code) covers, for 2 years, the separable components of the installation: accessible wiring (excluding cables built into walls or roofs), secondary fixings (e.g. rails, unsealed supports), junction boxes and connectors. This warranty is mandatory for the installer and complements the ten-year warranty.
Finally, the manufacturer's longevity is an often overlooked risk: a 25-year warranty on paper is worth little if the manufacturer has disappeared. Favour brands with a solid presence and a verifiable track record.
Performance warranty: what the figure really means
“80% at 25 years” is often misinterpreted. It does not mean your panel will produce 80% from the first year, but that its residual output will not fall below 80% after 25 years of use. The loss is gradual and linear: around 0.5 to 0.7%/year for a standard panel.
Conditions for benefiting from the performance warranty
- Compliant installation: the panels must be installed in line with the manufacturer's recommendations (tilt, orientation, ventilation).
- Minimum maintenance: periodic cleaning is often required, so check the manufacturer's contract.
- Proof of production: some manufacturers ask for annual production readings from a monitoring system.
- Exclusion of external faults: the warranty does not cover losses caused by unforeseen shading or faulty wiring.
| Range | Technology | Annual degradation | Output at 25 years | Output at 30 years |
|---|---|---|---|---|
| Standard | PERC | 0.5–0.7%/year | ≥ 80 % | ~76–78 % |
| Mid-range | TOPCon | 0.35–0.45%/year | ≥ 87 % | ~85 % |
| High-end | HJT | 0.25–0.35%/year | ≥ 90–92 % | ≥ 87.4% |
Worked example
- A standard (PERC) panel at 0.6%/year will lose 15% of its output after 25 years, leaving 85% residual output.
- A high-end (HJT) panel at 0.3%/year will lose only 7.5%, leaving 92.5% residual output.
Why the gap? TOPCon, HJT and IBC technologies use materials that are less sensitive to degradation: PERC (P-type silicon): 0.5 to 0.7%/year; TOPCon (N-type + passivation): 0.35 to 0.45%/year; HJT (heterojunction): 0.25 to 0.35%/year; IBC (back contacts): 0.2 to 0.3%/year. Sources: Fraunhofer ISE (2025), NREL (2024).
Comparison of manufacturer warranties in 2026
Warranties vary considerably from one brand to another and are an indicator of the manufacturer's confidence in its own technology. Here are a few examples of well-known brands:
| Manufacturer | Product warranty | Performance warranty | Technology | Longevity The assessment is based on age (over 10 years), presence in the EU (factories or offices), stock market listing (public financial statements), market share (ability to honour warranties over the long term) and reputation (independent tests by Fraunhofer ISE, NREL). The more of these criteria are met, the more closely the warranty on paper matches a solid financial reality. |
|---|---|---|---|---|
| LONGi Hi-MO 6 | 25 years | 88% at 25 years | TOPCon N-type | ★★★★★ Global leader, listed on the stock exchange, factories in the EU |
| JA Solar JAM | 12 years | 84.8% at 25 years | TOPCon N-type | ★★★★ Global top 5, offices in the EU (DE, FR) |
| REC Alpha Pure | 25 years | 92% at 25 years | HJT | ★★★★★ HQ in Norway, factories in France, 25 years' experience |
| Aiko Solar | 25 years | 90.6% at 30 years | HJT | ★★★★ Listed on the stock exchange, EU partnerships, 10 years' experience |
| Jinko Tiger Neo | 12 years | 87.4% at 30 years | TOPCon N-type | ★★★★ Global top 3, offices in the EU, listed on the stock exchange |
| SunPower Maxeon | 40 years ★ | 92% at 40 years | IBC | ★★★★★ HQ in the USA, factories in the Netherlands, 40 years' experience |
The ten-year warranty: the legal obligation you must demand
The ten-year warranty is based on Article 1792 of the Civil Code: any builder of a structure is liable for 10 years for damage that compromises the soundness of the structure or makes it unfit for its purpose. For a solar installation, this covers leaks caused by poorly made roof penetrations, waterproofing defects, or deterioration of the load-bearing structure linked to the installation.
What the ten-year warranty does not cover: electronic failures of the inverter, production performance, or damage caused by external events (hail, lightning). It is specifically focused on damage to the structure of the building work.
To check that the installer is covered, ask for the ten-year insurance certificate before signing the contract. It must be in the installer's name, currently valid, and mention electrical and roofing work. An RGE (Reconnu Garant de l'Environnement) installer is required to provide it for any project receiving State aid.
What should I do if the installer's insurer refuses to cover a claim?
The insurer must give its reasons for refusal in writing (Article L114-1 of the Insurance Code). Valid grounds include failure to comply with the DTU 40.35 standards, failure to declare the installation, or proven lack of maintenance.
If the refusal seems unjustified to you, challenge it by registered letter with acknowledgement of receipt, enclosing all the evidence (photos, expert reports, signed contract, Consuel certificate of electrical conformity). If the dispute continues, refer it to the insurance ombudsman (mediation-assurance.org), which is free and compulsory before any legal action. As a last resort, the judicial court (tribunal judiciaire) can be seized within 2 years of the final refusal.
What the warranties do not cover
Knowing the exclusions is as important as knowing the cover. Many owners discover the limits of their warranties when it is too late to negotiate them.
Maintenance and validity of the warranties
- Cleaning: a lack of cleaning can reduce production by 10 to 20%, but does not void the warranties, unless the manufacturer proves that the defect is directly linked to it.
- Annual inspection: some manufacturers (e.g. SunPower) require an annual inspection by a professional to keep the warranty in force.
- Monitoring: if your installation is fitted with a monitoring system, keep the production data, as it can serve as decisive evidence in the event of a dispute.
How to enforce a warranty: the 4 steps
The first step is the most decisive: record and document immediately. Take dated photos, note the production readings, and keep all the screens of your monitoring system. Without evidence of the failure and of when it appeared, your case will be weak.
Then contact your installer for defects covered by the ten-year or two-year warranty, and the manufacturer for defects covered by the product or performance warranty. If both remain inactive, refer the matter to the Energy Ombudsman (Médiateur de l'énergie) (mediateur-energie.fr), whose referral is free and whose opinions are followed in the vast majority of cases.
- Installation contract (signed and dated)
- Ten-year insurance certificate (in your installer's name, with the policy number)
- Datasheets for the panels, inverter(s) and any batteries
- Consuel certificate of electrical conformity (compulsory for any installation > 3 kWp)
- Invoices (panels, inverter, labour)
- Installation photos (before/after, with dates)
- Production readings (if monitoring is installed)
- Proof of maintenance (cleaning invoices, inspection reports)
- Correspondence with the installer and the manufacturer (emails, letters)
💡 Tip: keep these documents in digital (cloud) and paper form. Some manufacturers (e.g. SunPower) offer a dedicated online customer area.
Deadlines to respect
- Ten-year warranty: 10 years from acceptance of the work (Article 1792 of the Civil Code).
- Two-year warranty: 2 years from acceptance.
- Product/performance warranty: variable (10 to 40 years depending on the manufacturer).
- Referral to the ombudsman: 1 year from the installer's or manufacturer's refusal.
- Legal action: 2 years from the final refusal (two-year limitation period for commercial disputes).
Warranties and multi-risk home insurance (MRH)
The manufacturer's and ten-year warranties do not cover everything. Your multi-risk home insurance (MRH) steps in for weather risks and physical damage unrelated to a manufacturing or installation defect.
Why declare your panels to your insurer?
Solar panels are considered fixed equipment and must be declared to your insurer (Article L122-1 of the Insurance Code). If you fail to declare them, your insurer may refuse to cover the damage or cancel your policy.
| Risk | Covered by MRH? | To be checked |
|---|---|---|
| Hail, storm, lightning | ✓ Yes | Possible exclusion of the panels |
| Fire | ✓ Yes | Replacement value (new for old) |
| Theft | ⚠ Varies | “Theft of outdoor equipment” option |
| Water damage | ✓ Yes | If linked to a waterproofing defect |
| Third-party liability | ✓ Yes | Damage caused to a third party |
How to declare your panels?
Contact your insurer before the installation to update your policy. Provide the purchase invoice, the Consuel certificate (electrical conformity) and photos of the installation. Check the exclusions: some policies exclude panels not installed by an RGE professional, or limit cover to panels integrated into the building. In most cases, adding the panels does not increase the premium.
Warranties and selling the house
Transfer of the warranties
The ten-year warranty is automatically transferred to the buyer (it is attached to the building work, not to the owner). The manufacturer's warranty can generally be transferred, but check the manufacturer's conditions, as some require a declaration of transfer. The self-consumption bonus (prime à l'autoconsommation), on the other hand, is not transferable.
Documents to hand over to the buyer
When selling a property, hand over: the installation contract, the ten-year insurance certificate, the datasheets for the panels and inverter, the Consuel certificate, proof of maintenance and production readings. State in the deed of sale the installed capacity, the year of commissioning, the remaining warranties and the average annual production.
Frequently asked questions
What happens if my installer goes bankrupt?
Does the performance warranty still apply if I clean the panels myself?
What minimum warranty period should I demand on a panel in 2026?
Does the warranty cover panels damaged by hail?
Can I transfer the warranty if I sell my house?
What should I do if my panels are damaged by hail or a storm?
Do the warranties apply to self-consumption kits (balcony kits)?
What warranties apply to storage batteries?
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