With solar modules, there are two guarantees that must not be confused: the product guarantee (the module is free from material and manufacturing defects) and the performance guarantee (the module still delivers a guaranteed percentage of its initial power after X years). In the upper segment, up to 30 years for both have become common in 2026. The decisive factor is not the highest number, however, but the small print – and whether the manufacturer even still exists in the event of a warranty claim. (As of: July 2026)
Key points in brief
- Product guarantee and performance guarantee are two different things – both numbers count.
- In the top segment, up to 30 years of product and performance guarantee have become standard in 2026.
- The performance guarantee describes the guaranteed residual performance – the actual ageing is usually lower for good modules.
- The small print is decisive: who bears the cost of transport, removal and installation in the event of a warranty claim?
- A guarantee is only worth as much as the manufacturer behind it.
Product or performance guarantee – what is the difference?
That is the most important distinction, and it is constantly confused. The product guarantee covers material and manufacturing defects: if the module is defective, it will be replaced or repaired. The performance guarantee, on the other hand, guarantees that the module will still deliver a defined proportion of its initial power after a certain time – despite the normal ageing that every module goes through over the years.
An example of the difference: A module can be technically flawless (product guarantee therefore not affected) and still age more than guaranteed – then the performance guarantee applies. The basic functioning of both is explained in the article Module guarantee: what is covered; here it is about the comparison and the pitfalls.
What guarantee periods are standard in 2026?
The market has moved upwards. While 10 to 12 years of product and 25 years of performance guarantee were the standard for a long time, good N-Type modules in the upper segment offer up to 30 years on both in 2026.
| Guarantee type | What it guarantees | Usual range in 2026 |
|---|---|---|
| Product guarantee | free from material/manufacturing defects | 15 to 30 years |
| Performance guarantee | guaranteed residual performance after term | 25 to 30 years |
| Initial degradation | Power loss in the first year | roughly 1 to 2 per cent |
| Annual degradation | linear loss in the following years | roughly 0.4 per cent or lower for N-Type |
Rough guidelines, as of: July 2026. The concrete values are in the guarantee sheet of the respective module and differ between manufacturers and series. The data sheet of the offered module is decisive.
For context: N-Type modules generally age more slowly than older PERC modules – the actual residual performance of good modules is therefore often higher than the minimum guaranteed. How slowly modern modules age is covered in the article How long do solar modules last?.
What do I need to look out for in the guarantee sheet?
This is where marketing separates from substance. The term on the cover page says little – the decisive points are in the small print:
Who bears the ancillary costs in the event of a warranty claim? Many guarantees only replace the defective module – but not transport, scaffolding, removal and reinstallation. It is exactly these ancillary costs that can be more expensive than the module itself in the event of damage. How warranty processing works in practice is shown in the article The warranty claim: this is how processing works.
Is the residual performance guaranteed linearly or in stages? A linear guarantee (a small step every year) is more transparent than a staged guarantee with large jumps.
What conditions is the guarantee linked to? Registration, professional installation, documentation – if one of these is missing, the guarantee can wobble in an emergency.
How much is a 30-year guarantee really worth?
You have to be this honest: A guarantee is a promise for the future – and a promise is only as good as the person who makes it. A 30-year assurance from a manufacturer that will no longer exist in five years is worth little. This is not grey theory: the case of the Swiss manufacturer Meyer Burger shows how quickly a once strong name can drop out as a guarantee partner. More on this in the article Swiss solar modules.
Therefore, the guarantee always includes the question of the stability of the manufacturer: size, history, presence in Europe, bankability. A solid Tier 1 manufacturer with a slightly shorter guarantee is often the safer choice than an unknown provider with the highest number on paper. Which manufacturers are considered stable in 2026 is categorised in the article The best solar modules 2026.
When making a comparison, customers almost always look at the largest guarantee number first – understandable, but dangerous. We turn the focus to two other lines: what does the small print say about ancillary costs, and how stable is the manufacturer? We have had cases where a module had a guarantee, but the provider behind it could no longer be reached – then the most beautiful certificate is of no use. Our rule of thumb for the Zurich region: better an established manufacturer with 25 robust years than 30 years from a name that no one will know tomorrow. And: The guarantee sheet belongs in the system dossier, not in the drawer – in the event of a warranty claim, it is your most important document.
Frequently asked questions
What is the difference between product and performance warranty?
The product guarantee covers material and manufacturing defects – if the module is defective, it will be replaced. The performance guarantee assures that the module will still deliver a certain proportion of its initial power after X years, despite normal ageing. Both numbers are important and should be considered separately in the comparison.
Is a 30-year guarantee better than 25?
On paper, yes – in practice, only if the manufacturer still exists in 30 years and the ancillary costs in the event of a warranty claim are covered. A robust 25-year guarantee from a stable manufacturer is worth more than a 30-year assurance from an unknown provider.
Does the guarantee also cover the replacement?
Not automatically. Many guarantees only replace the module itself, but not transport, scaffolding and installation. These ancillary costs are in the small print – check this before buying, because in the event of damage, they can exceed the module price.
What happens to the guarantee if the manufacturer becomes insolvent?
Then the guarantee is in doubt worth little – a guarantee promise requires an existing guarantee partner. That is why the stability of the manufacturer is a central, often underestimated purchasing criterion that goes beyond the mere guarantee number.
Free initial consultation
Reading the guarantee correctly – not just the big number.
We check the guarantee sheet of the offered modules for you: term, ancillary costs and manufacturer stability – so that the assurance still holds up in 20 years.
Want to calculate yourself first? Solar calculator with official roof data →
Prefer to talk? +41 78 830 83 35
Have a photovoltaic system installed →
Swissolar-certified specialist company · ESTI installation authorisation (Art. 14 NIV) · in Zurich since 2017 · over 150 systems completed · a personal answer from the specialist company, no call centre
Sources: Manufacturer guarantee conditions (product and performance guarantee), Swissolar specialist information, empirical values from guarantee processing by ecoEn GmbH (Zurich region). Guarantee standards are developing further – as of July 2026.
Last updated: 9 July 2026 · Author: ecoEn editorial team
