The cavity under on-roof modules is a sheltered, dry refuge for martens. Gnawed cables can cause insulation faults, fault messages and lost yield, and are also a safety issue. The best prevention is clean cable routing from installation; brush strips or grilles can be retrofitted at the edge of the module field.
Key points in brief
- The cavity under on-roof modules attracts martens as a refuge; gnawed cables are a real but not widespread danger.
- Consequences can be insulation faults, inverter fault messages and lost yield – suspected cases belong in expert hands.
- The best prevention is cable routing at installation; brush strips or grilles can be retrofitted.
- In-roof systems are barely affected because they lack the typical cavity.
Why do solar systems attract martens in the first place?
Because the cavity between the roof skin and on-roof modules offers exactly what a marten looks for: dry, dark, protected from wind and predators – and usually without anyone regularly looking. For the animal that is an attractive retreat; the modules only make the spot additionally interesting because it is hardly disturbed.
Cables come into the sights rather by chance. Martens gnaw for various reasons, among them marking their territory or wearing down their teeth. A loosely hanging line is simply easier for them to reach than a neatly laid cable in a conduit.
What consequences can marten damage to the solar system have?
Gnawed DC cables typically lead to insulation faults that the inverter reports as a fault – often combined with a noticeable loss of yield. That's annoying but solvable. It becomes more serious when the insulation on a live line outdoors is damaged: that is then not only a yield issue but a safety question.
That is exactly why a suspected case belongs in expert hands and not in DIY. Checking around on the roof or even repairing it yourself carries both electrical and practical risks that a specialist with the right equipment covers far more safely.
How do I tell whether a marten has settled in?
A few signs point fairly reliably: scratching or thumping noises on the roof, especially at dusk, are a first hint. Droppings at the edge of the module field or on the roof are another indication. And technically, marten damage often shows up as a sudden insulation fault message in the monitoring, without any earlier irregularities.
Anyone who keeps an eye on their monitoring regularly anyway usually notices such an incident quickly – a good reason to familiarise yourself with your own system monitoring.
What really helps against marten damage?
Prevention is most effective when it starts at installation: cables in conduits and fixed with clips instead of hanging loosely under the modules – this reduces the attack surface considerably. If the system is already installed, brush strips or grilles can be retrofitted at the edge of the module field, closing the cavity without impeding the modules' rear ventilation.
Household remedies such as scents, ultrasonic devices or laid-out hair are considered unreliable in practice. Martens get used to them, and the effect often wears off after a short time. We therefore lean towards the structural solution rather than recurring effort with an uncertain result.
| Measure | Effectiveness | Time |
|---|---|---|
| clean cable routing from installation | high | at planning/installation |
| retrofit a brush strip or grille | high | possible at any time afterwards |
| household remedies (scent, ultrasound etc.) | low | ongoing, with limited effect |
| keep an eye on monitoring regularly | medium, as early detection | lasting |
Classification from practice, as of: July 2026 — the rating is based on general observations from the operation of on-roof systems.
On our systems in the Zurich region the marten is not an everyday topic but does turn up occasionally – mostly on older systems with less consistent cable routing. Where we retrofit brush strips, enquiries on this topic usually disappear for good afterwards.
Frequently asked questions
How do I notice a marten under the modules?
Typical signs are scratching or thumping noises on the roof, especially at dusk, as well as droppings at the edge of the module field. Technically, damage often shows up as a sudden insulation fault message in the monitoring, without anything having been unusual before.
Do household remedies such as smells or ultrasound help?
In practice only to a limited extent and usually short-term. Martens get used to scents and noises, so the effect fades. More reliable is a structural solution such as a brush strip that permanently closes the cavity under the modules.
Does insurance cover marten damage?
That depends on the respective policy – in particular on whether the insurance explicitly includes damage to solar systems and animal bites. We recommend clarifying this in advance with your own insurer. More on this: Insuring a solar system.
Are in-roof systems also at risk?
Significantly less. In-roof systems replace the roof skin directly, so the typical cavity that attracts martens as a refuge is missing. A complete exclusion can't be guaranteed, but the risk is noticeably lower than with on-roof systems.
Free initial consultation
Would you like to prevent marten damage from the start?
When installing your solar system we make sure the cable routing is marten-proof and advise you on sensible retrofitting. Free of charge and without obligation.
Prefer to talk? +41 78 830 83 35
Photovoltaics Switzerland – installation by a specialist company →
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: EnergieSchweiz, Swissolar, manufacturer documentation.
Last updated: 9 July 2026 · Author: ecoEn editorial team
