25-Year Warranty – But What Does That Really Mean?
Most solar modules come with a so-called performance warranty of 25 years. That sounds impressive, but what's behind it? The manufacturer guarantees that the module will still deliver at least 80–85% of its rated power after 25 years. So, the system doesn't just stop working – it slowly becomes slightly less efficient.
In practice, many systems operate smoothly for over 30 years. The critical factor is not just the module, but the overall system – and that's often where the weak points lie.
What Really Ages: The Underestimated Components
Inverters: Power electronics have a shorter lifespan than modules – typically 10–15 years. An inverter replacement during the system's operation is normal and should be budgeted for.
DC Cables: PV cables are designed for decades of outdoor use. Their weak point is not the cable itself, but the points where it is exposed to mechanical stress – especially at the roof penetration and over sharp roof edges. Those who cut corners during installation here will pay for repairs later.
Connectors (MC4): Oxidation and poor contacts are a common source of faults. High-quality, properly crimped connectors last for decades. Cheap or incorrectly installed ones do not.
Roof Penetration: Cheap seals embrittle after a few years. A good cable gland with an abrasion-resistant cable sleeve not only protects against moisture ingress but also against mechanical wear of the cable itself.
Maintenance: What You Can Do Yourself
Annual Visual Inspection (Autumn):
- Are the modules clean? Soiling from moss, leaves, or bird droppings can noticeably reduce yields.
- Are all cable connections still tight and visibly undamaged?
- Is the roof penetration still sealed? Has no water entered?
- Does the monitoring app show normal yields compared to the previous year?
Every 5 Years (by specialist company):
- Insulation measurement of DC lines
- Thermographic imaging of the modules (shows hot spots and defective cells)
- Checking all connectors
When Is a System Renovation Worthwhile?
If the inverter fails after 12–15 years, a replacement is almost always worthwhile – new devices are more efficient and often cheaper than repairs. If the modules are still functioning well after 20+ years, expanding the system may make more sense than a complete replacement.
A good PV system that was properly installed from the outset – with correct cable routing, secure penetration, and clean connection – causes minimal maintenance over 25 years.
Conclusion
PV systems last a long time – if they were built well. The critical weak points are not the modules, but inverters, cable connections, and roof penetrations. Those who pay attention to quality there will save themselves expensive surprises in 15 years.
In the NEXCAPE® shop, you'll find cable glands designed precisely for this long-term stress.
