Retrofitting a PV System: Cable Routing Through the Roof Afterwards
More and more homeowners are expanding their existing PV systems or having a system retrofitted on a roof that previously had no cable routing. For solar installers, this means: The cable path from the module field to the interior of the building must be created afterwards — preferably without damaging the existing roof covering.
Typical Retrofit Scenarios
- Expansion of an existing system: Additional modules require new cable routes for further strings
- First installation on an existing roof: No existing cable duct or conduit
- Storage retrofit: New wiring between module field and storage in the basement
- Inverter replacement: Conversion from string to module inverters with new cable routing
The Challenge of Retrofitting
In new buildings, cable routing can be planned from the outset. With retrofits, this preparation is missing. The cables must be routed through the existing roof covering without compromising its watertightness. Conventional methods such as drilling or routing through ventilation openings are particularly problematic for existing roofs.
NEXCAPE: The Ideal Retrofit Solution
NEXCAPE roof penetrations made of TPU (Thermoplastic Polyurethane) are perfectly suited for retrofitting. The tool-free installation works as follows:
- Remove a roof tile at the desired position
- Insert the NEXCAPE penetration
- Route PV cables including MC4 connectors
- Route cables further to the inverter in the attic space
No drilling, no sealing, no tools. The original tile is kept and can be reinserted during a later dismantling. The MC4 connectors do not have to be disconnected.
Choosing the Right Variant for Retrofitting
When retrofitting, planning the number of strings is crucial:
| Variant | Application |
|---|---|
| 2 PV / 2 PV+PE | Small expansion, one additional string |
| 4 PV / 4 PV+PE | Standard retrofit, two strings |
| 6 PV / 6 PV+PE | Large expansion, three strings |
Tip: If in doubt, choose a variant with more openings than currently needed. This way, you are prepared for a later expansion. The PE variant with an earthing cable opening is particularly recommended for retrofits if the existing equipotential bonding needs to be extended.
Made in Germany — Quickly Available
All penetrations are manufactured by 3D printing in Germany, in lengths of 105, 125, and 150 mm. For installation companies, B2B quantity discounts apply from 20 pieces.
Find a retrofit solution for your PV project: View PV Roof Penetrations
