Substructure
The substructure holds the solar panels in place on the roof and transfers wind and snow loads into the building. The product range consists largely of the mounting system from K2 Systems, suitable for pitched roofs, standing seam metal roofs, trapezoidal sheet metal roofs and flat roofs. The manufacturer offers a 12-year warranty on most K2 components.
Structure: Fixing, rail, clamp
Every PV substructure consists of the same components. The roof fixings provide the connection to the building. The rails, which distribute the load, rest on top of these. Module clamps hold the modules in place on the rails – as centre clamps between two modules and as end clamps at the edges. In addition, there are small parts such as hammer-head screws, nuts, rail connectors, end caps, lightning protection clamps and connectors with equipotential bonding.
Which system suits which roof
| Roof | Mounting | Rails and mounting structure |
|---|---|---|
| Pitched roof | Roof hooks for various roof coverings, including slate and metal roofs; hanger bolts and hook bolts; wood screws 8 × 100 and 8 × 200 mm | SingleRail 36 (2.40, 4.80 and 5.95 m), SolidRail Light (2.40 and 4.80 m) |
| Seamed metal roof | CF:x double standing seam clip, without piercing the sheet metal | SingleRail 36 |
| Trapezoidal sheet metal and corrugated sheets | Thread-forming metal screws; adapter plate for M12 hanger bolts | MiniRail, BasicRail 22 with BasicLock and BasicClip |
| Flat roof | Ballast instead of roof penetration | East-west mounting D-Dome 6.10 with the ballast support Speed Porter (according to the manufacturer, up to approximately 40 kg of ballast per support) |
For flat roofs, there are ready-assembled D-Dome 6.10 mounting kits for 2, 4, 6, 8, 10 or 12 modules. They contain base profiles, mounting brackets, clamps and ballast supports; the ballast blocks are not included. According to the manufacturer, the Base Set is designed for module widths from 960 to 1,170 mm.
In addition to K2 Systems, the range includes module clamps from Solitek and a bracket for balcony railings from Hantech, which can be used to attach modules to balcony railings. For equipotential bonding between the module frame and the rack, there are lightning protection clamps, connectors with equipotential bonding and the TerraGrif clamps for the Dome system.
What needs to be clarified before ordering
Three factors determine the parts list: the roof covering, as this dictates the fixing method; the frame height of the modules, as this determines the clamps (the range includes clamping ranges such as 25 to 40, 30 to 42 or 30 to 50 mm); and the number and orientation of the modules, as portrait and landscape installations require different lengths of rail. The components of a system are designed to work together. The groove width of the rail and the head shape of the screw must match, which is why systems should not be mixed. Whether the roof can bear the load is a matter for a structural analysis, particularly in the case of ballasted mounting systems.
ACTEC supplies the installation materials but does not carry out the installation. The appropriate solar panels are listed in a separate category, whilst cables, MC4 connectors and tools are found under PV installation materials. The complete PV kits do not include a substructure; this must be ordered separately to suit the roof. Further information about the manufacturer can be found at K2 Systems.
For photovoltaic systems and their essential components, no value added tax is charged where the conditions of Section 12 (3) of the German VAT Act (UStG) are met. You state during the ordering process whether they apply to you.
Frequently asked questions about the substructure
Which roof hooks do I need?
That depends on the roof covering. The range includes roof hooks for various types of tiles, for slate and for metal roofs. Before ordering, check the manufacturer’s specifications for the relevant model to confirm which roof covering the hook is designed for.
Can I combine rails and clamps from different manufacturers?
No. The rails, screws and clamps within a single system are designed to work together. Please stick to a single installation system.
Does the flat roof need to be drilled through for installation?
Not with the D-Dome 6.10: this is secured using ballast. The ballast supports are included in the sets, but the blocks are not.
Is the substructure included in the complete PV kit?
No. The kits contain modules, inverters and, where specified, the storage unit. You can select the appropriate substructure for your roof here.