Solar Collectors and Other Roof Mounted Structures
Solar energy collectors, Heating Ventilation and Air-conditioning (HVAC) systems may be attached directly to the surface of profiled metal roof cladding or mounted on a frame above the roof plane.
For direct fastened solar energy collectors, a complete seal between the photovoltaic (PV) cells and the cladding is essential to prevent water ingress resulting in wet storage corrosion.
Rail mounted systems for solar energy collectors can be installed in a similar manner to HVAC systems and other roof mounted structures. Units may be laid parallel to the roof or oriented at an angle for greater efficiency and easier roof maintenance.
Support frames installed above the roof must have sufficient gap underneath
- to assist with self-cleaning,
- limit the build-up of leaves and other debris,
- provide access for inspection and cleaning, and
- allow air movement to quickly dry areas under the panel.
The minimum recommended gap is 100 mm from the pan, and 20 mm from the crest of a profile. A greater clearance may be required for larger installations or where greater debris deposits are expected.
The support structure may be connected to the rib of clip fixed products; or supported by the rib and attached through the profile to the purlins. The designer must ensure that the design of the roof and the structure is adequate to resist any additional wind and gravity loads associated with the panels.
Access to the roof for inspection and maintenance must be considered when designing roof mounted structures. The roof cladding should be designed to resist regular roof traffic, or the installation of walkways is recommended.
Wires and conduits penetrating the cladding must be fitted with a gooseneck or proprietary cover to prevent reliance on sealant for weatherproofness and must be installed so that their base does not impede water flow.
Supported HVAC Installation
Support structures must be constructed of materials compatible with the roofing material and separated from the roof by a non-absorbent and non-conductive rubber gasket. Typical proprietary support structures are manufactured from aluminium with stainless steel fasteners. Contact between the stainless fasteners and the roof cladding should be avoided, but run-off is acceptable. Contact with, or run-off from, copper onto painted and unpainted steel and aluminium roofs must be avoided.
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