![]() ![]() On commercial buildings a 4 m gap is typical. On domestic residences it is useful to maintain a 1 m gap between the roof edge and the array. Installation and maintenance personnel need to be able to access the roof, move safely about on the roof and access the solar PV array from all sides. Note that parapets can reduce the wind load on nearby solar PV arrays but can also increase shading. Commercial solar PV installations require more time and traffic on the roof than domestic installations - the thicker cladding offers a lower lifetime cost. Sheet metal roof cladding with 0.48 mm BMT will be more durable than the 0.42 mm BMT commonly used on domestic residences. ![]() Membrane roofs are not recommended as they are very difficult to fix through. This requires the building to use standard sheet metal roof cladding. The simplest, fastest and lowest total cost method is to fix the solar PV frame to the building frame using standard roofing screws. Typically, uplift governs the design of the solar PV frame and its method of attachment to the building frame. Either SunLock or our partner Gamcop structural engineers can assist with these calculations. Furthermore, tilted PV arrays are subject to larger wind actions than flush mounted arrays. Different zones of the roof are exposed to different loads. Wind loadĪ solar PV array is subject to wind actions (uplift or down force) defined by AS/NZS1170.2. In these cases the purlins and rafters will need to be upsized. However, some large cost-optimised commercial buildings may be limited by a combination of static load and wind down force. ![]() Typically, this won’t impact the design of the building frame as the frame will already have capacity to withstand a live load of 25 kg/m2. Static loadĪ solar PV array will increase the static load on the roof by 10 – 15 kg/m2. Note that a solar PV array should be inclined at least 10° above horizontal to allow rain to clean the modules and to prevent the buildup of dirt or deposits. The ideal roof pitch is 10° to 30°, as it is cheaper and easier to install a solar PV array flush (or parallel to) the roof than to use a tilt frame. Therefore, building designers should allow for this scenario. Such installations are already common in Europe and the USA. As market for solar PV matures, building owners may wish to cover the entire roof with a solar PV array. ISSUES TO CONSIDER Roof coverageīuildings can last more than 100 years. This technical bulletin is intended to assist architects, building designers and structural engineers to design solar ready roofs. A “solar ready roof” will simplify the later installation of a solar PV array. ![]()
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