Solar installations on flat roofs need more ballast if, for example, they are fragmented due to skylights or atriums. In many cases, the load reserves on flat roofs are very limited. Linear mounting systems that distribute the loads through rails are difficult to build around skylights. Pointed support systems where the panels are only linked by their frames are more unstable. Here, strong wind forces can cause individual solar panels to shift.
Detailed wind tunnel tests
With the help of detailed wind tunnel tests and the resulting static calculations, the Ernst Schweizer AG reduces the ballasting of their mounting systems to a minimum. Instead of floor rails, they use base plates of variable contact surface for the substructures of the MSP series. The stabilisation is provided by rails that are bolted to the supports in a north-south and east-west direction. The first part of this series explained this approach and its advantages.
In addition to saving on material, installation time and money, the mounting systems in the MSP series are much more flexible than the standard rail systems on the market. On the one hand, the east-west and the south-facing system can be combined as desired. In addition, individual panels can be omitted without any problems, so that the substructures can also be built around skylights, atriums or anchor points without cutting.
If the solar installation is very fragmented, this can have a major impact on the design; more ballast has to be included. The Ernst Schweizer AG uses the software proMSP for their calculation. It divides the panel array into blocks and determines the specific wind load for each individual panel. The necessary ballasting also depends on the specific weight of the solar panels as well as on the snow and wind loads. (author: Dr Helge Hartwig)
Dr Helge Hartwig is Head of Sales and Technology for PV mounting systems at Ernst Schweizer AG.
Read this about Ernst Schweizer AG, too:
http://www.pveurope.eu/News/Installation/Module-installation-Stable-systems-for-all-roofs
http://www.pveurope.eu/News/Installation/Sjef-de-Bruijn-from-Ernst-Schweizer-AG-We-have-to-be-very-efficient
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http://www.pveurope.eu/News/Installation/Advanced-mounting-solutions-for-British-and-Irish-roofs
http://www.pveurope.eu/News/Solar-Generator/PV-Guided-Tours-More-roofs-fewer-parts
http://www.pveurope.eu/News/Installation/Solrif-in-roof-systems-for-housing-projects-in-England
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