b'CLEAN ENERGY Wind pressure resistance of PVRA link between the strength (design load) and capacity (resistance) There are several different types of PV infrastructural systemsof the PVRA rather than assuming that these failures are the forlow-slopecommercialrooftops,producedbyvariousoutcome of highly unusual wind events.manufacturers. These systems are differentiated by the typeCurrently, there are no standardized test methods that deter-of framework used to support the modules and mechanismsmine the collective performance of the PVRA. The existing test used to hold them to the roof. In general, the PV infrastructuralmethods either focus on PV modules electrical and durability systems on rooftops can be classified into four primary types: or a simple static load method to test the racking system.Hereballasted support structureracking system supported by ballast,is a snapshot taken from the Structural Engineers Association fixed or penetrated support structureracking system mechanicallyof California (SEAOC) PV2 document Wind Design for Solar Array that highlights the importance of a dynamic test method fixed to the structural deck,to understand the actual behavior of roof-mounted solar panelswelded support structureracking system attached to the roof For example, we are not aware ofany research that defines a relationship membrane by hot-air-welded flange, between the wind loads calculated in this report (for structural design ofthehybrid systemracking system supported by a combination of racking system) and the loads used in static loading tests such as UL1703, ballast and penetrated support structure. Standard for Flat-Plate Photovoltaic Modules and Panels (for evalu-All of these attachment methods have different implicationsating performance ofmodules). One concern that has been raised is that concerningthewindperformanceoftheroofingassembly.the effects ofcyclic and spatially variable wind loads are not captured by First, the PV systems load transfer to roof assembly affectsthese static tests.theroofassemblyswaterproofing,durability,thermaland structural integrity. And second, the failure of the PV systemPVRA research study and CSA standard developmentunder wind loads damages the roof assembly. For commercialIn collaboration with the roofing and solar industry (RCABC, roofs to successfully accommodate as a support platform forNRCA,CRCA,ARCA,Soprema,SikaSarnafil,GAFand solar arrays, it is critical that additional technical aspects ofCANSIA), NRC is conducting a research study to address the the combined PV system and roof assembly, PVRA, must bemissing link between the design and resistance of the PVRA. considered rather than as separate entities. This will ensure theThis study has three major tasks. long-term performance of the PVRA.Underwindaction,animproperlydesignedPVsystemTask 1 focuses on developing a dynamic test method to could undergo failures (see Figure 3) such as flipping or slidingevaluate and quantify the critical wind effects on PVRA, i.e., of panels, sliding of the array, modules disengagement frominternal forces in PV support systems, reactions on the roof the racking and clamp disengagement between the modulesassembly and uplift or sliding of the PV system. puncture of the roofing membrane. When these kinds of fail- Task 2 quantifies the PV systems adverse effects on the ures occur, it should be seen as a clear warning of the missingroofing assembly serviceability. BUILDrogressive ustainable uilding MOREP& sbe nveloPee ngineerings olutions WITH BEACONn ewC onstruCtion. r estoration. r e - roofingbeacon-canada.comd ePreCiationr ePorts. a nnuali nsPeCtions & M aintenanCeM anualsHIGH-RISE . CONDOMINIUM TOWNHOUSE . COMMERCIAL INSTITUTIONAL . SINGLE FAMILY12510 82 Avenue, Surrey, BC V3W 3E8www.aqua-coast.caTel: 604.946.9910201-5155 Ladner Trunk Rd., Delta, BCV4K 1W4 314 Totom Avenue, Kelowna, BC V1X 5C2www.rcabc.org l21'