Pressure equalization and wind loads on roof-mounted solar arrays

在过去的几年里，加拿大安装的屋顶光伏(PV)阵列的数量有了很大的增长，在过去的十年里，全球的光伏阵列几乎增加了三倍。风通常是主要的设计荷载，但目前建筑规范中没有针对此类荷载的适当规定，如何处理这些荷载存在很大的不确定性。准确了解这些负载对于在现有屋顶上安装光伏阵列尤为重要，在现有屋顶上，可用结构容量往往有限，无法承受阵列的额外重量和压载。重要的是要解决这些问题，以便将太阳能发电更多地渗透到郊区和城市地区。 安装在屋顶上的太阳能电池板依靠一种名为压力均衡的空气动力学机制。这意味着屋顶安装阵列上的设计风荷载应该比作用在屋顶结构上的风荷载小得多。建筑物上的多层覆层系统也依靠压力均衡来减少这些系统需要承受的负荷。然而，对于建筑物的风荷载，压力均衡是一个重要的悬而未决的问题。因此，虽然最大限度地实现压力均衡是可取的，但目前只有有限的理论来预测或模拟这一现象，而且现有的公式中缺少关键参数。为了能够优化设计和建筑规范方法，需要更多的信息。 因此，当前提案的目标是(I)开发压力均衡的分析模型，以及(Ii)将结果应用于屋顶安装的光伏阵列的情况。这项工作是在申请人的研究计划的背景下进行的，该计划的重点是开发更好的结构在极端风中的载荷和响应的设计标准和模型。将进行新颖的实验，使用为“三只小猪”项目开发的技术。至少有六名研究生和几名本科生将接受这个项目的培训。

There has been a substantial increase in the quantity of installed roof-mounted photovoltaic (PV) arrays in Canada in the last few years and an almost threefold increase globally in the past decade. Wind is often the governing design load, but currently there are no appropriate provisions in building codes for such loads and there is a great deal of uncertainty about how to handle them. Accurate knowledge of these loads is particularly important for the installation of PV arrays on existing roofs, where there is often limited structural capacity available to withstand the additional weight and ballast of the arrays. It is important to resolve these issues in order to have greater penetration of solar power generation into suburban and urban areas. Roof-mounted solar arrays rely on an aerodynamic mechanism called pressure equalization. What this means is that design wind loads on roof-mounted arrays should be substantially less than those acting on the roof structure. Multi-layer cladding systems on buildings also rely on pressure equalization to reduce the loads that these systems need to withstand. However, pressure equalization is a significant unresolved issue of wind loading on buildings. So, while it is desirable to maximize pressure equalization, there is currently only limited theory to predict or model this phenomenon, and key parameters are missing in existing formulations. In order to be able to optimize design and building code approaches, much greater information is required. Thus, the objectives of the current proposal are (i) to develop an analytical model for pressure equalization, and (ii) to apply the results to the situation of roof-mounted PV arrays. This work is done in the context of the applicant's research program, which is focussed on the development of better design standards and models for the loading and responses of structures in extreme wind. Novel experiments, using technology developed for the 'Three Little Pigs' Project, will be conducted. At least six graduate students, and several undergraduate students, will receive training on this project.