Abstract

Shading systems improve building energy performance and occupant comfort by controlling glare, natural lighting, and solar gain. Integrating PV (photovoltaics) in shading systems opens new opportunities for BIPV (building integrated photovoltaics) on façades. A key problem of such systems is mutual shading among PV modules as it can lead to electrical mismatch losses and overheating effects. In this work, we present a new modeling framework, which couples parametric 3D with high-resolution electrical modeling of thin-film PV modules to simulate electric energy yield of geometrically complex PV applications. The developed method is able to predict the shading pattern for individual PV modules with high spatio-temporal resolution, which is of great importance for electrical system design. The methodology is applied to evaluate the performance of different dynamic BIPV shading system configurations, as well as its sensitivity to façade orientation and module arrangement. The analysis shows, that there is a trade-off between tracking performance and mutual shading of modules. Distance between modules is a critical parameter influencing the amount of mutual shading and hence limiting solar irradiation and electricity generation of PV shading systems using solar tracking. Planning of module string configuration, PV cell orientation, and location of bypass diodes according to partial shading conditions, reduces electrical mismatch losses and results in significantly higher electricity generation. The integration of parametric 3D and electrical modeling opens new possibilities for PV system design and dynamic control optimization. Though the analysis focuses on BIPV, the method is useful for the planning and operation of solar tracking systems in general.

Abstract

During the last two decades several integrated tools have been developed to make the existing scientific knowledge available to river managers and assist them with the formulation and evaluation of alternative combinations of measures. Yet, few practical examples of embedding of these instruments in river management organizations can be observed so far. This paper identifies the possible organizational, technical, and scientific factors that may form an obstacle for the design and application of a Decision-Support System (DSS) for river-basin management by analyzing the interaction between the different participants in the Elbe DSS project. In particular attention is paid to the software engineering aspects of the design process. In order to start an integrated approach to deal with conflicting river strategies a project to develop a prototype tool for integrated management of the Elbe catchment was initiated, which includes functionalities related to inland navigation, water quality, flood safety, and vegetation ecology. The problems faced in the German part of the Elbe catchment range from poor navigation conditions and flooding vulnerability to a need to restore and maintain the natural state of the floodplains. Several river engineering works such as large-scale dike shifting, channel dredging, and large-scale retention are in a planning or implementation stage. From the beginning of the project onwards attention was paid to the involvement of potential end-users and key stakeholders in the design process. The experience of the project is that internal consistency of models and data, effective communication, and functional flexibility are essential to warrant a proper balance between scientific standards, the availability of models, and the requirements of users. This facilitates the design process and improves the chance of successful implementation.