ROOFS AS EXTENDED SURFACE SOLAR COLLECTORS: PRACTICAL ISSUES AND DESIGN METHODOLOGY

For most typical houses, roof surfaces represent the major opportunity for solar energy collection. Their nature provides a high level of design flexibility since their slope can be adjusted to a great extent without compromising the shape of the living area. However, in reality many constraints and practical considerations come into play, including snow accumulation, differential pricing, structural costs, construction methods, and solar collector types and their available sizes. Thus, roof design for solar energy collection is complex and presents itself as a time-consuming step in house design. In order to minimize design time, a design tool is being developed to allow for an integrated design procedure. While this paper focuses on building-integrated photovoltaic (PV) panels, the methodology is intended to be applied to other types of solar collectors including solar thermal and combined photovoltaic/thermal collectors. The first part of this paper presents an algorithm for efficient whole-year performance predictions accompanied by validation and a sensitivity analysis. The second part of the paper addresses a comprehensive list of practical roof-integrated PV array issues and how they can be implemented into a new design tool, such that roofs can be efficiently designed. Finally, a high-level methodology for roof design is presented.