EU PVSEC 2014 22-26 Sep 2014, Amsterdam, The Netherlands Paper submission Topic: 6. PV Applications, Subtopic: 2. PV as Building Material Component (Oral presentation with Peer Review) Reflection from PV facades and roofs – New assessment methods based on annual weather data Stephen WITTKOPF 1* , YANG Xiaoming 1 , XU Ran 1 1 Lucerne University of Applied Sciences and Arts Technikumstrasse 21, 6048 Horw, Switzerland *stephen.wittkopf@hslu.ch Abstract This paper presents a method for the assessment of reflections from PV facades and roofs during the architectural design. Using a 3D CAD model of the BIPV building and the potentially affected neighborhood, as well as reflection properties of the Photovoltaics and annual local weather data, it is possible to locate the spots in the neighborhood that will be most affected by the reflections, predicting their frequency, quantity and origin of light. Such tool and the related consideration in an integrated design process with all stakeholders will help to objectify the impact and acceptance of Photovoltaics in the built environment. Keywords: Façade reflection, Radiance, Reflection Simulation, BIPV Introduction With the increased desire and drive to enter the 2000 Watt society, solar panels have become an indispensable contribution when it comes to renewable energy. Nowadays, reflections from solar panels are being addressed, resulting in concerns for the neighborhood in the proximity of the solar panel, since reflections can cause glare, whose consequences can vary from mild visual discomfort to temporary blindness. This phenomenon is strongly linked to safety in cases involving pilots [1-4], car drivers and pedestrians. One of the most famous reflection problem is the one that is caused by the Walt Disney Concert Hall in California [5]. The discomfort was due to the façade material and curvature choice made by the architect. This example shows the importance of integrating the reflection simulation process in the early design phase to avoid similar problems in the future. Several researches have tried to predict the reflection. Some have developed a simple software, which can produce a reflection graph that implies the reflection points and the reflection hazard area [6]. This method does not take the material properties of the Photovoltaic module into consideration, and only direct sun beam is taken into account. Others used 3D animated simulation for selected key glare points to decide the risk of glare on the days of summer solstice, winter solstice, fall equinox and spring equinox [7]. Even though the reflectivity of Photovoltaic material is much lower than glass, glass characteristics are still assigned to the Photovoltaic in the 3D animation so as to get the result of the worst case scenario. Some used a dynamic simulation method by simulating the reflection beam