39 shades of suitability: Case study of metrics for urban photovoltaic assessment in zurich Switzerland

Photovoltaic (PV) systems are crucial for reducing greenhouse gas emissions, and their deployment in urban environments is seen as a promising direction towards increasing renewable energy generation. However, the urban context unfolds as a heterogeneous fabric, making the assessment of building-integrated PV (BIPV) suitability more complex than for free-standing systems. Furthermore, prior studies suggest that the suitability of BIPV installation, in a quantitative sense, depends on the perspective of the suitability assessor (i.e. maximising environmental benefit or financial benefit). This study therefore applies 39 common PV suitability metrics from the literature to simulation results of 33 BIPV system variants modelled on a small urban block in Zurich, Switzerland. Metrics included are of technical (e.g. yield), economic (e.g. levelised cost of electricity), environmental (e.g. total greenhouse gas emissions abated), and systemic (e.g. self consumption) nature. Results of hierarchical clustering and correlation analyses indicate the mutual influence between system traits, cell type and electrical architecture, the assessment metric considered, and surface orientation. In further analysis, the metrics were clustered using a hierarchical approach to form data-drive groups amongst each of the surface orientations. When comparing the clusters there are clear differences between the clustering of different metric rankings. Furthermore there are very clear instance s of spatial sensitivity for several metrics, particularly between roof and east-facing surfaces. This study highlights the significant differences in metrics, demonstrating that PV system suitability is a matter of perspective, and that PV deployment in urban environments should not be solely based on singular metrics such as annual yield.