Abstract

In high-density cities, limited roof and ground areas constrain conventional photovoltaic (PV) deployment. Vertical bifacial photovoltaic (bPV) modules offer an alternative by making good use of building and infrastructure surfaces while harvesting irradiance on both sides. This study develops an integrated module-level framework for evaluating tilted and vertical bPV modules. It couples two-sided anisotropic irradiance calculations with five-parameter electrical and steady-state thermal models. Unlike irradiance-only or configuration-specific assessments, the framework consistently compares bPV and monofacial PV (mPV) modules across tilt and azimuth configurations while jointly quantifying power output, module temperature, bifacial gain, and angular losses. Predicted power output agreed well with outdoor measurements across four representative mounting configurations, and annual predictions were comparable to PVsyst and SAM results. Applied to Hong Kong, the framework identified optimum tilt angles of approximately 20° for bPV and 18° for mPV modules. A vertical west-facing bPV module achieved 96.3% of the annual energy yield of optimally tilted mPV, with a bifacial gain of 67.2% and an angular-loss-related power loss of 4.8%. These results show that vertical bPV can approach optimally tilted mPV performance while utilizing otherwise unused building surfaces, supporting preliminary design decisions in land-constrained cities.

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