Potential photovoltaic (PV) production from vertical facades facing the four cardinal points of the compass are calculated from daily average vertical global insolation readings measured in Burgos, Spain. Ten-minute data sets are collected over forty-five months, from January 2014 to September 2017, in the experimental campaign to produce estimates of daily average insolation levels, from which the PV potential of the vertical surfaces was calculated. Given the scarcity of data on Global Vertical Insolation (GVI), the main sky-related variables were processed in four classic decomposition models (Isotropic, Circumsolar, Klucher, and Hay) to predict the insolation values. Both the experimentally measured GVI values and those calculated with the models were then compared using the statistical indicators RMSE and MBE. The results highlighted the economic viability of Building Integrated PhotoVoltaic (BIPV) facilities, even on the north-facing facades, in comparison with the horizontal facility at the same location.