Sky view factor (SVF) measures the openness of a point to the sky vault and as such, has been widely used in urban climatology and environmental design studies associated to various phenomena, including Urban Heat Island intensity and daylight availability. This study examines to what extent SVF can be also employed for predicting solar availability in the urban environment, with emphasis on building façades. SVF and solar irradiance simulations were performed for vertical façades in 24 urban forms -of 500x500m areain London; mean values were computed by urban form, and by façade orientation, considering 30 orientations at 12° azimuth intervals. The statistical analysis reveals a strong linear relationship (R2 >0.8) between SVF and annual global irradiance for all orientations. The models derived from linear regression tests were integrated into a graphical tool for predicting annual global irradiance on a façade in London as a function of its SVF and azimuth angle. Furthermore, the fact that SVF was found to correlate well with both major components of solar irradiation, namely direct and sky diffused irradiances, indicates that it can be used for predicting annual solar availability at latitudes similar to London, even for sunnier climates.