In the fabrication of dye-sensitized solar cells (DSSC), dye coating is a time-consuming and critical step. Rapid sensitization processes suitable for DSSC industrialization require appropriate dye loading measurement methods. We present a non-destructive method, in which we monitor a fast continuous flow dyeing process by UV-Vis analysis on the exhaust solution flowing out of the cells. The proposed approach has the advantage over a direct optical analysis on the photo-anode of being independent from film non-uniformity, transparency and area. The monitoring method was successfully applied to evaluate the dependence of Z907 dye adsorption kinetic on temperature, flow rate and dye initial concentration, both on small cells and on 23 cm x 23 cm DSSC modules. Saturation of dye uptake is reached after 40 min for 0.3 mM dye solution and the rate constant is determined to be 0.114 min(-1). The results are discussed and correlated with DSSC photovoltaic performances, showing that a longer coloration time has a beneficial influence on long term stability. (C) 2017 Elsevier Ltd. All rights reserved.