In both electrolytes, the experimental RMSE values are expectedly higher than those obtained numerically for the total vanadium concentration and slightly higher for the SoC. These results highlight the strength of configuring the wavelengths of an optical absorbance sensor for RFBs, showcasing the potential design improvements that could be made. We demonstrate that calibration errors close to the full spectrum can be achieved using fewer than 6 channels. Nonetheless, we acknowledge that part of the difference between optimal and experimental RMSE could be partially due to experimental errors (sample preparation, spectral distortions). In addition, our experimental sensor only detects wavelength up to 680 nm compared to the 900 nm limit provided in the optimization. With a limited number of channels, these spectral distortions might be difficult to detect, which could pose challenges for recalibrating the sensor. Despite these limitations, these results provide a guide for future sensor designs.