Given that solar cells are coated with an anti-reflective (AR) coating and that the colour of this layer correlates very well with the thickness of this layer, the measured colour can be used to monitor process characteristics of solar cells.
The Arges 45 is an integrated measurement system which doesn't require any additional components to measure the colour of solar cells for both appearance reasons and as a cost effective solution to monitor solar cell process characteristics which relate to the efficiency of the cell.

AR-coating layer thickness versus colour. Represented in CIE L*a*b* colour space.