Glass rooflights that are installed in flat roof applications can be susceptible to staining and dust build up through rainwater and other things such as bird droppings and tree sap and leaves so they will need cleaning just like any other window in your home, however getting access to rooflights can be problematic. Installing the rooflight at the recommended pitch will help to keep the glass clean as this will help rainwater to run off the surface naturally, but there are other things you can do that will improve the look of a rooflight that is fitted in a roof.
Probably the best method of cleaning is by regularly washing the glass using a solution of warm water and mild detergent remembering that surfaces should be cleaned using a soft cloth or sponge, with any stubborn stains removed using a natural bristle brush. No abrasive cleaners should be used as it may affect the powder coated frame and glass finish of the rooflight.
To reach the rooflight, a telescopic brush with an angled head can be used which may mean that a ladder will not be necessary. A professional window cleaner may be able to clean the rooflight for anyone who is not able to do this themselves.