I've heard nail polish remover (acetone) will clean the panels
USe 1/2 vinegar and water
Window cleaner works just fine. Just don't use anything abrasive like sos pads, etc.
Hi Judy: Cleaning the solar panel is quick and easy. Brush off any loose debris with a damp paper towel, then proceed to gently wipe the surface of the panel to remove any cloudy buildup. Applying a small amount of dish soap to the surface of the solar panel and using a damp cloth might help to remove cloudiness.
If that doesn't help, try this site: https://www.hunker.com/13416343/how-to-clean-cloudy-plastic-to-fix-a-solar-light-cell