How do I clean solar lights?

Clean carefully with a soft cloth and white vinegar.

I would dilute a little vinegar and rub it onto the lense to see if it will wipe away. Test it in a small area first.

I agree with the diluted vinegar mixture. Vinegar can work magic sometimes.

White toothpaste

The solar collector is meant to be exposed to the elements but requires regular cleaning. I would only use water on it. You don't want anything abrasive. A few drops of a neutral soap would be fine if you have stubborn dirt.