@NeverDie
I clean my solar lights with:
Cloth (2 pcs)
Sponge
Dish soap (a few drops)
Regular 3% hydrogen peroxide (1 gallon)
Oxy laundry booster (1/4 teaspoon)
Bowl of water
Another bowl for the peroxide or the same bowl without the water
Rubber gloves (1 pair)
UV light or sunlight
Paper towels
Plastic wrap (optional)
Tape (optional)

Like other lamp owners, I don't clean them as often, but at least twice a year. I want my solar lights to be perfect every time I use them.

I think cleaning yellowed plastic solar lights is an important part as outdoor .rust prevention of its maintenance and because I want my own set of lights to last a long time, I make sure to keep up with its cleaning to avoid excessive oxygenation once more.