So what is the difference between the walnut pad and white pad

The XERO Walnut Pad has crushed walnut shells within its fibers for a more aggressive scrub. The XERO White Scub Pad is a polyester blend that is a softer scrub that works well with polishing, and often used in tandem with Diamond Magic Stain Remover. 

How many times can you use 1 ?

This scrub pad is pretty durable. You can use this pad until it is no longer effective. It really depends on how much and how heavily you are using it.

Are these fine for low e windows?

We would not advise scrubbing on the low-e film side of the glass.

What are these made of?

It is made out of recycled polyester fibers.

Are these safe for windows with film on them?

Hi Jonathan, definitely avoid anything abrasive when cleaning windows with film on them. You want to use something like a microfiber towel or an all microfiber sleeve with NO porcupine needles, NO end scrubbers, NO abrasive pads. Anything abrasive, even something as soft as the Mr. Clean Magic Eraser will damage the tint.

How thick is this pad?

It is 0.375" thick.

What is the thickness of this paf.

Hi Robert, they are 0.375" thick.

Are these safe to use on solar panels?

Yes the white pad is safe on solar panels.