If you do not have access to a water source (hose or pressure washer) I would fill a bucket with warm water and car soap. Then fill a spray bottle with solution from the bucket. Pre soak the panel and wash with a wash mitt or microfiber. Dry with a waffle weave.
I say you "can" do a WW method on this... ONLY if you REALLY soak the panels, and maybe every 1/2 wipe you stop and change your edge on your towel.
All about technique in this case.