How are you cleaning your metal panels including organic material, baked on film or graffitti?
We recommend mixing a ¼ cup of detergent, which can include car washing soap or mild dish soap, with a gallon of water. Then, you'll just need to apply to solution to your metal roof with a sponge, microfiber cloth, or soft-bristle brush, and let it sit on the surface for 5-10 minutes.