Solar panel soot math had me laughing at my own roof in Portland

Read that a single 300W panel covered in 5 grams of soot can lose like 25% output, so I weighed a dusty paper towel and yeah, I've been shading my own savings this whole time. Anyone else check their panels after a dry stretch and find a legit science experiment up there?

2 comments

2 Comments

mark_carr71mo ago

Did you actually measure the output before and after cleaning, or are you just going off the dusty paper towel weight? Because I keep seeing people quote that 25% number, but I feel like it has to depend on the angle of your roof and how much rain you get. Portland gets enough drizzle that I figured most of it would wash off, but if you're seeing a legit film up there after a dry stretch, that's wild. I'm curious if you found the loss was worse on certain panels or if it was pretty even across the whole array.

ruby_henderson361mo ago

Wait, is 25% actually a real number people throw around, or did I just convince myself my dusty panels were fine because I forgot to clean them for a year? I mean, I didn't measure anything, I just wiped one and felt like a detective who'd found a crime scene, haha.