This is a very simple question, but I haven't found the answer yet. It seems to me that monocrystalline panels are always black (though I have seen some dark blue ones), and polycrystalline panels are bright with lots of patches of different shades of blue. However, I've seen some panels that still seem to have the patches but they are very dark overall. Is there a proper way to tell what kind of panel one has just by the looks? is the presence of shades/patches of blue a good indicator of a panel's polycrystalline structure no matter how dark they are? or for that matter, are monocrystalline panels always black?
Thanks in advance.