1) The Harbor Freight panels are "film" panels. Notice that they don't have any silver grid traces across any of it.
2) Mono or polycrystalline cells are different and original tech. Notice the grid wires across each cell.
Film: Shading such as a branch or cable, or even wet-leaf across a film panel only puts the shaded part out of commision - the rest still works. Technically, the shaded portion is reverse-biased, but the part of the film panel that is exposed to direct light is able to pass current past the shaded parts easily.
Mono/Polycrystalline:
Shading just one of these cells put the cell into reverse-bias. Since it is wired in series with the rest of the other cells, it can totally inhibit the current coming from the exposed cells. In most cases, current *will* pass through it, but not fully, and but being reverse biased that shaded cell gets hot.
What most modern panels do is actually wire the panel into two "halves" or in effect electrically two-panels in parallel separated by blocking diodes inside the junction box.
So, now, when a shadow, wet-leaf etc puts a cell into shadow, only half the panel current will try to pass through the reverse-biased shaded cell, so the cell lives longer in that reverse-bias condition.
It's a very wordy way to say that mono/poly panels should not be shaded at all, whereas film-type panels can handle that condition better. Ie, a mono/poly panel with slight shading can result in severely degraded current until the shadow passes.
Note that I have not gone into any sort of film vs mono panels for longevity, build quality etc. But if you are not going to babysit or do a site-survey of shadowing, especially in long-shadow winter conditions, then a film panel might be your best bet. Would I put film panels as a long term solution on my house? Not currently as film panels degrade faster than mono/poly panels.
For me, film is camping / hobbiest stuff - and can do very well. Permanent 20 year installations? Mono/Poly currently.
All of this can be proven easily by the hobbiest by merely placing a piece of cardboard over a mono panel and a film panel, and taking measurements.
Moral: try not to shadow *either* of these different tech panels.

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