Yes. The half-cut cell panels are something I have not dug into (I have not used them so I have not had a need).
As I understand it, the two zones of the half-cut cells are wired in parallel. Is that correct? Do you happen to know if there are blocking diodes between the two zones? This would help prevent the shaded half from pulling down the other half.
The other thing I wonder about the half-cut panels is what happens when 2 or more of these are in series and half of one is shaded. In this case, one panel will produce about 1/2 the current of the other..... I think that means it will cut the whole string current in half. (As I type this, I am wondering if some of the new panels with really high Voc (>60V) are half-cut with the 2 zones wired in series? )
All of this adds up to this: If you are going to have shading, it is important to know how your panels work and lay them out to minimize the impact of the shading.
I’ve got half-cut panels.
They are two half-panels connected in parallel and sharing a common set of three bypass diodes.
So with just one panel, if one half panel has shade impacting 2/3 of the columns, that panel will operate at 50% max power (full Vmp with 1/2Imp).
If one half panel only has shade impacting 1/3rd of the columns, the bypass diode will activate for 67% max power (2/3Vnp with full Imp for both half-panels).
If there are 2 half-cut panels in parallel, shade completely blocking a single half-panel will result in 75% max power (3 out of 4 half-panels at full Vmp and 1/2Imp). No bypass diodes activated.
If 2/3 of the columns of a single half-panel are blocked by shade, the parallel string will continue to operate as above since activating 2 bypass diodes would reduce output power of the shaded panel as well as the shorted unshaded panel in parallel to 33% of max resulting in only 33% power for the full 2P string (less than that available by operating at full Vmp with only 3 out of 4 half panels contributing 1/2Imp).
And the same will be true if shade is blocking only 1/3 of one half-panel, a single bypass diodes activating would resulting in 67% full power from both the partially-shaded panel and the unshaded panel, less that the 75% available by operating at full Vmp with 1-1/2 Imp (so the MPPT controller will prefer to operate at Vmp for 75% max output).
Put those same 2 half-cut panels into a 2S series string and the impact of shade affecting a single half-panel will pretty be identical to what you’d get with standard (non-half-cut) panels.
If shade completely blocks one half-panel, total power is reduced to slightly more than 50%. Because only 1/2 Imp flows from the partially-shaded panel (with voltage of Vmp), the second unshaded panel is limited to that same 1/2 Imp of current. Because each half panel is only passing 1/2 Imp, voltage across the unshaded panel will increase above Vmp (hence the >1/2 Wmp power output from the second panel).
A 2S string of half-cut panels behaves like a standard panel if shading on one half-panel is only blocking 1/3 of the columns. In that case, 1 bypass diode will be activated delivering full Isc at 2/3Vmp from the partially-shaded panel meaning total 2S string voltage will be 5/6ths of what it would be without shade, or 83.3% (superior to the 75% of the 2P string).
And shade impacting 2/3 of one half panel will activate 2 bypass diodes, resulting n 67% of the maximum (unshaded) output for the 2S string (inferior to the 75% of the 2P string).
The main advantage of half cut panels in shade is that you can go massively parallel allowing all half-panels to operate at Vmp from a single MPPT getting full power from any unshaded half-panels in the full parallel string…