Question about PowerOak Solar panel

for 1 single panel 12 A max = 2.5mm2, so 4mm2 = ok and minimises the voltage drop over 10 metres
Be careful if you put several panels in parallel the current (A) is added = always 36 V but 12 A + 12 A = 24 A so 8 or 10mm2 cable
Be careful if you put several panels in series the voltage (U) is added = always 12 A but 36V + 36V = 72V so 4mm2 cable always ok
Bye

P =U*I

P= 420 W
U= 36 V
I= 11.6666666 A

36*11.66666 = 420W

420W/36= 11.66666 A = 2,5mm2 Minimum