What SPD ratings to use?

[ragnakore]

Hi all!

What should be the proper SPDs for DC and AC application?

DC SPD: MPPTs are rated 500V
PV+ to PV- measures 300Vdc ~ 400Vdc
PV- to PE/GND measures -200VDC
PV+ to PE/GND measures +150VDC
Is SPD with a Uc of 500Vdc the correct one?
What if either PV+ or PV- is shorted to N? What should be the correct SPD to use?

AC SPD: L1-N = 120Vac, and L2-N = 208Vac
Is SPD with a UC of 275Vac the correct one?

In general what is the correct SPD ratings?

Thanks!