What solar panel specs are used for calculating voltage loss

MrWizard wrote:
right now the sun is NOT quite STC
i am under partial shade, sun only on front panels
other panels fully or partly shaded (leafy shade NOT deep shade)
i just measured 18.88 amps @ 14.31v as controller output
input voltage measured at 15.45v

we don't know how the IP curves were created, but unless it was on a known calibrated load that we can compare too (which is not stated)
I think it was probably measured on a short circuit or directly connected to a battery

Very interesting! Would you call that 1.14 volt drop in the controller "line loss" except not in the wire paths to and from it?

The controller will have some sort of R