Problem:

When fitting parameters there seems to be a systematic bias with irradiance, typically increasing. This may be caused by PVMismatch's constant shunt resistance. Other models such as SAM/DeSoto 5-parameter or PVSyst have a shunt resistance that is a function of irradiance.

Shunt resistance

PVPVMC on De Soto “Five-Parameter” Module Model

Rsh = Rsh_0 * E0 / Ee

Note: irradiance is in the denominator so as irradiance increases the shunt resistance decreases.

Proposal:

add a factor to account for irradiance bias base on DeSoto 5-parameter model