API field
Voc temperature coefficient (specified)
Change of the open-circuit voltage per degree; used for string sizing only
Unit mV/°C
What it is
How much the open-circuit voltage changes per degree of cell temperature. The field is in millivolts per degree; the API takes volts per degree. The circuit model produces its own voltage-temperature behaviour, so this value is used only by the string sizing check on the System tab.
Typical values and how to get it
The datasheet value: about −0.24 to −0.30 %/°C of the open-circuit voltage for current crystalline modules, roughly −120 to −150 mV/°C for a 50 V module. If not given: the string sizing check on the System tab uses the power temperature coefficient times the open-circuit voltage, μ_Pmpp × V_oc, in its place. The run does not use this value.
API
module.beta_voc — sent in V/°C