Hi, I am designing a PV system in kW and having a small confusion that should I be considering the solar irradiance in Wh or kWh in the PV calculations?
When you say power it is always energy consumed/created per unit time. Thus it depends on the units you use. Power in fundamental units is expressed joules/sec and thus weather you consider irradiance in W or Wh will depending on units you are using.
The standard practice says irradiance in PV system is considered as Wh/m2 or kWh/m2 . In this case you will have to use the power calculations in kW to consider irradiance in kWh/m2.