Dear Federico,
I haven't seen the problem your addressing but you can check the following things perhaps to make sure everything is correct:
- Make sure the temperature coefficient is given in V/K (as normally it is given as %/K in datasheets)
- The component is designed so that if no "Load Voltage" input parameter is chosen zero, it assumes you have connected a mppt charge controller and thus only the Pmpp, Vmmp, Impp are correct to be used. If you however have determined a load voltage > 0 V (like direct connection to a load) then probably the Parray, Varray, Iarray will follow the load.
Make checking this two things can help you sort out the problem.
Kind regards,
Michel