ters
Electrical
- Nov 24, 2004
- 247
I’m tasked to compare two 1MW PV inverters. One of the items which seems to be rather difficult to compare is the efficiency. One unit is specified with CEC (California) weighted efficiency, while for the other one European weighted efficiency is provided.
I know that inverter efficiency, aside from the type and quality of electronic components used, also depends on the DC voltage, inverter output power and ambient temperature as well, but I don't know how it is actually measured according to various standards.
So after doing some research, I determined that CEC efficiency is calculated as an average value of DC/AC conversion efficiency at six pre-defined outputs between 5 % and 100 % nominal power, while calculation of European-weighted efficiency is more fuzzy and seems to be somehow determined from several efficiencies at different operating points that are weighted according to the frequency with which they occur at a specific location somewhere in Europe.
Web sources which compare the above two methods/standards of calculating PV inverter efficiency and provide some sort of conversion seem to be non-existent, while some inverter manufacturers occasionally do give efficiencies according to both standards, where more often than not “European" efficiency is higher than the CEC one, for example CEC-weighted is efficiency of 97.5% is sometimes given as 98.1% European-weighted. However, examples where this is oposite also exists, for instance one partular make and model of the inverter has CEC efficiency of 97.00% while Euro-eta is 96.60%.
Could anyone put some more light on this, or my only option is the ask both manufactures to provide efficiency rating according to both standards, if they are willing to do so?
I know that inverter efficiency, aside from the type and quality of electronic components used, also depends on the DC voltage, inverter output power and ambient temperature as well, but I don't know how it is actually measured according to various standards.
So after doing some research, I determined that CEC efficiency is calculated as an average value of DC/AC conversion efficiency at six pre-defined outputs between 5 % and 100 % nominal power, while calculation of European-weighted efficiency is more fuzzy and seems to be somehow determined from several efficiencies at different operating points that are weighted according to the frequency with which they occur at a specific location somewhere in Europe.
Web sources which compare the above two methods/standards of calculating PV inverter efficiency and provide some sort of conversion seem to be non-existent, while some inverter manufacturers occasionally do give efficiencies according to both standards, where more often than not “European" efficiency is higher than the CEC one, for example CEC-weighted is efficiency of 97.5% is sometimes given as 98.1% European-weighted. However, examples where this is oposite also exists, for instance one partular make and model of the inverter has CEC efficiency of 97.00% while Euro-eta is 96.60%.
Could anyone put some more light on this, or my only option is the ask both manufactures to provide efficiency rating according to both standards, if they are willing to do so?