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CEC and EUR efficiencies


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I'm getting a far different efficiency profile when calculating with CEC (98.0%) and EUR (98.3).

In my understanding, CEC/EUR efficiencies are merely a way of standardizing inverters efficiency, as all they do is to weight the efficiencies at different load levels to represent different climates.

From PVsyst help:

"If we denote by "Eff50%" the efficiency at 50% of nominal power, the weighted average is defined as:

Euro Efficiency = 0.03 x Eff5% + 0.06 x Eff10% + 0.13 x Eff20% + 0.1 x Eff30% + 0.48 x Eff50% + 0.2 x Eff100%.

Now for climates of higher insolations like US south-west regions, the California Energy Commission (CEC) has proposed another weighting, which is now specified for some inverters used in the US.

CEC Efficiency = 0.04 x Eff10% + 0.05 x Eff20% + 0.12 x Eff30% + 0.21 x Eff50% + 0.53 x Eff75%. + 0.05 x Eff100%."

From this, I understand that ii shouldn't matter if I use EUR or CEC efficiency to build my profile, I should arrive in the same Eff10% / Eff20% / Eff30% and so on.

Is that correct?

If it is, any clue on why my profiles are so different?


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