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How to set the right Power Factor setting?


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in Germany we have (mostly) to set the cos(phi)=0.9.

The SMA 25000TL "outout parameters" are tan(phi)=-9.95 to +9.95, so I can choose a cos(phi) from 0.1 to 1, right?

Nominal AC Power defined as

-active power [kW]

Should in not be set to "Apparent power [kVA]" be default? The SMA 25000 TL datasheet says 25,000 kVA.

Miscellaneous tools: Power facor:

Again, [kVA] or [kW] for the "Nominal maximum power defined as"

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Some SMA inverters have indeed a very large Power factor range.

SMA claims that you can even specify Cos(Phi) = 0 (means that the inverter produces reactive energy during the night) but this doesn't make sense for the results of the diurnal simulation. This is the reason why we limited the Cos(Phi) to +/- 0.1.

For the parameters in the PVsyst database, they have been specified by SMA people. Please ask them.

However you are right: suppose you have a cos(Phi) of 0.1, the apparent power at Pnom = 25 kW (effective) would be 250 kVA, which means a quite irrealistic current !

The PNom limitation is usually corresponding to an output current limitattion, and should indeed be expressed in kVA.

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  • 1 month later...
  • 1 year later...

Hello, me again...

The new Huawei SUN2000-42 kTL can be set to 42 kW and 47 kVA -> 42 kW plus 5 kVA -> cos phi = 0.9

Should I set in the OND file:

Nominal AC power = 42 kW

Maxium AC Power = 47 kW (this should be kVA)

If I switch "output parameters -> Nominal AC power defined as" from kVA to kW the units under "Main parameters" are switching too. This is a bit confusing to me.

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  • 2 weeks later...

In this case you should specify PNom = 42 kW (in terms of energy).

The Pnom = 47 kVA will be the power attained with a cos(Phi) of 0.9. However this cos(Phi) is not a basic parameter of the inverter, it is an operating parameter (only the limits for Cos(Phi) are a specification of the inverter).

Therefore you cannot give a specification like (PnomApp[kVA]), as it will depend on the operating conditions.

If the manufacturer specifies a PNom value in terms of Apparent power [kVA], this corresponds indeed to an output current limit. In this case the PnomEff[kW] will range between 42 kW (cosPhi=0.9) to 47 kW(CosPhi=0)

NB: The PMax parameter in PVsyst in not related to the Power factor: it is a possible derate of the nominal Pnom value, when the temperature is sufficiently low.

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