Losses due to Inverter Clipping , Power from Array is bigger then Inverter (AC/DC Ratio)

[Rizky N]

I have 42MW array PV however i only have 30MW Inverters, which means Solar Farm generated more Energy than my Inverter can handled (Inverter Clipping)

In Diagram Loss from Pvsyst only shown -0.3% "Inverter Loss over Nominal INV.Power" , however from my yearly-monthly-daily calculation the loss from this "Inverter Clipping" can cause from 5%-11% depend on how much irradiance which happen at that day.

I wonder whether the "Inverter loss over nominal INV Power" is the same as the losses of "Inverter Clipping", since the number of % is mismatch.

and whether PVsyst can forecast the losses due to AC/DC ratio or Inverter Clipping in order to us to get suitable PR Performance ?

[dtarin]

Inverter loss over nominal power is the same as inverter clipping. PVsyst handles clipping losses appropriately in my experience. It is difficult to say what is occurring without knowing some other details like which inverter or where the project is located (temperature, yearly GHI, etc). A 1.4 ratio seems a bit high to only have 0.3%, but it will be dependent on system type (ground mount, tracker, rooftop, etc.), equipment, and location. 

[André Mermoud]

I don't see how you can use the yearly-monthly-daily calculation for the evaluation of the overlaod loss. 

Only the houly values give the opportunity of evaluating this, this is what is performed by the simulation of PVsyst.

Now this is even not quite correct: for a quite accurate evaluation of the overload losses, the calculation should take the sub-hourly data (minutes data) into account. We are preparing such a possibility for a next version of PVsyst (but not available until some few months). .

 

[Rizky N]

On 5/25/2022 at 8:58 PM, André Mermoud said:

I don't see how you can use the yearly-monthly-daily calculation for the evaluation of the overlaod loss. 

Only the houly values give the opportunity of evaluating this, this is what is performed by the simulation of PVsyst.

Now this is even not quite correct: for a quite accurate evaluation of the overload losses, the calculation should take the sub-hourly data (minutes data) into account. We are preparing such a possibility for a next version of PVsyst (but not available until some few months). .

 

im using simple method to know the loss due to the Inverter Clipping from Daily Scada.
input where :

a. Irradiance per 15 min

b. Energy Exported per 15 min

from there we can deduce based on DC/AC ratio what is the max irradiance we can get daily for example for 1.4 ratio we can used max 720 W/m2.

Simulated Power based on Irradiance (in this term lets put 1000 W/M2) , we can get 42.042 KW or 42MW

so if we put Irradiance Limit 720 , and compare what losses we can have daily losses due to this inverter clipping.

 

Whether this calculation approach is suitable to look into as for to calculate how much loss we got due to the inverter clipping ?

thats why im concern since from PVsyst loss diagram, i can only found 0.3% loss from "Inverter loss over nominal INV Power".

i see in other topic which have this kind of case , you quote as below :

 

 

This makes me more certain since "Annual Production probability is almost meet with the PVsyst simulation.

Maybe .. just maybe this "Inverter loss over nominal INV Power" is not as much predicted in PVsyst.

[furkann71]

How can I calculate inverter clipping losses with pvsyt?

In my calculations the losses are lower than they are.

Where am I making mistakes?

Could you help?

 

[Linda Thoren]

Hello,

The inverter clipping losses, the Inverter loss over nominal power, is to large extent due to the sizing and configuration of your system. 

If you have higher clipping losses than expected, it could be due to the the definition of the multi-MPPT inputs. Please read the following help pages on the subject:
https://www.pvsyst.com/help/powersharing.htm
https://www.pvsyst.com/help/multi-mppt_more-examples.htm

It could also be temperature derating, at high temperatures inverters often have a lower nominal power. You can see the temperature evaluation of the inverter in the Output parameters in the .OND file.