Large Discrepancy in Total AC Power After Simulation

[Jherche]

Hi,

I'm modeling quite a large project where there are 18x SolarEdge SE100KUS inverters, all using C651U optimizers. I've modeled a total of 54 total units (33.33 kW each). The Global system summary accurately calculates 1800 kWac. However, after running the simulation, there is a very large discrepancy where total ac power comes out to 1699 kWac. How can this discrepancy be fixed? Thanks!

 

Edited February 5 by Jherche

[Robin Vincent]

There is a known issue where the total AC power in the report is not accurate with SolarEdge subarrays.

This is due to the way the total is computed in the report, based on individual MPPT powers.

 

With SolarEdge and its specific way to attribute (and distribute) strings to inverters, the computation is sometimes incorrect.

 

This issue is on our roadmap, but as it does not impact the simulation results, it has been scheduled for a later version.

[PranavK]

Hello @Robin Vincent, 

I had a quick question related to a similar scenario.

The system I’m working on has a target AC capacity of 900 kW. In PVsyst, I’ve modeled this using 27 units of 33.3 kW (SE100KUS equivalent), which corresponds to 9 inverters. However, PVsyst reflects the total AC capacity as 899 kW (27 × 33.3 = 899.1 kW, rounded).

I wanted to clarify the following:

1. Does PVsyst internally use 899 kWAC or 900 kWAC for generation calculations in this case?
2. What would be the best way to model the system so that the AC capacity reflects exactly 900 kWAC instead of 899 kWAC?

Appreciate your guidance on this.

Thanks!

 

[Robin Vincent]

PVsyst will use the value specified as the inverter AC power, in this case 33.3kW.

If a difference of 0.1% on the total AC power is a problem, you could copy the inverter, change the max AC power to 33.4kW, and replace 1/3 of your inverters with this new one.

As long as the inverter name is unchanged, it will be usable with the same optimizers.