Inconsistent Inverter Performance with Uneven strings DC Blocks

[Marcos]

I'm currently simulating a 200 MWdc solar farm using PVsyst, and I have a layout consisting of 27 DC blocks. These blocks have an uneven distribution of strings, which is not optimal, but it's the reality of the project.

I've run two different simulations:

1. One with a single subarray representing the total amount of strings needed to achieve 200 MWdc.
2. Another with 27 individual subarrays, each reflecting the actual amount of strings per DC block.

Both simulations have the same total number of strings, but when I run the simulations, the overall performance results are almost identical, which seems incorrect. I would expect some inverters to perform better than others due to varying DC/AC ratios across the uneven blocks.

How can I accurately model the performance differences between these DC blocks and inverters in PVsyst? Specifically, how can I reflect the real impact of the DC/AC ratios on individual inverter performance?

Any insights on how to resolve this or if I am missing something in the modeling process would be greatly appreciated.

Thanks!

[André Mermoud]

No problem. This is quite well addressed by the PVsyst simulation. You don't mention the order of magnitude of  the discrepancies between your blocks, but when the DC:AC ratios are not too high, the overload losses are only slightly dependent on the PV nominal power.

You can simply try to simulate a simple system, with your different blocks independently, for the evaluation of the overload loss in each case.