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Huawei Optimizers 1string/mppt limit

R. Polášek

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In the most recent version of PVsyst 7.4, the use of Huawei optimizers mandates only connecting a single string to each mppt. This should be correct only for the new model of Huawei optimizers (MERC 1100 and 1300W). The older optimizers (450 and 600W-P) should not have this limitation as they can be (as is explicitly stated in the manufacturer's user manuals) connected to a single MPPT in paralel, meaning two strings with partial or full set of optimizers can be connected to a single mppt (bearing in mind the other important rules that the manufacturer states). I have also tested this the older version of PVsyst (7.3) and the limitation for single string/mppt was correctly not present in that version, only in 7.4.

I would like to ask that this problem is looked at and if possible corrected for the SUN2000-450W-P and SUN2000-600W-P optimizers. And if possible, if the newer version of 450W optimizers (P2 instead of P) could be also added to the Huawei optimizer database.

Thank you in advance.

R. P.

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Yes indeed, we are aware of this problem.

For the version 7.4.3, we have implemented the new complex rules specified by Huawei, for the implementation and use of their optimizers.

For doing this, Huawei provided 2 very different protocols, for low power (450 and 600W) and high power(1100 – 1300 W) optimizers.

The protocol for high powers specifies that you can only connect one string per MPPT. What we did and is on the basis of our new implementation.

We thought that this statement was also valid for the low power optimizers, and we developed this complex tool with this hypothesis.

But it appears that this is not the case.

The only way of using your 450 W with several strings per MPPT is to revert to the previous version 7.4.2.


However the versions 7.4.2 is not compatible with the patchs 7.4.3 (or 7.4.4, 7.4.5):  you cannot use them in parallel, you will have to uninstall the V 7.4.3.

If you really need  to keep parallel versions, you can install the version 7.3.4, which may be installed/used in parallel with the versions 7.4.3.

This will be corrected in a version 7.4.6, to be released in January 2024.

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