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Minimum number of strings > Maximum number of strings


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I Had a strange message when I configure this PV Plant:

624 x Solar Frontier SF160-S

6 x SMA STP 17000 (A: 12 strings @ 8 modules / B : 1 string @ 8 modules )

Location, Orientation and Tilt are not important for my question

The message is visible at the Design of the array > Number of modules and strings > Nbre de strings

" Impossible (Min = 80, Max = 78) "

But this is not logical

If I look at the message “The inverter power is slightly oversized” I would say that there is no problem, no?

For info: I’m using PVsyst Version 5.60

Thanks for your help,



Look at the array design: Number of strings

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  • 2 weeks later...

The first assessment in red is indeed strange. It should be a warning in orange.

The lower limit of 78 Strings corresponds to a PNom ratio (Parray/Pinv) = 1, which is a reasonable minimum. Usual Pnom ratios are of the order of 1.15 to 1.25 (see below).

The upper limit is not clear, probably the specified available area. I have to check in the program.

But the second warning “The inverter power is slightly oversized” is quite justified.

Please see

- the help "Project design > Grid-connected system definition > Inverter / Array sizing" (directly accessed by the little orange button right top of the box),

- our FAQ on this forum What is the basic concept of Inverter sizing ?,

- The tool "Show sizing" just next to your message.

Now for the use of special inverters of the SMA series "tripower", please see How to use the inverters with very different MPPT inputs (Tripower of SMA) ?.

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