Mix of modules on same inverter

[julmou]

Good morning,

I was reading this section of the Help: Project Design > Grid-connected system definition > Sub-arrays and the part about which all the strings of modules connected to an inverter are homogeneous (identical modules) -> see screenshot below

I was trying to recreate a former project of ours: Bungala Solar Farm in South Australia, actually one of the best performing PV plants in the country. And it involves a mix a two types of modules:

JINKO SOLAR 325 Wp PV MODULE (JKM325PP-72-J4V)

JINKO SOLAR 330 Wp PV MODULE (JKM330PP-72-J4V)

See datasheet below

Each inverter (Sunny Central 2500-EV) hosts 259 strings of 30 modules, of which 78 strings with 325 Wp and 181 strings with 330 Wp.

See screenshot below for a detailed layout of a 5 MVA block: in green the 325 Wp modules, in yellow the 330 Wp modules

It bothers me that we cannot simulate such a notorious PV plant on PVsyst. It is surely not advised to mix different module models on the same inverter input, but these two types are closely related and have fairly similar specifications.

Moreover, the real issue is that with such huge projects, it can be very difficult to secure from the manufacturer the amount of modules needed for the entire project in one model. Bungala Solar Farm 1 contains 420,000 modules (and just as many for Bungala Solar Farm 2) -> there is sometimes no choice but to accept a deal with the manufacturer and have a mix of two types of modules for the project. In such a situation, it's a shame that we can't design the plant with a mix of modules in PVsyst.

Renewable projects in Australia are usually quite big and a few of them would be in the same situation, it would be attractive for customers if this mix of modules could be taken into account by the software.

Is there any chance of an upgrade in the future?

Julien

[jammyc]

Might this be one for the Suggestions section?

I agree it would be handy for modelling historic parks. Of course, if you know the specific arrangement and depending on what it is you are doing you might be able to recreate an equivalent module for that project, as seen by the inverter.

[dtarin]

Create an inverter with dummy MPPTs and allocate strings accordingly for each module type to one shared inverter. It looks like there you have two inverters which have two types of modules connected to it, but hard to read the small print in the screenshot. 

[André Mermoud]

Yes indeed, this problematics is often asked to the PVsyst team.  We consider providing a solution in the future, but probably not before several months.

In the mean time: the solutions mentioned above may be acceptable workarounds.

We can observe that the difference in power between both module kinds (325-330Wp) is 1.5%.

If  the expected result is only the system yield, you can perform 2 simulations, one with each module, and do a weighted average of the E_Grid. With this approximation, except the energies (EArray and E_Grid), all the losse (in percentage) will be quasi-identical in both simulations.