Using different sized modules for expansion projects

[karaokemasta22]

I would like to know if there is a way to implement different module types in 1 plant. My project is to expand on an already built plant but currently that module model is no longer available. I have to use a larger powered module since that is what is available in the market. So there are 40 new strings that contain modules of size 265W instead of 255W. I know that the power output of the new modules will be reduced because the voltage levels will be maintained when I connect these strings in parallel to a DCB.

For example, there is 1 inverter with 5 DCBs. 1 DCB has a total of 32 inputs and 12 of these are made up of the 255W modules while the other 20 strings are made up of the 265W modules. I have already made sure that I am not violating any of the inverter voltage and current limitations.

In PVsyst, can I make the system so that I can combine lower power modules with higher power modules in the same inverter?

Thank you!

[dtarin]

If I am understanding correctly, the inverter must have the MPPT share feature, and you can distribute your power that way across multiple arrays. For example, if the inverter has 8 MPPT inputs, and you enable MPPT share with two arrays, each array will get N MPPT inputs (whichever is the appropriate split). In number of inverters, you will select N. The chint inverter shown has three mppt inputs, so if I have one inverter and two arrays, I have to distribute the three inputs between them, and then press adjust to balance. Looking at the attached image with 15 MPPT inputs, I am specifying that there are 5 physical inverters (5*3) for this array.

[karaokemasta22]

Hello thank you for your reply. So the inverter that I am trying to use does not have multiple MPPT capabilities, which is why I think it is impossible to implement in PVsyst. Is this correct?

[André Mermoud]

In PVsyst you cannot specify different modules in a sub-array.

Therefore you cannot define your systemwithout using Multi-MPPT.

Now you can also redefine your inverter as a (dummy) Multi-MPPT device, and define 2 different sub-arrays. In this case you should use the button "Adjust" for correclty sharing the nominal powers of each MPPT input.

[dtarin]

How accurate is this method - creating a dummy multi MPPT device? I have a PE inverter which is being spec'd with two different modules, but does not have the multi mppt capacity. How do you size the number of MPPT inputs when doing so, is it just arbitrary?

[dtarin]

Thank you for the reply, that was my guess for approaching the implementation (hadnt gotten to trying it out).

As for your comment on overproduction, I cant think of a way to test or benchmark this. Perhaps Andre or someone at PVsyst with a better understanding of what is happening could comment on this.