Different capacity of modules on same Inverter & degradation factor for mixup of old and new modules

[Abhijeet Mhaisne]

Dear Sir,

Query 1

I am trying to do simulation as details given below :

1. Inverter - 500 kW (ABB, Model : PVS800-57-0500kW-A),

2. Thin Film Modules of 62.5 Wp, 65 Wp, 67.5 Wp, 70 Wp of Abound Solar

There are blocks of inverters having different capacities of modules as for Ex. Block 1 : 65 67.5 & 70 Wp modules (3 Capacities) are used on same inverter. I am not getting the way to do the PV syst to get the simulation.

kindly help me to do the same.

Query 2

It is existing plant of 5 MW capacity with 10 inverters of ABB & Modules as given above. Additional 500 kWp capacity is added in the the plant, on each inverter, 50 kWp capacity modules are added after 3 year running of the existing plant & module.. In that case the degradation of 3 year old modules is as per manufacturers recommendation. but how the combination of new addition & 3 years old modules are to be taken . I am confused, please help.

Please come up with best best suitable conclusions for both the queries at the earliest.

[André Mermoud]

In PVsyst, a sub-array concerns one (or several) MPPT inputs.

Each sub-array is supposed to be "homogeneous", i.e. same PV module, same number of modules in each string.

Therefore you cannot simulate these situations in detail and rigorously with PVsyst.

For the mix of different modules, you can eventually define an "average" module with the STC characteristics (Pmpp) corresponding to a weighted average of your modules distributions.

Or you can also redefine your inverters as several "dummy" Multi-MPPT inverters, to be attributed to different sub-arrays with different kinds of modules.

If you have 10 inverters, you can simply define different sub-arrays, each with an "homogeneous" set of modules.

NB: mixing strings of not too different modules in parallel should not induce significant mismatch losses. The mismatch loss in voltage (parallel strings) is usually very low.