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Sub-arrays

In grid-connected projects, the "system" is defined as the set of components constituting the PV array—that is, the PV modules, strings, inverter, and grid connection.

The system is organized as a set of sub-arrays: one sub-array consists of:

  • A PV module model, chosen from the database,
  • An inverter model, chosen from the database,
  • The number of inverter inputs (either full inverters or number of MPPT inputs; see Multi-MPPT inverters),
  • The number of modules in series and the number of module strings.
    • The number of strings should ideally be a multiple of the number of MPPT inputs. However, PVsyst accepts uneven numbers of strings and distributes them in the most balanced way across MPPT inputs—for example, 10 strings on 3 MPPT inputs will be distributed as 3 + 3 + 4. A warning is issued when the imbalance is excessive (for example, distribution of 2 and 3 strings on different MPPT inputs).
  • In some cases, additional devices may be added to the sub-array: for example Module or String Optimizers.

As a consequence of this organization, in PVsyst all the strings of modules connected to the input of an inverter (or a MPPT input), are homogeneous: identical modules and inverters, same number of modules in series, same orientation.

However some aspects of this homogeneity are a general rule for any real installation: you should never put a different number of modules in series on a same inverter input: this may have dramatic consequences on the operating conditions of your system (namely for the MPP research).

And mixing different module models on a MPPT input is not advised. Studying arrays with different module kinds (for example a mix of power classes) is not possible in PVsyst in the present time.

Orientation

Each sub-array is associated with an orientation. Normally, all modules in a sub-array should be in the same orientation.

Mixing PV modules of different orientations within a given string is unacceptable, as you may experience significant mismatch current losses due to different irradiances (string current is limited by the weakest cell).

However, you can mix strings in different orientations because voltage mismatch (strings in parallel) is typically very low. PVsyst allows the creation of sub-arrays with 2 orientations on the same inverter input (see Mixed orientations planes).

Managing sub-arrays

PVsyst allows you to define an unlimited number of different sub-arrays.

You can manage them (add, copy, rename, move, and delete) from the list on the right of the dialog.

For managing or automatically sizing each sub-array, you can specify either the desired nominal power or the available area for your modules.

Simulation

During the simulation, each sub-array is modeled independently, but only the energy and loss totals are available as outputs. If you want to study the losses of a specific sub-array, you should run a simulation of that sub-system alone.