<< Click to Display Table of Contents >> Navigation:  Project design > Grid-connected system definition > Sub-arrays

In Grid-connected projects, the "system" is defined as the set of components constituting the PV-array, i.e. the PV modules, strings, inverter, up to the connection to the grid.

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

The number of strings should ideally be a multiple of the number of MPPT inputs. However PVsyst will accept uneven number of strings, and will distribute them in the most balanced way across the MPPT inputs - for example 10 strings on 3 MPPT inputs will be distributed as 3 + 3 + 4.  A warning will be issued when the imbalance is too high (for example distribution of 2 and 3 strings on different MPPT inputs).

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

An orientation is associated to each sub-array. Normally all modules of a sub-array should be in the same orientation.

Mixing PV modules of different orientations within a given string is not acceptable, as you may have big mismatch current losses due to different irradiances (the current of a string is governed by the worst cell).

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

Managing sub-arrays

PVsyst allows the definition an unlimited number of different sub-arrays.

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

For the management or the automatic sizing of 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 will be modeled independently, but only the energy and losses sums will be available as outputs. If you want to study the losses of a specific sub-array you should perform a simulation of this sub-system alone.