Dimensioning(construction)

Owned by Iris Reichenbach
Last updated: Dez. 10, 2020 by Artur Sartison
3 min read

Wiring

To define the connection of modules and inverters, the following possibilities are available:


  • Calculate possible connections and then select one of these connections from the list

or

  • create/edit an interconnection completely by yourself.


In order to define an interconnection, there must exist data to the module-fields and inverters. Therefore it is useful to process the single points of the navigation bar chronologically.

If data for the design is missing, appropriate notes are displayed:

  • You have not yet created any module fields
  • You have not selected any inverters yet
  • You have created module fields, but have not yet set the number of modules

On the basis of the collected data, an attempt can be made to calculate possible interconnections. If no automatic wiring can be calculated, the message "No valid wiring exists for this module field" is displayed. In this case there is no suitable inverter in the list or the connection must be created manually. Sometimes the program does not find calculated connections. Possible reasons are:

  • The inverters in the list are over- or undersized; best is to empty the inverterlist, filter again using the power in an interval around the nominal power of the installation and add more inverters.
  • The count of modules does not fit: The modules of each modulefield are divided into strings of possibly variable length, so that the string voltages do not exceed the maximum mpp- and system voltage of the inverter. The common maximum system voltage of 1000V is partly already increased to 1500V, but normally the system voltage must not exceed 1000V. The number of strings which can be connected to an inverter is limited by the maximum input current of the inverter. Furthermore the strings which are connected to a MPP tracker must have the same length. That means, if an inverter has only one MPP-tracker, then the modules connected to it must be m strings à n modules. That means, the count of modules N has to satisfy N = m x n, where m and n are limited by the minimal and maximal voltages / currents of the inverter.
  • Certain types of modules need certain inverters: thin-film modules need inverters with transformers. If there is no such in the list, then no connection can be found.
  • For the successful calculation of possible interconnections it is helpful to add more possible inverters to the selection (at 'inverter'). Often it is best to filter e.g. by power and then add all found inverters of the manufacturer using ">>". But of course a greater choice of inverters will extend the computing time. If there is not possible to find a design using the design-calculation or manually, but the list of selected inverters shall not be extended, the count of modules (or the module itself) needs to be changed. If it is a CAD-installation, this has to be done in CAD.

Current wiring

The wiring of the currently selected design is shown in a circuit diagram. The table contains an enumeration of the inverters used in the wiring, the total number of inverters and strings as well as DC/AC-ratio and test result of the system. If there is more than one inverter, the DC/AC ratio of the installation is the average DC/AC ratio of the inverters. The results of the wiring check of the installation are listed in detail below. More details can be seen in the "Edit"-tab when an inverter, MPP-tracker or string is clicked.

Selection of the interconnection

If "PV-Simulation" successfully calculates interconnections, they will be shown in this list. When selecting an entry, the circuit diagram is displayed for selection. In order for the selected wiring to be accepted as the current wiring of the project, this must be confirmed with the "Accept" button. The new selection is then displayed under "Current wiring". Extensive electrical checks must be performed for each wiring. When calculating the wiring list, these are automatically processed in the background. The results of the check for the current wiring are displayed at the bottom of the page and under "Edit".

Circuit diagram

A circuit diagram is displayed for the current wiring as well as for all wirings in the selection list, which is also output in the project report. The circuit diagram for the proposals from the list is automatically displayed when the entry in the list is selected. If you want to switch to the circuit diagram of the current wiring, you have to select the current wiring by clicking with the mouse on the entry.