Creating an inverter configuration

You can find the button to access the inverter configurator at the following location:

At this stage, you can choose whether to create an Automatic or Manual configuration.

With a Manual configuration, you build the setup from scratch by adding each inverter individually.

With an Automatic configuration, you define the inverters available for the project, the desired DC ratio, and other project criteria. Based on this input, Virto.CAD will generate several configuration options, allowing you to select the one that best fits your design. From there, you can still make Manual adjustments as needed.

In the following sections, we will explain each process in more detail.

 

Creating groups

The first option in this window is to create groups of modules that require separate configurations. The process is the same for Automatic or Manual configurations.

The group option requires a few inputs:

• Group name
• Sub group by rows
• Sub group by East/West
• Layer color
• Max count of modules or KWP

Group name: This is the name that will be used for the layers and displayed on the project.

Sub group by rows: This option will automatically create a sub group for each row on the system. This way different rows with different shading levels can be put on separate MPPT's easily.

Sub group by East/West: This option will automatically create sub groups for East and West facing modules to make sure those can be set on separate MPPT's easily.

Layer color: Choose a color to represent this group and any associated subgroups.

Max count of modules/kWp: You can also establish a limit for the number of modules or racks to be included in this group, allowing you to specify either a total number of modules or a kilowatt peak (kWp) value. During the selection process, if you exceed the established limit, a notification will appear to alert you.

You can create as many different  groups as needed.

 

Manual Configuration

System configuration

After creating your wiring groups, you can manually define your preferred configuration. You can select each inverter and assign every Input, MPPT, or Inverter to the appropriate group. In this step, you will need to complete the following parameters:

• Select Module: In this section, you will specify the module that will be utilized for the group. Only the modules that have been added to the project will be available for selection.
• Transformers: Here, you will choose the appropriate transformer to be employed in the configuration. By default, only one transformer named Trafo is available. If you want to rename it, add additional transformers, or customize their physical dimensions (length, depth, thickness), you can do this in the Components feature.
• LV Cabinets: Select your preferred low voltage (LV) cabinet from the options available. By default, only one low voltage cabinet named LV is available. If you want to rename it, add additional Low Voltage cabinets, or customize their physical dimensions (length, depth, thickness), you can do this in the Components feature.
• Inverters: Select an inverter from the available database. You can include multiple inverter types in your configuration, but you must add them one at a time.
• Y-connectors: Turn this option on to use Y-connectors
• Combiner box: Select this option if your configuration includes the use of combiner boxes to optimize the wiring of your modules.

Specify how many Modules you want to connect per string by dragging the blue slider to the desired value.

After defining the modules per string, you can set the calculation temperature, review the maximum open‑circuit voltage (Max Voc), see the total number of modules that can be connected with this configuration, and check the resulting DC/AC ratio.

Finally, click the Add button to apply and create the configuration.

Once you have added the inverters, you can start assigning them to the appropriate wiring groups. If you are working with an east‑west configuration, you can alternate them at either the MPPT level or the inverter level using the Alternate button.

Additional options for editing, deleting, or reordering this configuration are explained at the end of this article in the Configuration tab section.

 

Automatic Configuration

System configuration

After creating your wiring groups it’s time to define the project criteria to generate automatic inverter configuration options. First, select the wiring groups to which this configuration will apply by checking the box beside each group. Under the group creation section, you will find:

Devices

Click the plus icon to add the Inverters you will use for this project. You can add multiple inverter types, but ensure they all share the same Output Voltage value to maintain compatibility. (Central Inverters are currently not supported)

Open the Module dropdown and select the module this configuration applies to. If your drawing contains multiple module types, all available options will be listed. If there is only one module type, it will be selected automatically.

Then select your Transformer. By default, only one transformer named Trafo is available. If you want to rename it, add additional transformers, or customize their physical dimensions (length, depth, thickness), you can do this in the Components feature.

Finally select your Low Voltage cabinet. By default, only one low voltage cabinet named LV is available. If you want to rename it, add additional Low Voltage cabinets, or customize their physical dimensions (length, depth, thickness), you can do this in the Components feature.

Project Criteria

In this section, you can specify the Temperature range at which you want to calculate the system. Then, you can define the target DC/AC ratio range. Drag the blue sliders to set the upper and lower limits.

Indicate whether you will be working with Y-connectors and, if needed, specify a Preferred String Length. To do this, move the slider to your desired value to define how many modules you want to connect per string.

Click the Generate button to finalize and create different Inverter Combinations. 

Beta Restrictions:

- Short-circuit current (Isc) must not exceed 80 A (no central inverter).
- String combiner boxes are not configured automatically (no central inverter).
- MPPT string inverters must not be unbalanced (field in Components database, imported from PVsyst).
- Fixed-voltage inverters are not supported (field in Components database, imported from PVsyst).

Inverter Combinations

Once the combinations are generated in this window, you can sort them by priority, choosing either the highest DC/AC ratio first or the highest preferred string length (Pref. SL %).

You will then see a list of possible combinations. Based on the inverters you selected, the list will show how many units of each inverter are required per combination. On the right side, you can review key information such as AC kW, DC/AC ratio, and Pref. SL %. After selecting your preferred option, click the Add button. The configuration you selected will then appear on the right side of the window under the Configuration tab.

 

Configuration Tab

In the Configuration tab, you can review and edit the selected setup, regardless of whether it was created using Automatic or Manual configuration. All types of edits can be made here, just as if you were working on a manual configuration.

For better visibility, use the Expand All and Collapse All options under the Configuration tab label to show or hide all configuration details.

To change the string length, click inside the numeric field of an Input String and enter the desired value. Note that when you change the value for one string, all strings within the same MPPT will automatically be updated to that value.

By right‑clicking on any device (Input, MPPT, Inverter, LV, or Transformer), you will access additional edit options, such as Deleting the selected device or creating an identical one with the Duplicate option.

From the same list of options, you can also change the order of inverters:

- Move to Top: sends the inverter to the first position

- Move to Bottom: sends it to the last position

- Move Up: moves it one position higher

- Move Down: moves it one position lower

 

Overview Tab

By selecting the Overview tab for both Automatic and Manual configurations, you will see a detailed matrix listing each inverter vertically and each input horizontally, showing the exact number of modules or string length for every combination. This provides a clearer view of how the MPPTs are distributed across the inverters. You can export this data to Excel using the Export .xlsx button at the top and then modify or adapt it as needed for your reports.

 

On the bottom right there are 3 buttons available:

• Insert device
• Insert SLD
• Refresh

Insert device

Using the Insert Device feature, you can seamlessly add all listed devices to your project. Please note that while the placement of transformers and LV cabinets requires manual positioning, the remaining devices can be inserted automatically for your convenience.

The automatic options are:

• Along tray: Manually select the tray or trench next to which the devices need to be placed.
• Automatic: The system will place the devices based on of two options.
  • Polarity: places the devices in the field close to the strings linked to that device
  • trench/tray: places the devices next to a predefined trench or tray on your drawing while still remaining as close as possible to the right strings.

 

Insert SLD

With this option you can insert a single line diagram on your project.

 

Refresh

The refresh button will refresh the configuration in the case it didn't automatically update.