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Electrical devices
We start by opening the Electrical devices menu.
Before proceeding further, we must select our PV area’s boundary line and press Space or Enter on the keyboard.
We can see that having done so, we are now presented with the total available and used string amount.
Our next step will be to define the type of electrical system we will be using. By clicking on the drop-down menu, we are presented with seven system types:
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String inverter - Transformer;
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String inverter - AC combiner - Transformer;
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DC Combiner - Central Inverter;
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DC Combiner - Inverter - Transformer;
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DC Harness - DC Combiner - Central Inverter;
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DC Harness - Inverter - Transformer;
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DC Harness - IPC - Central Inverter;
For our example, we will utilize the String Inverter and Transformer option.
Our next step is to define the number of strings per inverter and the number of inverters per transformer.
As we can see, the software takes the string count and inverter count and provides us with the number of strings per transformer and the calculated number of inverters and transformers for our system, as well as the number of leftover strings.
To finalize the configuration, we need to define the AC Power - the power in kW of the inverter. Once we attach the strings to the inverter, we should see the DC/AC ratio on the Electrical Overview.
It should be noted that the number of devices per transformer or Central inverter you specify will be the hard limit. This will prevent unused strings from being assigned to electrical devices should you reach the string limit for the devices.
We also have the option to choose the device placement type from either of the four options:
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Trench adjacent - devices are placed next to the alignment line. The alignment line is defined by the user;
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Row clustering - devices are distributed in the selected rows and placed as close as possible to the alignment line;
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String adjacent - places electrical devices at the end of the frame which ends this particular device's connection and as close as possible to the alignment line;
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Centralized - place all the DC/AC combiners and string inverters together in a centralized location.
In our example, we will use the Trench Adjacent device placement. With Trench adjacent placement, devices are placed next to the alignment line. The alignment line is defined by the user;
Firstly, we must draw the electrical device alignment line. All subsequently placed electrical devices will be placed as close as possible to the alignment line. We draw an alignment line by typing PLINE and placing it where we want our devices to cluster towards. We place the start point and then the endpoint of the alignment line and press Space or Enter on the keyboard.
Having established our device alignment line, we must now define our transformer station objects and their positions. In this case, we will use the RECTANG function and draw a rectangle that will serve as a transformer station object. The rectangle must be converted to a Block Reference object for it to serve its purpose. This can be done by typing BLOCK and pressing Space or Enter on the keyboard which will open the Block Definition menu. There we assign the name, to our rectangle, and using the Select objects button, we select the rectangle. After that, we click OK and our rectangle was transformed into a Block reference which can now be used as a transformer.
Note: you may also make copies of this object and place them into the drawing as necessary.
Having established our alignment line and our transformer, we now have everything necessary to start our electrical device placement.
There are two ways of placing electrical devices in PVcase:
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Automatic generation - the software will place the devices according to the orders defined in the Device numbering and String numbering sections.
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Semi-auto generation - the user has finer control over how the software assigns strings and frames to string inverters, DC combiner boxes, or DC harnesses. This mode gives full control over specific strings and the way they are numbered in a sub-device. Devices and strings will be numbered in the order in which they were selected (For example, the first device you select will be labeled as number 1).
We will start with the Automatic generation mode. Once we start the Auto-generate feature, we will be prompted to select a transformer. Once we click on the transformer block object, we press Space or Enter on the keyboard. Then we are prompted to select the alignment line for the device placement - just like before, we select the line and press Space or Enter on the keyboard. We are now able to select the strings we want to use for this transformer.
As can be seen in our example, we have partially-filled inverters. In Auto Generate mode, PVcase will only connect fully populated inverters - any unused strings will be left out of the generation.
Note: the above example will only place 17 Inverters, leaving excess strings unused.
Once we have selected our strings, we press Space or Enter on the keyboard.
As the image below showcases, the software has placed the devices next to the alignment line. In the case that some strings were not assigned to an inverter and transformer, they can be resolved by using Semi-Auto generation.
We select the Semi-Auto generate function from the drop-down menu and the procedure is similar to automatic generation:
We are prompted to select our transformer - just like before, we select the rectangle and press Space or Enter on the keyboard. Similarly, for the alignment line - we select the line and press Space or Enter on the keyboard. We are now able to select the remaining strings we want to use for this transformer.
Once we have selected our strings, we press Space or Enter on the keyboard.
Now we will be presented with a pop-up asking if we want to string these inverters with values differing from our initial configuration.
If we click “No”, the string will not be connected; If we choose “Yes” only this inverter will be connected with an alternate string count and if we click on “Yes to all” then the Electrical device preset will be updated. In our case, we want to choose“ Yes”.
Just like before, the software has placed our inverter next to the alignment line.
In addition to the above, we can enter the Numbering and Labeling menus to modify how the string numbers and names are assigned.
Electrical device placement algorithm notes
The automatic generation algorithm works well for the most part but can produce these impractical situations in which a combination of auto and semi-auto generation must be used.
1. Frames are connected far from each other
In some cases, the auto-generation algorithm finds missing strings for another connection quite far apart:
In this case, you can use the semi-auto generation to reconfigure connections:
2. Using auto-generate in parts
If you prefer to leave uneven connections on the opposite side of an area or only connect a part of an area using auto-generate, you can do this in two parts.
The first step is to use auto-generated on evenly connected frames on one side( 1 ). Then the second step is to select the rest of the strings in a separate generation ( 2 ).
Then the final output looks like this ( 3 ).
3. Mixing auto and semi-auto generations
We would usually recommend using a combination of both these generation types. Typically, the automatic generation algorithm works fine for a larger part of your fixed-tilt area. When some changes need to be made for trickier areas - that's where semi-auto generation comes in.
For instance, in the example situation below, there are two areas that connect inverters to one transformer.
The two segments with blue outlines spanning both areas can be generated using the auto-generate algorithm.
A step-by-step process of that can be seen in the GIF below.
Afterward, semi-auto generate can be used on the rest of the upper PV area.
Important: You can only connect automatically strings together that are within the same PV area. You can join strings between areas using semi-automatic generation only.
Having placed devices for both areas, there's just one thing left to do - fix the numbering. Doing the generation in parts results in placing devices which in turn impacts the numbering. This means situations like this appear:
To fix this we have the Renumber feature which allows us to set a starting number for a device and then select devices either one by one to define the order or use a multi-select for default numbering.
Overview
We also have the Overview menu, which allows us to view the entire device chain in an expandable tree menu, where we can view each electrical device in greater detail, with the ability to toggle on and off devices and seethe DC/AC ratio, voltage drop and cable cross section (after cable generation).
It is also possible to right-click on each device, to Locate objects, Edit number, Add strings, Export SLD for this device, Select cables (after the cabling design), Change parent device, Change AC power Delete devices and copy a pattern.
1.Match system - matches the selected system type and configuration inputs that were used for a particular transformer or central inverter.
2. Locate object - locates a specific device or string inside a drawing. Simply right-click on the component in the overview tab and click locate object or double-click.
3. Hide objects - the ability to hide objects so that you can better track progress, identify easily which parts belong to which device, and of course vastly improve the performance on large-scale sites by hiding parts that are already finished.
4. Renumbering - you can use the overview tab to change the numbering of transformers, central inverters, and other devices.
🛈 To save some space on the screen - you can use the Undock button and place the overview tab wherever you prefer.
5. If there is a necessity to move a device to a different Transformer/Central inverter, the Change parent device function can be used. Example below:
6. Add string allows the user to add strings to a connected box, as can be seen below:
7. In the overview menu, after the strings are assigned to a specific device, you can see the DC/AC ratio which is calculated automatically according to DC and AC power per device.
The AC power can be changed if necessary even after the devices were placed. By using the Change AC power function. Example below:
8. Export SLD for this device allows exporting a reduced SLD for a specific component. In the Overview menu, right-click on a device to generate the SLD for that device only.
9. Copy - Paste of strings and electrical devices
If you have optimized your strings, inverters and transformer placement and would like to replicate the same pattern in other parts of your drawing, you can use this function.
After copying a configuration, just use Ctrl+V or Paste to replicate it in the desired place:
Limitations:
- Strings connecting different frames might not work.
- Frames that are not 100% strung will not work.
- The positioning of the frames can vary slightly. The pasted string has to touch the frame to be adapted to it.
Instead of using these options from the Overview, most of them can also be used by right-clicking on the device (transformer, combiner, inverter, string) in the drawing and then selecting PVcase: