String

It offers a visual interface that users can generate strings automatically, draw string routes on the roof layout, monitor electrical values in real time, and validate system compatibility.

Purpose of This Page

The main purpose of this page is to define how solar panels are electrically connected within the system. Proper string configuration is critical for maintaining voltage and current values within the operational limits of the inverter. By ensuring correct configurations, you can maximize system efficiency, prevent potential electrical issues, and guarantee safe and reliable operation over time.

This page also acts as a validation layer, helping you identify configuration mistakes early in the design process before installation.

What You Can Do Here

On the String page, you can perform several key actions:

• Generate a complete stringing plan automatically from the panel layout and the inverter limits with Automatic Stringing

• Create electrical strings by selecting and connecting panels directly on the roof layout

• Assign each string to a specific MPPT input, allowing better control over energy optimization and inverter performance

• Visually map string routing, making it easier to understand how panels are grouped and connected

• Monitor critical electrical parameters, including open-circuit voltage (Voc), maximum power voltage (Vmpp), and current values

• Receive real-time validation feedback, with warnings for any configuration that exceeds inverter limits or design constraints

• Modify existing strings by adding or removing panels as needed

• Distribute strings across multiple MPPTs to balance loads and improve system efficiency

• Clear the whole stringing plan in one action and start again

Interface Components

Left Panel: PV System Menu

• Navigate between PV Panel, Setback, Inverter, and String

• Remains visible without losing the current configuration

Center Area: Roof Layout

• Displays the roof layout on a satellite map

• Shows all placed panels and roof dimensions

• Main workspace for drawing strings

While working:

• Strings appear in distinct colors

• Routing lines connect panels

• Connection nodes appear in drawing mode

Right Panel: Inverter and MPPT Management

• Displays inverter specifications (MPPT count, AC power, max DC power, and current)

For each MPPT:

• View assigned strings

• Track total values

• See validation status

How It Works

Stringing can be done using two different methods, selected from the tabs on the right side of the screen.

Automatic Stringing

The Automatic Stringing option at the top of the String panel generates a complete stringing plan in one click, using the panel layout and the inverter's electrical limits.

Click Run Auto String to generate the plan:

• Strings are named automatically (A, B, C…), color-coded on the layout, and assigned to specific MPPTs

• The plan respects the worst-case electrical series limits (minimum and maximum panels per string) and the MPPT current limits

• Each string stays within one panel table and one orientation group, and gets a routed cable length

• Existing inverters and MPPTs are preserved; only the strings are replaced

Running Automatic Stringing replaces all current strings. The previous stringing is kept as a single undo step, so one Undo restores it. Generated strings can afterwards be edited, reassigned, or removed with the normal manual tools.

When the run finishes, a summary shows how many strings were generated, how many panels could not be strung (if any), and a list of warnings.

Full Auto and Guided Modes

Open the settings on the card to choose the Mode:

• Full Auto (default)

  Series limits come from the worst-case electrical calculation, and the system decides everything else automatically.

• Guided

  Lets you set custom rules for the run:

  • String length (min–max panels): Minimum and maximum series panels per inverter model. A side left blank keeps the electrically calculated limit; values outside the worst-case range still run but return a warning.

  • Parallel strings: Allow multiple equal-length strings on the same MPPT, bounded by the MPPT current limit.

  • Cross-facade strings: Allow strings to span roof faces with a compatible orientation. Opposite orientations, such as east- and west-facing panels, are never mixed.

Automatic Stringing needs at least one inverter with configured MPPTs and placed panels. The result is deterministic: the same design with the same settings always produces the same plan.

Manual Stringing

String creation begins by selecting an MPPT input from the right panel and clicking the "+" button next to it. This activates drawing mode, prompting the user to click panels or drag across multiple panels on the roof canvas to build the string. Each panel added to the path becomes part of the same electrical string.

As panels are selected, the system continuously calculates electrical parameters based on the panel specifications and the inverter model:

• Voc, Vmpp, and Isc values update in real time

• Routed cable length and total panel count are shown instantly

• The allowed panel range for the current string is displayed at the bottom of the screen, representing the worst-case scenario for the project area. Connecting strings beyond the operating limits is allowed but not recommended.

Once a string meets all requirements, a validation summary appears confirming that voltage and current values fall within the inverter's operating limits.

• Strings that pass all checks are marked with a green indicator.

• If any limit is exceeded, a red warning is shown on the MPPT row. Users may still proceed because production calculations will use the maximum values within the valid limit range. Since operational limits represent worst-case thresholds, connecting additional panels beyond these limits remains a user option.

Multiple strings can be created and assigned to different MPPTs. Each string is color-coded on the layout.

String Creation Process (Step by Step)

Step 1: Select an MPPT Input

Open the right panel and locate the inverter's MPPT inputs. Click the "+" button next to the MPPT you want to assign the string to. This creates a new string entry and activates drawing mode. A prompt appears at the bottom of the screen indicating that panels can now be selected on the canvas.

Step 2: Draw the String on the Roof

Click on individual panels on the roof to add them to the string one by one or drag across multiple panels. As each panel is added:

• A routing line connects them in sequence

• Electrical values in the right panel update instantly

• The panel count and estimated cable length are shown alongside the current voltage range

Once all desired panels are selected, press Enter or Esc to save the string.

For C&I projects, panels can also be selected first and then assigned to a string. In this case, the selected panel group is automatically ordered to minimize cable routing distance.

Step 3: Monitor Real-Time Validation

As the string grows, the system continuously checks whether the configuration is valid:

• The MPPT row displays the current Isc value

• Red warnings flag any limit violations

• The allowed panel count range is shown at the bottom of the screen as a reference

Step 4: Complete and Confirm the String

Once the desired panels are selected and all values are within limits, the string is finalized. A validation summary appears showing:

• Voc and Vmpp values for minimum and maximum temperature conditions in the project area

• Isc value confirmed against inverter limits

• A green ‘All checks passed’ confirmation appears when the string is fully valid, while a red signal indicates ‘Needs correction’.

Step 5: Add More Strings if Needed

Repeat the process for additional strings by clicking the "+" on the same or a different MPPT input. Adding multiple strings to the same MPPT creates parallel strings:

• Each new string is color-coded differently on the roof layout

• The first current value shown next to an MPPT represents the total combined current of all parallel strings connected to it; the value on the right is the MPPT's current limit. If the total exceeds this limit, a warning is displayed on the MPPT row.

• Continue until all panels are assigned and the full system configuration is complete

Clear Strings removes the whole stringing plan at once, which is quicker than deleting strings one by one when you want to start again or rerun Automatic Stringing from a clean layout. Clearing removes every string and its MPPT assignments. Inverters and MPPTs themselves stay in place.

Key Outputs

• Electrical validation result per string with pass or warning status

• Voc, Vmpp, and Isc values under minimum and maximum temperature conditions

• Panel count and routed cable length per string

• MPPT-level current totals and string distribution

• Color-coded visual representation of all strings on the roof layout

• Real-time system compatibility feedback throughout the configuration process

• Stringing losses, including losses caused by panels with different radiation exposure within the same string, or by connecting more or fewer panels than the optimal range, are calculated and presented in the loss chart within the proposal

Important Note: Stringing is optional. Any panel not assigned to a string operates independently at its maximum power point as if an optimizer were present, and contributes no stringing loss.

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Related Pages

• Panel Placement & Inverter Selection Page

If you encounter any issues, feel free to contact us.