Inverter sizing and stringing recommendations

Summary

OpenSolar’s design tool helps you optimize inverter sizing and stringing configurations with built-in recommendations and real-time validation. These suggestions are automatically calculated based on:

• Panel specifications

• Inverter specifications

• Minimum and maximum site temperatures

This functionality applies to both non-DC-optimized string inverters and microinverters, helping ensure your design complies with key electrical limits and performance parameters. You’ll see helpful recommendations and warnings at both the inverter level and the MPPT level.

What Does the Tool Check?

OpenSolar dynamically evaluates whether your string configuration and inverter selection meet critical performance requirements and hardware constraints. Specifically, it provides:

• Recommended stringing lengths (based on Voc, Vmp, and temperature-adjusted voltages)

• DC/AC ratio guidance for energy yield and system efficiency

• Voltage limit warnings (for Voc and Vmp)

• Real-time compatibility feedback via color-coded icons and pop-ups

Inverter-Level Recommendations

When viewing or selecting an inverter in your design:

• Click the inverter info icon to open a detailed pop-up.

• This includes:

  • Inverter specifications

  • DC/AC ratios

  • Site-specific temperature range

  • Design advice for string limits and configuration

You can adjust the minimum and maximum temperature values for the site in the Info > Site Details section. These values are essential, as voltage behavior changes significantly with temperature.

MPPT-Level Insights

For systems using string inverters with multiple MPPTs (Maximum Power Point Trackers):

• A dedicated MPPT pop-up appears for each MPPT input.

• It shows:

  • Number of strings connected

  • Voltage per string at temperature extremes

  • Warnings if voltage limits are exceeded

If an issue is detected, the blue info icon turns red. Hover over it to view the specific warning—such as exceeding Voc at low temperatures or Vmp at high temperatures.

What About Microinverters?

For microinverter-based systems, you’ll still see inverter-level sizing pop-ups, but MPPT-specific data will not be shown, since microinverters operate on a per-panel basis and do not rely on stringed configurations.

Warning Messages

To support decision-making, OpenSolar includes automated warnings when design limits are exceeded. These include:

These alerts are intended as guidance. Final design decisions remain in the hands of the solar designer, who can override warnings if necessary based on engineering judgement or product datasheets.

Best Practices

• Always verify string voltages at temperature extremes.

• Adjust site-specific temperature values for accuracy.

• Use the pop-ups and visual indicators as quick checkpoints to ensure your system complies with the manufacturer's specs.

• When in doubt, consult the inverter datasheets or contact support for complex edge cases.

Video Walkthrough: