Determining String Design for an Inverter

Summary

Go to AI and ask:

For a given inverter (provide link or specs) and solar panels (provide link or specs) - design the number of strings and number of PV panels in each string based on the inputs of the inverter.

The procedure, if you want to verify the AI result, is:

• Essentially, take Voc, and compare to max voltage of inverter (typically 500 VDC)
• Correct for low temperature - Voc increase ≈ 3% per 10°C below 25°C. Such as 13.5% for -20C [1]
• Determine max panels that fit within max voltage
• Use max current of input to determine if you should parallel strings
• For the total number of strings, check max power of PV and make sure it is within the rated power input rating of the inverter.

PV String Design Prompt

Design the optimal PV string configuration for a solar inverter system.

Goal

• Maximize PV capacity within safe electrical limits
• Determine:
  • Panels in series per string
  • Number of parallel strings per MPPT input
  • Total system size (kW DC)

Location

• Location (city/state/country):
• Minimum expected ambient temperature:

PV Module Specifications

• Panel model:
• Power (W):
• Voc (V):
• Vmp (V):
• Isc (A):
• Imp (A):
• Voc temperature coefficient (%/°C):

Inverter Specifications

• Inverter model:
• Max DC input voltage (V):
• MPPT voltage range (V):
• Number of MPPT inputs:
• Max input current per MPPT (A):
• Max short-circuit current per MPPT (A):
• Max PV power per MPPT (W):
• Max total PV power (W):

Design Preferences (optional)

• Prefer maximum power or conservative margin:
• Allow DC oversizing (yes/no, and % if yes):
• Fixed or mixed string lengths:
• Any shading/orientation differences between arrays:

Required Output

• Maximum panels in series (based on cold-corrected Voc)
• Recommended panels per string
• Maximum strings per MPPT (based on current and power limits)
• Final configuration (strings × panels × MPPTs)
• Total DC system size (kW)
• Verification against:
  • Max DC voltage
  • MPPT operating voltage range
  • Input current per MPPT
  • Power per MPPT
  • Total inverter PV limit
• Identification of the limiting constraint (voltage, current, or power)

Design Principle

• Series count is determined by voltage limits (Voc and MPPT range)
• Parallel string count is determined by current and power limits