Path-Q Solar

How can voltage drop over a long cable run constrain the size and design of a ground-mounted array?

Answer

A long run can cause voltage drop and power loss, constrain string voltage and current choices, and require larger conductors or a different inverter location. The design must balance array voltage, conductor size, route length, current, losses, equipment limits, and installation cost.

Key points

  • For a given power level, higher voltage generally permits lower current and can reduce conductor losses, subject to equipment limits.
  • Longer runs and higher current increase voltage drop and conductor heating.
  • The location of the inverter can shift the long run to the DC or AC side, with different voltage, current, and equipment considerations.
  • Trenching, conduit, disconnects, grounding, and maintenance access can dominate the practical design.

What it depends on

  • One-way cable distance and routing
  • Array voltage, current, and string configuration
  • Conductor material, size, temperature, and installation method
  • Inverter location and maximum allowable voltage drop

Risks and trade-offs

  • Undersized conductors reduce production, increase heating, and may create safety problems.
  • Larger conductors and additional equipment increase cost and installation effort.
  • A design that is electrically acceptable may still be impractical because of trenching or environmental conditions.

Information you may need

  • Accurate array-to-inverter distance and route
  • Panel and inverter electrical specifications
  • Proposed string voltage and current
  • Conduit, trenching, and installation conditions

Your next step

What to do next

Have the designer calculate voltage drop and conductor requirements for alternative inverter locations and string configurations before finalizing the ground-mount layout.

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SQ02678