Path-Q Solar

How much can having one section of a solar array offline reduce production and increase my electricity bill?

Answer

The impact is approximately related to the offline section's share of total potential production, but it can be larger or smaller depending on the system architecture, shading, time of year, and how much electricity you consume. A failed string, optimizer group, microinverter group, or larger subarray does not necessarily represent the same percentage of total output.

Key points

  • Estimate the lost energy by comparing expected production from the affected section with whole-system production.
  • The effect is often greatest during sunny periods when the affected section would otherwise produce substantially.
  • Systems with separate strings, optimizers, or microinverters may isolate a fault differently.
  • The bill increase depends on the lost kilowatt-hours, self-consumption, export treatment, rates, and billing period.
  • Monitoring alerts and production graphs can help identify when the outage began.

What it depends on

  • The affected equipment and its share of array capacity
  • Season, weather, shading, and time since failure
  • System design and how faults affect neighboring modules
  • Household consumption and electricity-billing structure

Risks and trade-offs

  • Assuming the affected physical area equals the lost production can misstate the impact.
  • A fault can remain unnoticed if monitoring communications fail.
  • Leaving a partial outage unresolved increases lost generation and may allow a related fault to worsen.

Information you may need

  • Array layout and equipment configuration
  • Monitoring data before and after the suspected failure
  • Fault start date and any service records
  • Recent bills and normal electricity use if bill impact matters

Your next step

What to do next

Ask the installer or monitoring provider to identify the affected devices and calculate lost production from the fault start date using the system layout and historical output.

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SQ00415