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SESK: Stuff Everyone Should Know · sesk.info/solar-optimizer-1-volt

When power optimizers shut down, about how much voltage does NREL say each one outputs?

About 1 volt, so the string to the inverter is de-energized.

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  1. About 120 volts
  2. About 600 volts
  3. About 1 volt ✔

Why: Optimizers sit at each panel. When shut down, each outputs only about 1 volt, so the wiring that runs from the panels to the inverter is effectively de-energized.

Huh, didn't know that: NREL notes that disconnects and similar parts cost more in DC versions than in AC versions.

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References

Answer: About 1 volt. Optimizers sit at each panel. When shut down, each outputs only about 1 volt, so the wiring that runs from the panels to the inverter is effectively de-energized.

  1. NREL: Best Practices for O&M of PV and Energy Storage Systems, 3rd ed. (2018) docs.nlr.gov/docs/fy19osti/73822.pdf
    Each power optimizer will output only 1 V, meaning that the string connecting the modules to the inverter is also de-energized.
    Checked 2026-10-10.

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