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If you learned on grid-tie or plain UPS systems, hybrids break two of your habits. This page resets them.

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One box, three sources

A Kent hybrid inverter joins PV DC, battery DC and grid AC in one enclosure, and feeds a Backup port that stays live in an outage. Consequences:
  • “Grid off” does not mean dead. The backup side keeps making AC from battery and PV — that is its job. Isolate all sources, not just the grid breaker.
  • PV cannot be switched off at the panel. Any daylight = string voltage. You isolate it, you never make it zero.
  • Battery DC is low-voltage, high-energy. 51.2 V will not usually shock you through dry skin; hundreds of amps through a dropped spanner is a welding accident. Treat battery work with the same respect as HV work.

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AC vs DC faults behave differently

  • AC arcs self-extinguish at each zero-crossing; DC arcs do not — they sustain until the gap is huge or the source is removed. This is why connectors never part under load and why the Kent G3 manual requires string current below 0.5 A before its DC switch is operated.
  • Reverse polarity on DC is not a “phase swap” — it can damage electronics instantly. Polarity is meter-checked on every string and every battery run before anything is energized.

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Backfeed and the Backup port

Grid supply must land on the Grid port and essential loads on the Backup port — never swapped. Grid voltage arriving on the Backup port destroys the transfer stage.

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Neutral and earth in an outage

In backup operation the neutral-earth relationship is platform-managed. Do not improvise external N-E bonds to stop an RCD tripping — that is a Kent-guided procedure pending OEM written confirmation.
Pending Kent validation — do not configure in the field. [KNB-VAL-04] Backup N-E bond-relay behaviour and the approved RCD scheme for both platforms are under written confirmation. Until published here: never add external N-E bonds, and record the N-E voltage during the outage test on the commissioning checklist for Kent review.

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Common mistakes

  • Testing “dead” with a neon screwdriver — use a proper meter, prove it on a known source first.
  • Assuming the RCD protects the DC side — standard RCDs are AC devices; DC faults need the system’s own protection working, which is why earthing checks matter.

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When to escalate