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The CT is the hybrid’s eyes on the grid connection. Everything smart — self-use, export limiting, the energy display — is only as correct as this one clamp.
For trained/authorized installers only. Isolate the AC conductor before clamping anything around it.

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What the CT is for

A CT (current transformer) clips around the grid conductor and reports the current flowing through it. From that, the inverter knows whether the site is importing or exporting, and how much — the signal that drives self-use logic, zero-export control and the power figures on the display. No healthy CT signal, no working control.

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The clamp rule

  • The CT clamps around one conductor: the live. Clamping live and neutral together cancels the magnetic fields — the CT reads 0 W and the control logic goes blind.
  • Close the clamp until it clicks fully shut — a half-latched CT under-reads.
  • Where it clamps and which way the arrow faces is its own discipline: Direction & Location.

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Ratio discipline

A CT reports a scaled-down current; the ratio setting tells the inverter the scale. Wrong ratio = every power figure wrong by a large factor, and export limits enforced against the wrong numbers.
Pending Kent validation. [KNB-VAL-08] The shipped CT scheme and ratio per Kent SKU are under confirmation. Until published here: read the ratio off the shipped CT’s nameplate and set exactly that — never assume a default. On the Kent G3, the box-kit CT and the meter-scheme CT carry different ratios; the kit table is on Kent G3 CT & Meter.

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Lead length — the quiet killer

The CT’s analog signal is millivolt-class: long or improvised extensions pick up noise, and noise reads as phantom import/export that the control chases.
  • The Kent G3 box kit ships with a 1 m, 2.3 mm² CT lead — that is the design length.
Pending Kent validation. [KNB-VAL-23] The approved CT-lead extension method per Kent SKU is under confirmation. Until published here: do not extend CT leads. If the supplied lead cannot reach the grid connection point, use the platform’s meter scheme instead — never a spliced-on length of flex.

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CT scheme vs meter scheme

Both platforms can sense the grid either with CT(s) directly on the conductor or through a supported energy meter (which carries its own CTs and talks RS485 to the inverter). One scheme per site — if CTs are connected on the Kent G3, the smart meter is not essential. Platform specifics: Kent M1 CT & Meter · Kent G3 CT & Meter.

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Common mistakes

  • CT around live + neutral — load reads 0 W.
  • Ratio typed from memory instead of the shipped CT’s nameplate. [KNB-VAL-08]
  • CT lead extended with random 1.5 mm flex “just two metres” — phantom export follows. [KNB-VAL-23]
  • Half-latched clamp that never clicked — under-reads until someone leans on it.

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When to escalate