Accessory Single-phase

SDM120 CT Meter (Single-Phase)

SDM120CTM-40mA + ESCT-TA16

The Eastron single-phase CT meter commonly paired with Deye hybrids — tells the inverter what the whole house is importing or exporting so zero-export and self-consumption control work. Polled over RS485 Modbus at 9600 baud; ships with the ESCT-TA16 clip-on CT.

Residential

Role: External grid meter for Deye hybrids
Phase: Single (three-phase sites use the SDM630MCT)
Communication: RS485 Modbus, 9600 baud
CT: ESCT-TA16 clip-on, 40 mA secondary
Meter ID: The inverter polls a fixed Modbus address — commonly 1

View datasheet Ask an engineer

Specifications

Communication

Bus: RS485 (A/B two-wire) to the inverter meter port
Protocol / baud: Modbus RTU, 9600
Address: Must match the ID the inverter polls (commonly 1) — see the meter-ID guide for the locked-variant workaround

Measurement

CT: ESCT-TA16 clip-on current transformer, 120 A primary / 40 mA secondary, 16.3 mm aperture
CT placement: Grid side, all consumption and solar downstream — arrow orientation per the wiring guide

Terminals

1 · 2: CT secondary — S1 (white) to 1, S2 (black) to 2
3 · 4: Voltage reference: 3 = N, 4 = L. Also powers the meter — it needs no separate supply
5 · 6 · 7: Pulse outputs — not used on a Deye system
8 · 9 · 10: RS485: 8 = G, 9 = B−, 10 = A+

Set-up

Entering set-up: Hold the single front button for 3 s; click to scroll
Factory defaults: Address 001, baud 2400 — the baud always has to be changed
CT ratio: Set CT 1 = 120 for the ESCT-TA16. On MID meters the CT ratio can be set once only

Why it matters

A Deye hybrid can only manage what it can see. Without a working external meter the inverter knows its own output but not the site’s grid flow — so zero-export limits, self-consumption logic and the consumption curves in DeyeCloud all depend on this one small box being wired and addressed correctly.

The two classic failure modes are covered by their own pages: the meter answering on the wrong Modbus ID (SDM120 meter ID fix) and the CT clipped on backwards or in the wrong place (CT direction reversed). Three-phase sites use the SDM630MCT with the same CT.

⚠ Do not wire it to the figure in the Deye manual

The Deye All-in-One manual’s “System connection diagram for the Eastron meter” (printed p.24) draws an SDM230. That is a direct-connect meter — the mains runs in on terminals 1/3 and out on 2/4, RS485 on 5/6/7 — and Australia does not use it. Confirmed with Deye application engineering, 3 September 2026.

What we ship is CT-operated: the mains never enters the meter. Terminals 1 and 2 are the CT secondary, not a current path. Wire it to the Eastron manual linked under Documents, and set Advanced Function → Meter Select = Eastron-1P on the inverter.

The CT

ESCT-TA16, 120 A in, 40 mA out, split core, 16.3 mm aperture, 1 m white/black leads. The polarity marks sit on P1 and on the white lead, so white is S1. Eastron’s own instruction is “P1 in, P2 out, and the secondary must never be open-circuited” — clamp it on the grid live with the case arrow pointing away from the grid, and land both leads before the conductor goes live.