Smart meter wiring made simple
The three wiring mistakes that cause ~90% of meter issues: CT direction, A/B swap, and the wrong RS485 port.
Updated 1 June 2026
If the readings in DeyeCloud look wrong — import and export swapped, battery charging from the grid when it shouldn’t, or zero metering data — it’s almost always one of three things.
1. CT direction
The current transformer (CT) is directional. The arrow (or K → L) printed on the CT must point towards the grid / mains, not towards the load.
- Symptom: import and export are reversed — the system “exports” when the house is actually drawing power.
- Fix: flip the CT 180° on the same cable, or swap the CT polarity in settings if your meter supports it.
2. RS485 A/B swap
The meter talks to the inverter over RS485 (two data wires, A and B). Swapping them kills communication.
- Symptom: no meter data at all, or a meter-communication fault.
- Fix: confirm A→A, B→B between the meter and the inverter’s meter port. If unsure, try swapping the two — it won’t damage anything.
3. Wrong port
Deye hybrids have two RS485 ports — one for the battery BMS and one for the meter. Landing the meter on the BMS port (or vice-versa) means neither talks.
- Symptom: meter and/or battery shows offline despite correct wiring.
- Fix: check the inverter’s port legend — meter to the meter/CT port, battery comms to the BMS port.
Verify it
In DeyeCloud, draw a known load (kettle/oven) and watch the flow: consumption = import (positive), PV surplus = export (negative). If the SDM120 CT meter won’t communicate at all, see SDM120 CT meter ID fix.
