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 — both the way the arrow faces and which way the two CT leads land have to be right.
- Arrow → inverter. Clip the CT on the grid/mains incomer with its arrow (or K → L) pointing towards the inverter. This is the standard across the whole Deye range.
- Leads: white left, black right. Land the CT’s white lead on the left terminal and the black lead on the right.
- Exception — SUN-10/12K SG02LP1 (single-phase LV): keep the arrow towards the inverter, but reverse the leads — white on the right, black on the left. The swapped leads set the correct direction on this one model.
If import and export read reversed — the system “exports” while the house is actually drawing power — flip the CT 180° so the arrow faces the inverter, or swap the white/black leads, whichever brings the reading the right way round. Then re-check in DeyeCloud (below).
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 grid figure: drawing from the grid reads positive (import); exporting surplus reads negative (sell to grid). PV and load always read positive — only grid and battery change sign, so a negative PV or load figure is a metering fault, not an export. Full sign convention in import / export readings are reversed. If the SDM120 CT meter won’t communicate at all, see SDM120 CT meter ID fix.
