Tesla
ALT-05

CT Reading Error — Negative Solar or Grid

Current transformer installed backwards. App shows negative solar or grid values.

Common causes
Solar CT label facing wrong directionGrid/site CT reversed
What to check
STEP 1
Power down system fully before touching CTs. CT label must face toward the source (toward solar inverter or meter, away from breaker).
STEP 2
Rotate CT 180° and power up. Confirm positive readings in app.
Escalate if
CT orientation confirmed correct, readings still wrong — contact Tesla. Gateway-embedded CTs require certified installer.
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More Tesla fault codes

ALT-01
Breaker Open
ALT-02
Device Offline / Gateway Offline
ALT-03
Backup Failed / No Power During Outage
ALT-04
Calibration Discharge to 0%
ALT-06
Follower Failed to Join
Faultpath — Solar & Battery Field Intelligence for Engineers