Solis Inverter 1015 NO-GRID Alarm: AC MCB Tripping and Triage Guide

Key Takeaways

• Alarm code 1015 signals that the inverter detects no alternating-current grid supply or that the protective AC miniature circuit breaker has tripped.
• Check whether the breaker trips immediately on connection or only when the inverter enters generation mode after start run.
• Always isolate both AC and DC supplies using external switches before inspecting terminals to prevent electrical shock.
• Escalate to an MCS-certified electrician if breaker replacement or consumer unit distribution board rewiring is necessary.

Why is my Solis inverter showing 1015 NO-GRID?

When a Solis inverter displays alarm code 1015, it has disconnected from the grid because it cannot detect voltage on its alternating-current terminals. This diagnostic event is titled 1015 - NO-GRID (AC MCB Tripping) in the manufacturer technical service database.

In British homes, this condition usually stems from one of four root causes: an external utility power cut on the local distribution network, an open AC rotary isolator, an undersized or worn circuit breaker in the consumer unit, or incorrect terminal connection at the inverter AC gland. For general grid connection standards governing small generators, see our ENA EREC G98 micro-generator guide.

Diagnostic steps for 1015 NO-GRID and breaker trips

To isolate whether the fault originates in the utility supply, the external wiring, or the inverter hardware, follow this structured troubleshooting workflow:

1. Verify Circuit Breaker Sizing: Check the rating of the MCB and calculate whether the rating is less than the recommended specification for your inverter model.
2. Inspect for Mechanical Breaker Fatigue: If an existing breaker has tripped repeatedly under thermal load, replace the AC breaker with a new one.
3. Test Generation Mode Behavior: Check whether the MCB is tripping once the inverter comes to generation mode after start run. Technicians should test inverter power control by 10% and 20% to see if the trip occurs under partial load.
4. Document Tripping Timing: Take an AC side tripping video after connecting or disconnecting the AC connector to document the exact moment of failure for warranty review.
5. Verify AC Gland Polarity on New Systems: If the installation is new, check that connectivity is proper at the AC gland, making sure the AC cable connects properly in the connector terminal only according to the polarity clearly mentioned on the AC gland.

Multimeter voltage verification at the AC gland

Testing supply voltages confirms whether utility power is reaching the inverter chassis. All voltage testing must be conducted by a qualified electrician using insulated test probes.

If suspecting loose contact, properly connect the cable after disconnecting from the connector or AC distribution board. For comprehensive domestic wiring compliance, refer to our UK solar electrical installation guide.

Menu settings and data collection

If physical wiring and breaker ratings are confirmed, inspect internal software parameters before requesting warranty service:

• Grid Software State: From the advance setting menu, ensure that Grid-ON is selected so the inverter is permitted to export.
• Information Menu Readings: Take complete reading of information menu parameters including DC1, DC2, DC3, DC4, then VA, VB, VC or VGrid, then Status (Error), and Total energy.
• Diagnostic History: Take reading from advance info including Alarm messages, version, running messages, and warning messages.
• Photographic Evidence: Take ACDB, DCDB close and clear photo, inverter serial number which is stuck on the inverter body, and inverter complete installation photo.

Tracking grid generation telemetry also ensures your export credits remain intact under your Smart Export Guarantee tariff.

Safety rules for AC circuit troubleshooting

Working with mains distribution boards presents direct electric shock hazards.

• Double-Pole Isolation: Always switch off the AC rotary isolator and open the consumer unit circuit breaker before inspecting or tightening terminals.
• Insulated Hand Tools: Only use insulated tools when securing terminals inside distribution boards or AC connectors.
• Verify Dead Before Contact: Always verify that conductors are de-energized using a calibrated voltage indicator before touching metal terminals.
• Do Not Cross-Wire Phases: In three-phase installations, never short or bridge phases together; improper phase bridging causes instantaneous short-circuit trips. For utility notification rules, consult our DNO G98 notification guide.

When to contact your solar installer

Contact an MCS-certified installer or electrical contractor if:

• The circuit breaker trips instantly even when the inverter DC switch is turned off.
• Terminal burning or heat damage is visible at the AC connector or consumer unit.
• Grid voltage readings between neutral and earth show abnormal voltage floating.
• Breaker replacement does not resolve generation-onset tripping, indicating internal power module failure.