sigen-diagnose

sigen-diagnose — Inverter Diagnostic Workflow

Step-by-step diagnostic procedure for investigating issues with the Sigenergy ESS system. Designed for systematic troubleshooting rather than quick status checks.

Prerequisites

• sigen-mcp MCP server must be connected
• User should describe the observed symptom if possible

Procedure

Step 1: Check Running State

Call read_plant and look at:

• Running State: Should be Running (1). If Fault (2), Shutdown (3), or Standby (0), there's an operational issue.
• Grid Status: If OffGrid(Auto) or OffGrid(Manual), the inverter is islanded from the grid.

→ Grid goes off-grid during:

• Grid outage / blackout
• Grid voltage/frequency outside limits
• Manual islanding (e.g., for backup mode)

Step 2: Decode Active Alarms

Call read_alarms. If alarms are active:

• Cross-reference with the register definitions in registry.ts (alarm code appendices 2–13)
• PCS alarms (Appendix 2-3): Inverter hardware issues (grid fault, insulation, temperature, DC bus)
• ESS alarms (Appendix 4): Battery issues (SOC low, temp, comms, cell voltage)
• Gateway alarms (Appendix 5): Communication or system-level issues
• DC Charger alarms (Appendix 11): EV charging issues
• Plant alarms (Appendix 12-13): System configuration or sensor issues

Step 3: Check Power Flow

Call read_inverter_detail looking for anomalies:

Symptom	What to Check
Low PV	PV string V/I readings — compare multiple strings. If one string is 0V while others produce, that string may be faulted
Battery not cycling	ESS Power ~0 kW despite PV available. Check if EMS mode is correct. Check read_plant for grid status
Export unexpectedly high/low	Plant active power vs PV generation vs ESS power vs load
Inverter tripping	Running state, internal temp, frequency — may be grid fault

Step 4: Check Battery Health

Call read_battery_status or extract from read_plant:

• SOC vs SOH: Rapid SOC changes with low SOH suggests battery degradation
• Temperature: If battery temp > 45°C or < 0°C, performance may be limited
• ESS Power Availability: In read_plant, compare current ESS power with available max charge/discharge

Step 5: Check EMS Mode

Call read_ems_mode:

• 0 (MaxSelfConsumption): Self-consumption priority — charges battery from PV excess, discharges when load > PV
• 1 (AI): Cloud-optimized mode
• 2 (TOU): Time-of-use — follows configured schedule
• 5 (FullFeedIn): All PV to grid, no self-consumption
• 9 (Custom): Custom parameters

If the system isn't behaving as expected, the EMS mode may be wrong. Check with the user what mode they expect.

Step 6: Check Energy Accumulators

Call read_plant_energy to look at trends:

• Zero PV generation on a sunny day → Possible inverter/panel issue
• Unbalanced import/export → May indicate meter wiring issue or CT clamp problem
• EV energy vs expected → DC charger may not be working (check Step 3)

Common Issue Patterns

Pattern	Likely Cause	Action
OffGrid + no alarms	Grid outage	Wait for grid restoration or check grid connection
OffGrid + PCS alarms	Grid fault (V/Hz outside limits)	Check grid quality, may need electrician
Running but 0 PV	Night time, or PV string fault	Check PV string voltages. If 0V on all strings → night. If 0V on one string → fault
Battery stuck at SOC	Hit charge/discharge limit	Check if set_charge_limit / set_discharge_limit set too low
Export > PV + Battery	Impossible — indicates measurement error	CT clamp may be misconfigured
Temperature > 65°C	Overheating	Check fan operation, ambient temp, ventilation
"Illegal data address" errors	Register not supported on this firmware	Expected for optional registers, not an issue if tools handle gracefully