SunSpec Model 111 — Inverter (Single Phase) FLOAT
SunSpec Model 111 is an open, vendor-neutral Modbus TCP register model defined by the SunSpec Alliance for monitoring single-phase PV inverters, with companion models 112 (split phase) and 113 (three phase) sharing the same layout. This template reads AC-side measurements including per-phase current, phase-to-phase and phase-to-neutral voltage, active power, apparent power, reactive power, power factor, and cumulative energy production. DC-side registers cover array current, voltage, and power, while four temperature registers track cabinet, heat sink, transformer, and other sensors. Operating state, standard event bitfields, and four vendor event bitfields complete the picture, giving installers a full health snapshot of any SunSpec-certified inverter.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 33, read only
- Brand
- SunSpec
- Compatible models
- SunSpec Model 112 — Inverter (Split Phase) FLOAT · SunSpec Model 113 — Inverter (Three Phase) FLOAT
- Last updated
Registers (33)
33 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| a | A | Read | |||
| apha | A | Read | |||
| aphb | A | Read | |||
| aphc | A | Read | |||
| ppvphab | V | Read | |||
| ppvphbc | V | Read | |||
| ppvphca | V | Read | |||
| phvpha | V | Read | |||
| phvphb | V | Read | |||
| phvphc | V | Read | |||
| w | W | Read | |||
| hz | Hz | Read | |||
| va | VA | Read | |||
| var | var | Read | |||
| pf | Pct | Read | |||
| wh | Wh | Read | |||
| dca | A | Read | |||
| dcv | V | Read | |||
| dcw | W | Read | |||
| tmpcab | °C | Read | |||
| tmpsnk | °C | Read | |||
| tmptrns | °C | Read | |||
| tmpot | °C | Read | |||
| st | Read | ||||
| stvnd | Read | ||||
| evt1 | Read | ||||
| evt2 | Read | ||||
| evtvnd1 | Read | ||||
| evtvnd2 | Read | ||||
| evtvnd3 | Read | ||||
| evtvnd4 | Read |
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If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Monitor AC active power output continuously to verify the inverter is producing at expected levels throughout the day.
- Track cumulative watt-hour production over time to validate yield against design estimates and flag underperformance.
- Alert on elevated heat sink or cabinet temperature readings to catch thermal issues before they cause forced shutdowns.
- Compare DC input power against AC output power to calculate real-time conversion efficiency and detect degradation.
- Inspect the evt1 and evt2 bitfields to identify active fault codes and correlate them with production drops in the portal.
Installation
Enable Modbus TCP on the inverter by logging into its web interface or display panel and navigating to the communication or Modbus section; confirm port 502 is active and note the assigned unit ID.
Connect the inverter to the same LAN segment as the ModbusCloud Gateway using a standard Ethernet cable, then verify network reachability with a ping from a laptop on the same subnet.
In the ModbusCloud portal, add a new device, select the ModbusCloud Gateway, import the SunSpec Model 111 template, and enter the inverter's IP address and unit ID in the device configuration fields.
Spot-check the connection by opening the live register view and confirming that the w (AC active power) and hz (grid frequency) registers return plausible values during daylight hours.
Things to watch for
All registers return NaN or zero. What is wrong?
SunSpec inverters report NaN for unimplemented or unsupported registers. Verify the inverter is running (st register should not indicate off or sleeping state), that Modbus TCP is enabled and not just the RTU interface, and that the model block start address in the portal matches the actual offset reported by the inverter's SunSpec discovery scan.
The gateway connects but the id register reads an unexpected value.
The id register at address 0 within the model block identifies the phase topology: 111 for single phase, 112 for split phase, 113 for three phase. If you see 112 or 113, the inverter is presenting a different model variant. Select the matching template in the portal to ensure all phase registers are mapped correctly.
Phase B and C current and voltage registers always read zero on a single-phase inverter.
This is normal. On a single-phase inverter (model ID 111), registers apha carries the sole phase current and phvpha the sole phase voltage. Registers aphb, aphc, phvphb, phvphc, and all phase-to-phase voltage registers are not implemented and will return zero or NaN per the SunSpec specification.
Float32 values look scrambled or implausibly large. How do I fix byte order?
SunSpec float32 registers use big-endian word order: the most significant 16-bit word occupies the lower register address, the least significant word the next address. If your readings appear garbled, confirm that the ModbusCloud Gateway is configured for big-endian (Modbus standard) word order. Swapping the two words typically resolves implausible values immediately.
Knowledge base articles for this device
SunSpec Modbus: one register map for many inverters
SunSpec Modbus is the open register map SMA, Fronius, SolarEdge and Kostal share. The layout, int+SF vs float, the TCP port per brand and reading a mixed fleet.
Fronius Modbus: read a Symo GEN24 over Modbus TCP
Fronius Modbus explained: enable Modbus TCP on the Symo GEN24 on port 502, choose between int+SF and float, read the right SunSpec registers and scale them correctly. Practical guide for solar installers.
SMA Modbus: reading a Sunny Boy over Modbus TCP (installers)
SMA Modbus explained: enable the Modbus TCP server on port 502, choose between the SMA profile (unit ID 3) and SunSpec (unit ID 126), read the right registers, and handle the NaN values at night. Practical guide for installers.
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