SunSpec Model 701 — DER AC Measurement
SunSpec Model 701, known as DERMeasureAC, is the approved AC measurement information model for Distributed Energy Resources such as solar inverters and battery storage systems. Accessed over Modbus TCP, it exposes a comprehensive read-only register set covering per-system and per-phase active power, apparent power, reactive power, power factor, current, line-to-line and line-to-neutral voltage, grid frequency, cumulative injected and absorbed energy in both watt-hours and var-hours, six temperature points, throttling state, DER operating mode, alarm bitfields, and SunSpec scale factors. This template gives installers a single standardized interface for monitoring any IEEE 1547-2018 compliant DER without device-specific register hunting.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 72, read only
- Brand
- SunSpec
- Last updated
Registers (72)
72 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| actype | Read | ||||
| st | Read | ||||
| invst | Read | ||||
| connst | Read | ||||
| alrm | Read | ||||
| dermode | Read | ||||
| w | W | Read | |||
| va | VA | Read | |||
| var | Var | Read | |||
| pf | Read | ||||
| a | A | Read | |||
| llv | V | Read | |||
| lnv | V | Read | |||
| hz | Hz | Read | |||
| totwhinj | Wh | Read | |||
| totwhabs | Wh | Read | |||
| totvarhinj | Varh | Read | |||
| totvarhabs | Varh | Read | |||
| tmpamb | °C | Read | |||
| tmpcab | °C | Read | |||
| tmpsnk | °C | Read | |||
| tmptrns | °C | Read | |||
| tmpsw | °C | Read | |||
| tmpot | °C | Read | |||
| wl1 | W | Read | |||
| val1 | VA | Read | |||
| varl1 | Var | Read | |||
| pfl1 | Read | ||||
| al1 | A | Read | |||
| vl1l2 | V | Read | |||
| vl1 | V | Read | |||
| totwhinjl1 | Wh | Read | |||
| totwhabsl1 | Wh | Read | |||
| totvarhinjl1 | Varh | Read | |||
| totvarhabsl1 | Varh | Read | |||
| wl2 | W | Read | |||
| val2 | VA | Read | |||
| varl2 | Var | Read | |||
| pfl2 | Read | ||||
| al2 | A | Read | |||
| vl2l3 | V | Read | |||
| vl2 | V | Read | |||
| totwhinjl2 | Wh | Read | |||
| totwhabsl2 | Wh | Read | |||
| totvarhinjl2 | Varh | Read | |||
| totvarhabsl2 | Varh | Read | |||
| wl3 | W | Read | |||
| val3 | VA | Read | |||
| varl3 | Var | Read | |||
| pfl3 | Read | ||||
| al3 | A | Read | |||
| vl3l1 | V | Read | |||
| vl3 | V | Read | |||
| totwhinjl3 | Wh | Read | |||
| totwhabsl3 | Wh | Read | |||
| totvarhinjl3 | Varh | Read | |||
| totvarhabsl3 | Varh | Read | |||
| throtpct | Pct | Read | |||
| throtsrc | Read | ||||
| a_sf | Read | ||||
| v_sf | Read | ||||
| hz_sf | Read | ||||
| w_sf | Read | ||||
| pf_sf | Read | ||||
| va_sf | Read | ||||
| var_sf | Read | ||||
| totwh_sf | Read | ||||
| totvarh_sf | Read | ||||
| tmp_sf | Read | ||||
| mnalrminfo | Read |
Loading registers…
Send your device list
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 total and per-phase active power to verify that each phase carries the expected generation load.
- Track cumulative injected and absorbed energy registers over time to produce accurate net-metering reports.
- Alert on alarm bitfield changes to detect fault conditions on a DER before they cause grid disconnection.
- Compare per-phase voltage and current to identify imbalance conditions requiring site investigation.
- Verify throttling percentage and throttle source to confirm why output is being curtailed during grid events.
Installation
Enable Modbus TCP on the DER device: log into the device web interface and activate the Modbus server under the communication or Modbus settings section, noting the TCP port (default 502).
Connect the DER device to the same LAN segment as the ModbusCloud Gateway, confirm the device has a reachable static or DHCP-reserved IP address, and that port 502 is not blocked by a firewall.
In the ModbusCloud portal, add the Gateway, create a new device, import the SunSpec Model 701 template, and enter the device IP address, port, and Modbus unit ID as configured on the DER.
Trigger a manual poll and spot-check registers w (active power) and hz (frequency) against the device's own display to confirm correct scaling and byte order before saving the configuration.
Things to watch for
All values read as zero or the SunSpec NaN sentinel. Why?
SunSpec Model 701 registers are at model-relative offsets, not fixed absolute addresses. The actual holding register base shifts depending on which models precede it in the device's SunSpec map. Perform a full SunSpec model scan (read from address 40001 and walk the model chain) to locate the correct base address before reading any point.
Power and energy readings look wrong by a factor of 10 or 100. What is happening?
All measurement registers in Model 701 are raw integers that must be multiplied by 10 raised to the power of the corresponding scale factor register (for example, w_sf for active power). The scale factor is a signed int16 and may be negative. Read the relevant _sf register and apply it before displaying or storing the value.
The gateway connects but per-phase registers (wl2, wl3) all return NaN. Is this a wiring problem?
NaN on per-phase registers is expected for single-phase and split-phase devices: only L1 registers are populated in those configurations. Check the actype register first. If actype confirms three-phase but L2 and L3 registers still return NaN, the device firmware may not implement those optional points; consult the device PICS document.
Frequency register hz returns an implausible value. How do I interpret it?
The hz register is a uint32 spanning two Modbus registers. SunSpec encodes all values in big-endian byte order across registers. If your Modbus client is reading the two 16-bit words in the wrong order, the result will be wrong. Confirm your client uses big-endian word order, then apply hz_sf to obtain hertz.
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.
Want to see how it works?
