SunSpec Model 713 — DER Storage Capacity
SunSpec Model 713 is a standardised Distributed Energy Resource information model that exposes the storage capacity block of any SunSpec-compliant battery system over Modbus TCP. Part of the IEEE 1547-2018 DER profile, this template reads nameplate energy capacity (whrtg), available stored energy (whavail), state of charge (soc), state of health (soh), and the operational status register (sta), together with their paired scale factors. Installers and asset managers can track actual usable energy against nameplate capacity across any compliant battery, regardless of vendor, without reconfiguring the ModbusCloud Gateway per device.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 9, read only
- Brand
- SunSpec
- Last updated
Registers (9)
9 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| whrtg | WH | Read | |||
| whavail | WH | Read | |||
| soc | Pct | Read | |||
| soh | Pct | Read | |||
| sta | Read | ||||
| wh_sf | Read | ||||
| pct_sf | Read |
Loading registers…
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Use cases
- Monitor state of charge in real time to verify a battery is cycling within its expected operating band.
- Track state of health over months to detect capacity fade before it affects site backup autonomy.
- Compare available stored energy (whavail) against nameplate capacity (whrtg) to quantify seasonal degradation.
- Alert on unexpected sta status codes to catch charging or fault conditions before they escalate.
- Report daily energy availability trends across multiple SunSpec-compliant battery sites from a single portal view.
Installation
Enable Modbus TCP on the battery inverter or battery management system: navigate to the communication or Modbus section of the device web interface and activate Modbus TCP on port 502 (or the port configured for your site).
Connect the device to the same LAN segment as the ModbusCloud Gateway, confirm the device IP is reachable from the Gateway, and note the assigned Modbus unit ID.
In the ModbusCloud portal, add a new device, select the SunSpec Model 713 DER Storage Capacity template, and enter the device IP address and unit ID. Because SunSpec uses a dynamic register map, ensure the base address offset is configured to match where Model 713 appears in the device's SunSpec block.
Verify the connection by checking live readings for soc and whavail in the portal: soc should reflect the battery's current charge level and whavail should be less than or equal to whrtg after applying the wh_sf scale factor.
Things to watch for
Why do whrtg and whavail show values that seem ten times too large?
Both registers are raw integers and must be multiplied by 10 raised to the power of the wh_sf register. If wh_sf reads as a negative number such as -1, divide the raw value by 10. Always read wh_sf first and apply it before presenting watt-hour values in any dashboard formula.
Why does soc read 0 or 65535 even though the battery is charged?
A value of 0xFFFF (65535) is the SunSpec Not Implemented sentinel, meaning the device did not populate this register. Confirm the battery firmware supports Model 713 with the soc point enabled. On some devices, SoC is only reported in the vendor-specific model and the 713 block is partially populated.
The Gateway connects but no register values update after the first read.
SunSpec devices use a dynamic register map: Model 713 does not sit at a fixed absolute address. If you configured a static base offset that does not match the actual model position in the device's SunSpec chain, reads will return errors or stale data. Use the ModbusCloud Gateway SunSpec auto-discovery or manually scan from the SunS marker to find Model 713's true start address before committing to a fixed offset.
The sta register returns an unexpected numeric code. What does it mean?
The sta register is an enumeration whose numeric values are defined in the SunSpec DER Information Model specification. Common values include charging, discharging, standby, and fault states. If an undocumented value appears, check the device manufacturer's Modbus supplement for vendor-specific extensions to the standard enumeration, as some implementations add proprietary states above the reserved range.
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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