SunSpec Model 64101 — Eltek Inverter Extension
The SunSpec Model 64101 Eltek Inverter Extension is a vendor-specific SunSpec block appended to the standard inverter models on Eltek grid-tied PV inverters. Over Modbus TCP, this template reads the country grid code, AC feeding phase, active power derating (APD) method and reference, and reactive power support (RPS) method, reactive power reference, and cos-phi reference. These registers expose the grid-compliance configuration layer that sits above basic AC output data, giving installers a single-read view of how the inverter is set to interact with local grid codes and utility requirements.
- 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 | ||||
| eltek_country_code | Read | ||||
| eltek_feeding_phase | Read | ||||
| eltek_apd_method | Read | ||||
| eltek_apd_power_ref | Read | ||||
| eltek_rps_method | Read | ||||
| eltek_rps_q_ref | Read | ||||
| eltek_rps_cosphi_ref | Read |
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Use cases
- Verify that the active country code matches the installation site after commissioning or a firmware update.
- Monitor the active power derating method and reference to confirm APD settings align with grid operator requirements.
- Track the reactive power support method over time to detect any unintended configuration changes.
- Alert on a mismatch between the configured feeding phase and the expected single-phase or multi-phase topology.
- Compare the cos-phi reference against the utility contract value to confirm power factor compliance on each site.
Installation
Enable Modbus TCP on the Eltek inverter under the communication or network settings menu, and note the IP address assigned to the device.
Connect the inverter to the same LAN segment as the ModbusCloud Gateway, ensuring port 502 is reachable and no firewall blocks TCP traffic between them.
In your ModbusCloud portal, add the Gateway, import the SunSpec Model 64101 Eltek Inverter Extension template, and set the Modbus unit ID to match the inverter's configured slave address.
Trigger a manual poll and spot-check the eltek_country_code register value against the country code documented in the inverter's configuration menu to confirm the connection is working correctly.
Things to watch for
The gateway connects but all registers return zero. Why?
Model 64101 is a vendor extension block appended after the standard SunSpec models. Its base address is discovered dynamically during a SunSpec scan, not fixed at a known offset. If the template is polled at address 0 without a prior scan, the block may not be at that location on your specific firmware version. Confirm the block offset by scanning the full SunSpec map first.
Why does eltek_country_code show an unexpected value after a firmware upgrade?
Firmware upgrades on Eltek inverters can reset country code and grid-code parameters to factory defaults. Always read back eltek_country_code immediately after any firmware update and cross-check it against the required national grid code for the installation site, since an incorrect country setting affects grid protection thresholds.
The inverter is reachable by ping but Modbus TCP polling times out. What should I check?
Eltek inverters typically expose Modbus TCP on port 502. Confirm that no other client (monitoring software, plant controller) is holding an open TCP connection, as some firmware versions support only one concurrent Modbus client. Close any competing sessions and retry. Also verify the unit ID matches the inverter's configured slave address.
Why does eltek_rps_cosphi_ref return a large unsigned-looking number?
The eltek_rps_cosphi_ref register is typed as int16, meaning values above 32767 in raw form represent negative cos-phi references (leading power factor). If your Modbus client is reading it as uint16, it will display a large positive number. Ensure your client interprets this register as a signed 16-bit integer.
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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