Marstek Jupiter C Plus Battery Storage (pv)
The Marstek Jupiter C Plus is an all-in-one plug-and-play battery storage system with an integrated microinverter, targeting residential balcony and plugin solar installations. It combines a LiFePO4 battery starting at 2.56 kWh, expandable to 10.24 kWh, with up to 2,400 W of solar input across four independent MPPT channels and 800 W of on-grid output. This Modbus RTU template reads live PV production across all four MPPT channels: power_a, power_b, power_c, and power_d. Connecting the Jupiter C Plus to the ModbusCloud Gateway gives installers a continuous, cloud-accessible record of per-channel solar yield without relying on the Marstek app.
- Protocol
- Modbus RTU
- Connection
- RS485
- Registers
- 4, read only
- Brand
- Marstek
- Last updated
Registers (4)
4 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power_a | W | Read | |||
| power_b | W | Read | |||
| power_c | W | Read | |||
| power_d | W | 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 per-MPPT PV power in real time to verify each connected solar panel string is producing as expected.
- Compare power_a through power_d over time to detect shading or soiling affecting individual panel strings.
- Track total PV generation by summing all four channels to report daily solar yield per site.
- Alert on a channel dropping to zero during daylight hours to spot a failed panel connection or MPPT fault.
- Verify seasonal PV output trends across all four MPPT inputs to plan expansion battery additions.
Installation
Enable Modbus communication on the Jupiter C Plus: the RS485 interface is active by default, but confirm the unit is powered on and the RS485 connector (5-pin Weipu SP17, pins 1 and 2) is accessible at the rear of the device.
Wire the RS485 bus: connect pin 1 (A+) and pin 2 (B-) of the Jupiter C Plus RS485 connector to the corresponding A and B terminals of the ModbusCloud Gateway using a shielded twisted-pair cable.
In the ModbusCloud portal, add the ModbusCloud Gateway to your site, import the Marstek Jupiter C Plus Battery Storage (pv) template, and set the Modbus unit ID to 1 and baud rate to 115200, 8N1.
Verify the connection by checking that registers power_a through power_d return non-zero values during daylight hours in the portal's live register view.
Things to watch for
All four power registers return zero even in full sunlight. Why?
Confirm that PV panels are correctly connected to the MC4 inputs on the Jupiter C Plus and that the unit is in discharge or auto mode, not manually disabled. Also check that the RS485 baud rate on the adapter or Gateway is set to 115200, not the Modbus standard 9600 or 19200, as the Jupiter C Plus uses a non-standard rate.
The Gateway connects but register values look garbled or jump randomly.
The Jupiter C Plus RS485 interface requires 8 data bits, no parity, and 1 stop bit (8N1). Any mismatch in parity or stop bits causes corrupted frames. Also verify that A and B wires are not swapped: pin 1 is A+ and pin 2 is B-. Reversing them produces no response or noise.
Only one or two channels read correctly; others always read zero.
Each register corresponds to a specific MPPT input (A through D). If fewer than four panels are connected, unoccupied MPPT channels will legitimately report zero. Verify the actual panel-to-MPPT wiring matches which channels you expect to see active in the portal.
A second system on the same RS485 bus cannot connect alongside the Gateway.
The Jupiter C Plus allows only one active Modbus connection at a time over its RS485 interface. If another tool or system is polling the device simultaneously, the Gateway will receive incomplete or no responses. Use the ModbusCloud portal as the single polling master, or add a Modbus proxy between the adapter and the consumers.
Want to see how it works?
