my-PV AC ELWA-E

Use cases

• Monitor water temperature and heating power in real time on a cloud dashboard for your customer.
• Create an alert when water temperature drops below a defined threshold for more than 15 minutes.
• Remotely activate boost mode before a scheduled maintenance visit to verify heater operation.
• Adjust the power setpoint based on available PV surplus data from a paired inverter template.
• Schedule boost start and stop hours remotely to align with low-tariff periods or peak solar generation.
• Track hardware temperature over time to detect overheating or ventilation issues early.

Installation

1. 1Connect the my-PV AC ELWA-E to the same local network as the ModbusCloud gateway (MCG or MLP series) using an Ethernet cable or a shared network switch.
2. 2Open the AC ELWA-E web interface in a browser and navigate to the control settings page.
3. 3Set the control type to Modbus TCP and set the control timeout to 60 seconds, then save the configuration.
4. 4Note the IP address assigned to the AC ELWA-E and ensure it has a static IP or a DHCP reservation to prevent address changes.
5. 5In the ModbusCloud portal, add a new device using the my-PV AC ELWA-E template and enter the device IP address and Modbus TCP port (default 502).
6. 6Verify communication by checking that water temperature and power readings appear on the ModbusCloud dashboard.

Things to watch for

01

The gateway cannot connect to the AC ELWA-E. What should I check?

Verify that the control type is set to Modbus TCP in the AC ELWA-E web interface. Confirm both the gateway and the heater are on the same subnet and that no firewall is blocking TCP port 502.

02

Readings show zero or do not update. Why?

Ensure the control timeout is set to 60 seconds in the AC ELWA-E settings. If the timeout is too short, the device may stop responding between polling cycles. Also confirm the IP address in ModbusCloud matches the current device IP.

03

What data type do the registers use?

All registers on the AC ELWA-E are uint16. The template is preconfigured with this data type, so no manual byte order or scaling adjustments are needed.

04

Can I control the AC ELWA-E and still use its internal PV surplus logic?

When Modbus TCP is selected as the control type, the device expects external power setpoint commands. Its internal frequency-based surplus control is disabled. You must manage the power setpoint through the template or another external source.

Registers (16)

15 read / 12 write

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