EVCC Custom Hardware Design

[TammyCutzer]

Moin,

I got tired of having a messy setup with USB-to-RS485 dongles dangling off a standard Raspberry Pi to talk to my FoxESS solar inverter. To clean up my setup, I designed a compact, custom carrier board for the Raspberry Pi Compute Module 4 (CM4).

Since CM4 modules (and Lite versions) are currently pretty affordable (picked mine up cheap from Reichelt), this felt like a fun project to sharpen my PCB layout skills and build a neat, all-in-one solution.

Key Features

• Dual Isolated RS485: Dedicated channels for simultaneous communication with the FoxESS inverter and the Smart Meter.
• Onboard Relay: Integrated relay output to trigger heat pump PV-boost / Smart Grid (SG Ready) modes based on excess solar.
• Ethernet Connection: Reliable wired networking for local Home Assistant / MQTT integration.
• Compact Form Factor: Replaces a Pi + USB hubs + RS485 dongles with a single clean board.
• Power Supply via USB-C 5V 3A
• HDMI for Debug, as well as Voltage- and UART Rx/Tx header pins. Not needed now, but i had no high hopes the board would fire up

Project Details

The PCB was manufactured via J**P*B. Designing it was a great learning process, particularly around signal isolation and practical layout for home automation.

3D Print / enclousre is still under construction. I just have an Ender3 availabe at the moment.

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Interest Check / Availability

This was originally just a personal project to tidy up my setup, but if there's enough interest from the community, I'd be happy to order a larger batch of fully assembled boards to lower the unit cost for everyone.

If you'd be interested in getting one, please leave a reaction on this issue / star the repo or drop a comment below!