Turning a Cheap OOYCYOO MPPT Solar Controller into a Real Telemetry System
There’s a certain kind of frustration that comes with inexpensive hardware: it works, but it doesn’t tell you anything useful. That’s exactly where I found myself with an OOYCYOO MPPT solar charge controller. It was happily charging batteries, but beyond a tiny LCD panel, there was no meaningful way to monitor performance, integrate it into dashboards or understand what was actually happening over time. So instead of replacing it, I decided to listen to it. What came out of that experiment is a simple but surprisingly powerful approach: passively tapping the RS485 data stream, decoding the controller’s undocumented protocol and publishing clean telemetry into MQTT for Node-RED, Grafana or Home Assistant. Important Disclaimer – since you will be doing something experimental, follow the instructions carefully and I take no responsibility for any equipment you might damage. The Core Idea: Passive RS485 Monitoring Most people approach this kind of problem by trying to talk to the con...