I’ve been diving into the world of renewable energy lately, and I’m really excited about the idea of achieving a zero feed-in photovoltaic system. I’ve been working with Shelly devices and OpenDTU to monitor and control my energy usage, but I’m hitting a bit of a roadblock in my setup. Let me walk through what I’ve done so far and where I’m stuck.
First off, I’ve set up a small photovoltaic system and integrated it with my Shelly 3EM energy monitor. The goal is to ensure that the inverter only draws power when the Shelly detects a positive power value between 1 and 600 W. If the value is negative, the inverter should reduce its output accordingly. I’ve found some helpful examples online, but the calculations in the function node are a bit confusing to me. I’m not entirely sure how to translate the power readings from the Shelly into actionable commands for the inverter.
I’ve also been exploring how to send values to the inverter using MQTT in Home Assistant. From what I’ve gathered, it’s possible to send commands directly through MQTT Explorer, but I’m not sure how to replicate this functionality in Node-RED. I’ve attached some screenshots of my current setup, but I’d really appreciate some guidance on which functions and parameters to use in Node-RED to make this work seamlessly.
Another thing I’m curious about is whether there’s a more efficient way to handle the power adjustments. I’ve seen some people use advanced automation rules, but I’m not sure if that’s necessary for my setup. I’d love to hear from others who’ve successfully implemented similar systems—what tools and techniques did you find most useful?
In the meantime, I’m going to keep tinkering with the Node-RED flows and see if I can get a basic version working. If anyone has any tips or resources they’d be willing to share, I’d be incredibly grateful! Let’s keep the conversation going and help each other achieve those zero feed-in goals. 