Hi everyone,
I know there are several similar projects out there, but I still wanted to share Zero-Grid, a project I’ve been working on. It’s an ESP32-based system that dynamically routes surplus solar power to a resistive heater (like a water heater or space heater) to keep grid import/export near zero. This is particularly useful in the Netherlands, where the net metering scheme (“salderingsregeling”) will end in 2027, making local consumption of solar energy increasingly important.
Features
- PID-controlled power routing - continuously adjusts heater power to keep grid import/export close to 0 W, with the ability to fine-tune PID parameters in real time from Home Assistant.
- DAC output (0–10 V) - drives an external voltage regulator to control heater power.
- Bypass relay - engages full power if solar surplus exceeds the heater’s max capacity
- Automatic operation - reacts multiple times per second to changes in solar production
- Manual mode - allows testing or calibration of heater load
- MQTT integration - receives power and voltage data from a smart meter or Home Assistant
- Temperature safety - stops routing power if a heater or enclosure temperature becomes unsafe