The Problem: A “Dumb” Boiler and Unused Solar
📖 Original post: 👉 https://community.home-assistant.io/t/909586
The article, titled "Turning a dumb water heater into a smart hot water battery using excess solar power with off-the-shelf components", showcases a smart and cost-effective way to upgrade a conventional electric water heater into a solar-powered hot water battery, improving the utilization of excess solar energy generated at home.
One of the key components in the setup is the IAMMETER WPC3700, a Wi-Fi power controller with built-in power monitoring and MQTT support. The user integrated this smart load controller into Home Assistant, enabling automatic on/off control of the water heater based on real-time solar surplus availability.
Key features used in this project:
- WPC3700 acts as a smart relay with current sensing, controlling the water heater load intelligently.
- Integrated seamlessly into Home Assistant via MQTT, without the need for any cloud services.
- The automation logic checks if solar power generation exceeds household consumption and switches on the heater only when excess energy is available.
- Helps convert the water heater into a thermal energy storage device (hot water battery), improving solar self-consumption.
Although the user employed a third-party smart meter to monitor overall solar generation and grid usage, the flexibility of IAMMETER’s open MQTT protocol makes it compatible with various systems, sensors, and platforms.
This project demonstrates how the WPC3700 can be used as a solar diverter alternative, especially for DIY enthusiasts and solar-powered households looking to optimize their energy usage with smart switching based on solar surplus.
Real Benefits Achieved:
By implementing this setup, the user successfully reduced grid export, increased solar self-consumption, and made smarter use of free solar energy. This aligns perfectly with the original mission of IAMMETER products — not just monitoring, but helping customers save electricity bills through intelligent control.
Smart Solar Surplus Control for Electric Water Heaters | IAMMETER
Power Your Heater with Solar Surplus and Save on Your Electricity Bill
