ONEp1 - P1 Smart Meter Dongle with 4-Port Multiplexer for Solar Surplus Management

Hi everyone,

I’d like to share ONEp1, a P1 smart meter dongle with Home Assistant integration that I’ve been developing.

What is ONEp1?

ONEp1 is a hardware dongle that connects to your Dutch/Belgian P1 smart meter port and splits the P1 signal across 4 output ports. Each port sends a modified P1 telegram to connected devices (EV chargers, home batteries, heat pumps, boilers), allowing them to work together based on solar surplus using a smart waterfall distribution system.

Home Assistant Integration

We’ve built a custom HACS integration that provides:

  • Real-time power sensors — consumption and production (kW, updates every 10s)
  • Energy dashboard compatible — total consumption/production (kWh) + gas (m³)
  • 4 channel status sensors — with attributes like priority, max power, reaction time
  • onep1.set_channel service — control all channel settings from automations
  • HA control toggle — exclusive control switch between HA and the ONEp1 dashboard

Installation

Available via HACS (custom repository): Michiellenselink/ha-onep1

Or download directly from the ONEp1 dashboard.

Use Cases

  • Prioritize your heat pump in winter, EV charger in summer
  • Turn off devices when nobody’s home
  • Adjust max power based on weather forecast
  • Control battery charge/discharge based on energy prices

Links

Happy to answer any questions!

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