Comergy heat-pump digital twin
power, PV & heat in one view
A physics-based simulation of a modulating groundwater heat pump (with summer free cooling), a 30 kWp rooftop PV array and a 20 kWh home battery — driven by real historical weather, running continuously day after day. The page brightens with the sun and goes dark at night.
Operating dashboards
SunSpec values
The PV inverter runs on its own Modbus/TCP slave, separate from the heat pump, exposed as a standard SunSpec map on the holding registers at base 40000 (common model 1 + inverter model 101). These are the live points a SunSpec scanner would read.
| Reg | Point | Description | Value | Unit | Raw | SF |
|---|
Battery registers
The home battery is exposed on its own Modbus/TCP slave. These are the live input registers (the same values are drawn in the scene above).
| Reg | Point | Description | Value | Unit | Raw |
|---|
Heat-pump details
The internal operating point of the modulating compressor and the day's temperature and heat-output trajectories.
Temperatures over the day
Heat output & COP
All values
Every instantaneous quantity at the current playback position — identical to the values served over REST and Modbus.
Electricity: consumption, PV & grid
Modbus register map
The twin runs a Modbus/TCP slave mirroring the heat-pump register map. Input registers (FC04) are read-only sensors; holding registers (FC03/06/16) are setpoints. (The PV inverter has its own separate SunSpec slave — see above.) Search all 1745 registers below.
| Reg | Type | Title | Value | Unit | Size | Raw |
|---|
The refrigeration cycle
A heat pump moves heat from a cold source to a warmer sink by cycling a refrigerant through four stages. It does not create heat — it relocates it, which is why it can deliver several kilowatts of heat per kilowatt of electricity.
Four stages, one continuous loop
The compressor raises the refrigerant's pressure, heating it well above the supply temperature your home needs. In the condenser it gives up that heat to the heating water and condenses to a liquid.
The expansion valve drops the pressure, chilling the refrigerant below the source temperature. In the evaporator it absorbs heat from the source — here ~12 °C well water — and boils back to a gas, ready to be compressed again.
Beyond the heat pump, the twin also models a 30 kWp PV array and a 20 kWh home battery. PV first covers the building's electricity, then charges the battery; only the surplus is exported to the grid. A shortfall is taken from the battery first, and only then imported from the grid — so self-consumption is maximised.
Hardware configuration
Choose a hardware + building package. The schematic and the entire simulation update to match the heat source, emitter type, capacity class and building. The default uses groundwater (well water, ~12 °C) as the source medium.
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Run parameters
These are the operator-tunable setpoints — the same levers exposed as writable Modbus holding registers on the real unit. Apply to re-simulate the day.
Weather & day selection
Pick a starting day and location. Outdoor temperatures, shortwave radiation (driving the PV model and the background brightness) and sunrise/sunset are pulled from open-meteo.com's archive, then the day is simulated at 1-minute resolution and replayed continuously from the dashboards above.