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Using the Heat Pump Function on Solis Hybrid Inverters
(12 kW and Above)
Overview:
As Europe accelerates its transition toward clean and efficient heating solutions, heat pumps are rapidly becoming the preferred alternative to traditional gas or oil boilers. With high efficiency (COP > 3) and the growing availability of low-cost, renewable electricity—especially from solar PV—integrating heat pumps with hybrid inverters offers exceptional economic and environmental benefits.
To support this transition, Solis hybrid inverters (12 kW and above) now include a dedicated Heat Pump Function, enabling seamless communication with SG-Ready compatible heat pumps. This guide explains how the feature works and how to set it up.
IMPORTANT: Please ensure the inverter is running the latest DSP and HMI, and HMI_LCD firmware versions. LCD-based heat-pump control is only available when the HMI_LCD module has been updated to the most recent firmware.
Please note that Solis provides only the inverter-side connection. For wiring and configuration on the heat-pump side, customers must consult the heat-pump installer.
1. Why Use the Heat Pump Function?
Europe’s fluctuating electricity prices and increasing PV penetration make it ideal to use surplus solar energy for heating.
SG-Ready, a standardized interface, allows heat pumps to respond to external control signals. With Solis inverters, your heat pump can automatically operate in its most efficient mode when:
- PV generation is high
- Battery charge level is sufficiently high
The system converts inexpensive energy into stored thermal energy (e.g., hot water tanks or underfloor heating) to reduce reliance on expensive grid power.
2. Compatible Solis Hybrid Inverters
The Heat Pump Function is supported on the following Solis models:
S6-EH1P(3–8)K-L-PLUS / S6-EH1P(3–10)K-L-PLUS (21A)
S6-EH1P(9.9–18)K03-NV-YD-L
S6-EH3P(8–18)K02-NV-YD-L
S6-EH3P(12–20)K-H
S6-EH3P(5–10)K-H / S6-EH3P(5–12)K-H (21A)
S6-EH3P(5–10)K2-H / S6-EH3P(5–10)K2-H (21A)
S6-EH3P(29.9–50)K-H / S6-EH3P(29.9–60)K-H (21A)
3. How the Heat Pump Function Works
3.1 System Wiring Overview
Your SG-Ready heat pump connects directly to the inverter’s dedicated control terminals.
For wiring diagrams, refer to the installation manual specific to your inverter model.
3.2 Communication Principles
The inverter controls the heat pump using dry contacts (VCC-BIT1 and VCC-BIT2), which correspond to the four SG-Ready modes:
Mode | SG-Ready Meaning | BIT1 | BIT2 |
Mode 1 | OFF | 1 (Closed) | 0 (Open) |
Mode 2 | Normal | 0 (Open) | 0 (Open) |
Mode 3 | Enhanced | 0 (Open) | 1 (Closed) |
Mode 4 | ON | 1 (Closed) | 1 (Closed) |
Solis inverters use Mode 2 and Mode 3 for standard operation, with Mode 3 serving as the enhanced or “boost” mode.
3.3 Control Modes
You can choose between three control strategies:
A. Manual Mode
The user manually activates or deactivates Enhanced Mode.
- Switch ON → Enhanced Mode
- Switch OFF → Normal Mode
B. Schedule Mode
Enhanced Mode operates according to a weekly schedule programmed by the user.
- Up to six time periods per day (Monday–Sunday)
- Outside these periods, the heat pump returns to Normal Mode
C. Smart Mode
The inverter intelligently activates Enhanced Mode based on real-time conditions such as battery status and PV surplus.
Activation Requirements (all must be met):
- Battery SOC ≥ Enable SOC
- Grid feed-in ≥ Enable Power
Deactivation (any condition triggers shutdown):
- Battery SOC ≤ Disable SOC
- Grid feed-in ≤ Disable Power
Minimum Runtime After Startup:
- Default: 10 minutes
- Adjustable: 5–60 minutes (5-minute increments)
4. Parameter Settings
Battery SOC/Voltage Thresholds
Parameter | Default | Range |
Enable SOC / Voltage | 90% / 55 V | (Overdischarge SOC +5%) → 100% / 42–59.5 V |
Disable SOC / Voltage | 70% / 55 V | Overdischarge SOC → (Enable SOC – 5%) / 40–57.5 V |
Grid Feed-In Power Thresholds
Parameter | Default | Range |
Enable Power | 2000 W | 100 W – 1000 kW |
Disable Power | –500 W | –500 W – 10 kW |
Note:
Positive power = exporting to grid
Negative power = importing from grid
5. How to Access the Settings
You can configure the Heat Pump Function using either the SolisCloud App or directly on the inverter LCD.
SolisCloud App
Navigate to:
Inverter Control → More Functions → Heat Pump Setting
Inverter LCD Menu
Navigate to:
System Setting → More Functions → Heat Pump Setting
Conclusion
With the new Heat Pump Function, Solis hybrid inverters provide an intelligent and highly efficient way to integrate PV generation with modern heating systems. By leveraging SG-Ready communication, users can maximise self-consumption, reduce energy bills, and contribute to carbon-neutral living.
If you require additional support, please contact Solis technical service or refer to the detailed user manual for your specific inverter model.
