Energy-aware heat pump control using SG Ready
Hardware & Software
Problem
The off-grid backup system could not operate reliably during real grid outages and power failures.
When a grid loss occurred:
- The SolarEdge Backup system attempted to transition into off-grid mode
- At the same time, the heat pump was free to start according to its internal logic
- Compressor startup caused a high inrush power demand
- The inverter and battery could not supply this peak instantly
As a result:
- The off-grid transition failed or became unstable
- Inverter protection mechanisms were triggered
- Backup operation required manual intervention
To keep the system running during a power outage, the heat pump had to be manually enabled or disabled at the right moment.
In practice:
Off-grid operation during a grid failure depended on human action.
This led to:
- No reliable automatic behavior during outages
- High risk of incorrect timing under stress
- Reduced system resilience exactly when backup power was needed most
The setup worked under normal conditions, but failed precisely during grid failures, when reliability mattered the most.
Context
The installation consists of:
- Ground source heat pump: NIBE F1145 PC
- SolarEdge inverter with backup functionality
- SolarEdge Home Load Controller
- SolarEdge Home Backup Interface
- External contactor
- SG Ready input on the heat pump controller
Energy management decisions are made by the SolarEdge system based on PV production, grid availability, and backup state.
The SolarEdge Home Load Controller is not an autonomous controller. It acts as an execution device that switches its relay output according to commands issued by the SolarEdge Smart Energy logic.
The SolarEdge Home Backup Interface is responsible for grid isolation and islanding during power outages. Load control and load shedding are handled separately via the Home Load Controller.
Instead of switching power to the heat pump, this setup uses SG Ready as a permissive control interface. This allows the heat pump to remain powered while its operation is enabled or blocked in a controlled and supported way.
What is SG Ready?
SG Ready (Smart Grid Ready) is an intelligent tariff- and grid-aware control interface that allows external energy systems to influence the operation of a heat pump.
It enables an energy provider, PV system, or energy management system to:
- influence room temperature, domestic hot water (DHW), and optional pool heating,
- reduce energy costs,
- or block the compressor and/or auxiliary heater at specific times.
SG Ready is configured on the NIBE F1145 PC in menu 4.1.5 – “SG Ready” and requires physical connection to two potential-free digital inputs: SG Ready A and SG Ready B, assigned in menu 5.4 – “input/output configuration”.
SG Ready operating modes (NIBE F1145 PC)
The combination of the two SG Ready inputs defines four operating modes:
SG Ready Mode 1 – Blocked operation
(A: Closed, B: Open)
- SG Ready is active
- Compressor and auxiliary heater are blocked
- Used to prevent operation during grid outages or unsafe conditions
SG Ready Mode 2 – Normal operation
(A: Open, B: Open)
- SG Ready is inactive
- No external influence on the heat pump
- The system operates according to its internal control logic
SG Ready Mode 3 – Economy mode
(A: Open, B: Closed)
- SG Ready is active
- The system focuses on cost reduction
- Can use low energy tariffs or excess power from local sources (e.g. PV)
- System behavior can be adjusted in menu 4.1.5
SG Ready Mode 4 – Excess power mode
(A: Closed, B: Closed)
- SG Ready is active
- The system is allowed to operate at maximum capacity
- Intended for situations with very low energy prices or significant excess power
- System behavior can be adjusted in menu 4.1.5
(A = SG Ready A, B = SG Ready B)
SG Ready provides behavioral control, not power switching. The heat pump remains powered and makes internal decisions within the limits defined by the active SG Ready mode.
COSTS
Below is a realistic cost breakdown for this integration. Prices vary by country, installer, and availability.
Hardware
- SolarEdge Home Load Controller: ~€120
- Wiring & accessories: ~€0–€40
Labor (optional)
- Electrician / installer work (wiring + verification): typically 1–3 hours, depending on site complexity.
High-level solution
The solution is based on permission-based load control, not power switching.
- The heat pump and the SolarEdge Home Load Controller are physically connected using control wiring
- The SolarEdge Home Load Controller itself must be properly wired and powered to operate
- SolarEdge Smart Energy logic evaluates grid state, PV production, and backup conditions
- Based on these conditions, SolarEdge issues load control commands
- The Home Load Controller executes these commands by switching its relay output
- The relay drives an external contactor connected to the SG Ready input of the heat pump
- SG Ready determines whether the heat pump is allowed to operate
When a grid outage occurs, SG Ready permission is automatically removed. This prevents compressor startup during off-grid transitions and eliminates the need for manual intervention.
The heat pump remains powered but becomes a controlled, cooperative load within the backup system.
This is not a plug-and-play setup — correct wiring and configuration are required on both the SolarEdge and heat pump sides.
Outcome
After introducing SG Ready–based control using the SolarEdge Home Load Controller, the system now behaves predictably during real grid outages.
- Off-grid transitions are stable and repeatable
- The heat pump no longer starts during unsafe moments
- Backup operation works without manual intervention
- Startup power spikes no longer destabilize the inverter
- PV surplus is used only when conditions allow it
The backup system now works automatically and reliably, exactly when the grid is unavailable.
Unlock technical details (15€)
This paid section provides the exact configuration and wiring details required to reproduce this setup reliably.
It includes:
- Step-by-step NIBE F1145 PC configuration
- SG Ready enablement
- Digital input mapping
- Behavior selection for heating and DHW
- SolarEdge configuration
- Smart Energy / Home Load Controller settings
- Backup-related behavior and constraints
- Wiring diagrams
- Connections between the Home Load Controller, contactor, and SG Ready input
- Power and control wiring overview
- Real installation photos
- Controller wiring
- Contactors and connections
This is not theoretical documentation. All settings and diagrams are based on a working, field-tested installation.
If you want a backup-safe, SG Ready–based integration without trial and error, this section saves time, prevents mistakes, and avoids risky power-cut experiments.
Codes are sent by email after purchase. Valid for 7 days, up to 50 views, max 3 devices.