Power Limitation

Sometimes the power usage of a heat pump needs to be reduced for various reasons. Either due to local power limitations, or to be able to navigate power tariffs set by utility (electric grid) provider. As an example from Sweden, by January 1, 2027, there is a requirement that all electricity grid companies must have introduced an impact tariff into their prices.

How does it work?

With the software in the NIBE heat pumps, it is possible to let the heat pump limit its consumed power. This means that the customer can avoid high power peaks when the tariff is at its most expensive and thus save money while helping the electricity grid. The heat pump can limit or completely switch off both the electric addition and the compressor to avoid the highest power peaks, this could be done down to the smallest system available immersion heater step. The indoor temperature, hot water and other comfort functions can be negatively affected when the function is active, which needs to be weighed against the monetary savings in each given case.

Alternative

Integrated load monitor

NIBE heat pumps are equipped with a simple form of integrated load monitor, which limits the power steps for the electric additional heat by calculating whether future power steps can be connected to the relevant phase without exceeding the current for the specified main fuse. If the current would exceed the specified main fuse, the power step is not permitted. The size of the property’s main fuse is specified in menu 7.1.9 - "Load monitor". Please consult the product manual for more information.

Load monitor with current sensor

When many power-consuming products are connected in the property at the same time as the compressor and/or the electric additional heat is operating, there is a risk of the property’s main fuses tripping. Many NIBE heat pumps are equipped with a load monitor that, with the help of a current sensor, controls the power steps for the electric additional heat by redistributing the power between the different phases or, alternatively, disengages the electric additional heat step-by-step if there is an overload in a phase.

If the overload remains despite the additional electric heat being disengaged, the compressor is limited and comfort will be reduced. Reconnection occurs when the other current consumption is reduced. The building’s phases can have different loads. If the compressor has been connected to a heavily loaded phase, there is a risk that the compressor output will be restricted, and the additional electric heat (on another phase) will operate longer than expected. This means that the complete systems savings will not be as expected. Please consult the product manual for more information or consult a skilled electrician.

Load limitation by AUX in

Limits the maximum allowed power consumption, level can be set by user in accordance with local regulation, to set level (for example 4.2kW) for the time the AUX in port is activated. Activation must be triggered from an external device, or for S-series, it can also be done by writing to the AUX register via Modbus TCP/IP.

Please note that a low set limitation will lead to comfort limitations, and in worst case risk for freezing or damages to the house.

The activation level and time is also logged to myUplink.

The default power limit is 4.2 kW, but it can be changed to a desired value in menu 7.4.2.

Load limitation by Schduling

With the scheduling function found in the S-series home screen, power limitation can be scheduled for times you think are appropriate, both based on the electricity contract and your own use. For example, if the electric car charges for a certain period during the night or the household often cooks at the same time, power limitation can be added to the heat pump during this time. Several different periods and power limitation levels could be set per day.

To activate power limitation, go to menu 6 “Scheduling” and create a new mode or edit an existing mode. Then select the “Power management” to be set by that mode and then do the scheduling of times.

Move the load by SG Ready via AUX

SG ready is a form of tariff control where the product can be influenced by another external device to control the system. An external device can monitor the peak power usage of the entire household and send a signal to the heat pump when the external device decides it is time to block, increase, reduce or work according to normal operation. SG ready can affect the indoor, hot water and/or pool temperature or simply block the additional heat and/or the compressor in the heat pump during certain times of the day.

Potential-free contact is connected to two inputs. Then “SG Ready A” and “SG Ready B” are selected in menu 7.4 “Selectable inputs/outputs”. In menu 4.2.3, you select which functions are to be influenced by SG Ready.