This chapter describes the general context of HEMS to §14a EnWG, regulatory requirements and more detailed descriptions of the handling and fulfillment of limitations for different HEMS configurations.

§14a-compliant steering is possible for heat pumps that offer SG Ready communication over Modus or support the EEBus use cases OHPCF (Optimization of Self Consumption by Heat Pump Compressor Flexibility) and LPC (Limitation of Power Consumption). Connecting and steering heat pumps via IO devices is not supported in the context of §14a. For specific manufacturers and models, refer to the Supported assets list (SAL).

For systems with only one EV charger, the LPC signal is directly applied to that asset. The charge mode does not change during or after the LPC signal, but the maximum possible charging power is equal to the related limit.

In program charge mode, the charging power after an LPC limit might be higher than usual to achieve the charging target.

The user can plug or unplug the EV or change the charge mode as usual without any impact from the LPC signal. Only the maximum charge power remains due to the active LPC limit. The charge power might be slightly below the LPC limit since EV chargers only accept discrete charger powers. When the EV reaches the full state of charge or the charge mode achieves its charging target, the EV charging stops, regardless of whether an LPC limit is active or not.

If the LPC limit is below the minimum charge power of the EV charger, then the charging stops while the limit is active. In this case, the 8-minute lock safety feature (see Energy Optimizer feature description) keeps the EV from resuming charging for 8 minutes.

For systems with only a heat pump with the EEBus LPC use case, the LPC signal from the Steuerbox is directly forwarded to the LPC use case of the heat pump. The internal control of the heat pump manages the adjustment of the power consumption. The OHPCF use case is suspended when the LPC limit is active.

For SG Ready heat pumps, the LPC signal is mapped to SG Ready Mode 1. That is, the power consumption of the heat pump is stopped completely.

In such a system, the LPC signal is set as a limitation for the maximum charge power of the battery.

Same as with a battery only. However, for the maximum charge limit, the PV production power is taken into account.

The total consumption limit is applied to the group of these assets. The current PV production power is taken into account for the total consumption limit. If the consumption of battery and/or EVCS is larger than the limit, then the asset with lower priority gets limited first. To ensure compliance in all situations and at all times, the battery power cannot be used to compensate in the event of a consumption limitation due to technical constraints of the interface between battery and EMS. If the EVCS does get limited by the EMS, the behavior as described for the single-asset EVCS above applies.

Same as for PV+Battery+EVCS. If the HP gets limited by the EMS, the behavior as described for the single-asset HP above applies.

Same as for PV+Battery+EVCS. The asset to be limited first is reverse order of priority of PV surplus usage. To ensure compliance in all situations and at all times, the battery power cannot be used to compensate in the event of a consumption limitation due to technical constraints of the interface between battery and EMS. If the EVCS does get limited, the behavior as described for the single-asset EVCS above applies. If the HP gets limited by the EMS, the behavior as described for the single-asset HP above applies.

Same as PV+Battery+EVCS. The asset to be limited first is the reverse order of priority of PV surplus usage. To ensure compliance in all situations and at all times, the battery power cannot be used to compensate in the event of a consumption limitation due to technical constraints of the interface between battery and EMS. If an EVCS does get limited by the EMS, the behavior as described for the single-asset EVCS above applies.