A BESS is a battery system that stores electrical energy and supplies it when needed. It increases self-consumption, reduces energy export to the grid, and supports load management.
For installers: Assess charging and discharging power, storage capacity, cycle life, round-trip efficiency (RTE), depth of discharge (DoD), and communication compatibility with the inverter or EMS.
Yes. The battery inverter capacity must not exceed the capacity of the solar PV system and, in all cases, must not exceed 30 kVA where no energy is exported from the batteries to the grid. (Source: HEDNO)
For installers: Confirm the intended operating mode (grid-connected without battery export or participating in an energy-offset scheme) before sizing the battery inverter.
Yes. The storage system absorbs surplus solar generation that would otherwise be curtailed, increasing the utilisation of the solar PV system.
For installers: The inverter/hybrid inverter, smart meter, and EMS must be properly coordinated to ensure that the battery operates within its specified limits.
In a DC-coupled system, the battery is connected on the DC side through a hybrid inverter. This involves fewer energy-conversion stages and provides higher overall efficiency, making it particularly suitable for new installations. In an AC-coupled system, the battery has its own inverter and is connected on the AC side, making it easier to add storage to an existing solar PV system without replacing the existing inverter.
For installers: For retrofitting an existing installation, an AC-coupled system is generally preferable. For a new project, a DC-coupled system usually provides higher overall efficiency.
The C-rate indicates the battery’s charging or discharging rate in relation to its capacity. For example, a C-rate of 0.5C for a 10 kWh battery corresponds to a power rating of 5 kW. It determines how quickly the battery can supply or absorb energy, which is particularly important in applications involving sudden load peaks.
For installers: When providing backup power for high-demand loads, such as pumps or compressors, check the maximum continuous C-rate rather than relying only on the peak rating.
LFP, or lithium iron phosphate, offers a longer service life, improved thermal stability and greater safety, although it has a slightly lower energy density. NMC has a higher energy density, allowing for a more compact system at the same storage capacity, but requires more careful thermal management. LFP is now the predominant battery chemistry used in residential and commercial stationary energy storage applications.
For installers: In areas with limited ventilation or stricter fire-protection requirements, LFP is generally the safer choice.
Backup capability allows the system to supply selected loads during a grid outage while operating temporarily in island mode. Black-start capability allows the system to start from a de-energised state without relying on an external power supply.
For installers: Backup operation requires a separate critical-loads distribution board and an automatic transfer switch (ATS). Confirm whether the inverter or BESS supports this functionality as standard or requires additional equipment.