How to Choose a 2.5–5 MWh Containerized Energy Storage System
Selecting a containerized battery energy storage system involves more than comparing rated energy capacity. Project developers also need to consider rated power, available installation space, equipment weight and the operating requirements of the application.
The HLY-SLS liquid-cooled container energy storage system is available in four rated energy configurations: 2.5 MWh, 3.34 MWh, 4.18 MWh and 5 MWh. The range provides options for projects with different energy storage requirements while retaining a common container size.
Two details are particularly relevant when evaluating this system: the range of capacities available within the same external dimensions, and the relationship between rated energy, rated power and the stated charge-discharge rate.
Four Energy Capacities in One Container Format
The HLY-SLS series offers four configurations with the same listed external dimensions of 6,058 × 2,438 × 2,896 mm. Rated energy capacity ranges from 2.5 MWh to 5 MWh, allowing project teams to evaluate different storage capacities without changing the stated container dimensions.
| Model | Rated Energy | Rated Power | Approx. Weight |
|---|---|---|---|
| HLY-SLS41606Y2.5M | 2.5 MWh | 1.25 MW | 27 tonnes |
| HLY-SLS41608Y3.34M | 3.34 MWh | 1.7 MW | 33 tonnes |
| HLY-SLS41610Y4.18M | 4.18 MWh | 2.15 MW | 38 tonnes |
| HLY-SLS41612Y5M | 5 MWh | 2.5 MW | 43 tonnes |
Specifications are based on the HLY-SLS product datasheet. Confirm the final configuration and technical documentation for the project before ordering.
Having several capacity options in the same container format can simplify early-stage site planning. Developers can compare the storage capacity required for a project while working with a consistent external enclosure size.
However, the enclosure dimensions alone do not determine the full installation requirements. The listed weight varies from approximately 27 to 43 tonnes, depending on the model. Foundation loading, transport access, lifting arrangements, maintenance clearances and local installation requirements should therefore be checked against the selected configuration.
Which Capacity Is Appropriate for Your Project?
The selection should start with the project’s energy requirement and expected operating pattern.
A 2.5 MWh unit may suit a project with a lower storage capacity requirement or a phased deployment plan. The 3.34 MWh and 4.18 MWh configurations provide intermediate options. The 5 MWh model offers the highest rated energy capacity in this product range and has a corresponding rated power of 2.5 MW.
These figures are starting points for comparing configurations, not a substitute for system sizing. The appropriate choice depends on the required charging and discharging power, operating schedule, connection capacity, usable energy requirements and the number of operating cycles expected.
For multi-unit projects, the developer should also establish whether the planned system can be integrated with the selected power conversion system (PCS), energy management system and site control architecture. The product information states compatibility with mainstream PCS equipment and multiple communication protocols; the exact interface and protocol requirements should be confirmed during engineering.
Rated Power, 0.5C Operation and Energy Efficiency
The relationship between rated energy and rated power matters because the two specifications describe different aspects of a battery energy storage system.
Rated energy, expressed in megawatt-hours (MWh), indicates the system’s stated energy capacity. Rated power, expressed in megawatts (MW), indicates its stated charging or discharging power capability under the specified operating conditions.
For the HLY-SLS range, the rated charge-discharge rate is 0.5C. The model specifications pair 2.5 MWh with 1.25 MW, 3.34 MWh with 1.7 MW, 4.18 MWh with 2.15 MW, and 5 MWh with 2.5 MW. These combinations are approximately aligned with a two-hour nominal energy-to-power ratio.
That ratio is useful when making an initial comparison, but it should not be treated as a guarantee of usable discharge duration. Actual operating time depends on the permitted operating window, system losses, operating conditions, reserve requirements and the project’s control strategy.
The datasheet also lists energy efficiency of at least 92%. This is an important figure to review when estimating the energy returned by a storage system after charging. Before using it in a financial model or project guarantee, the buyer should confirm the measurement boundary, test conditions and whether the quoted figure is measured at the DC or AC system level.
For a realistic project evaluation, rated power and rated energy should be considered together. A capacity figure on its own does not establish whether a system can meet a site’s peak demand, dispatch schedule or grid-service requirements.
Key Technical Specifications
The HLY-SLS series uses lithium iron phosphate (LFP) battery cells, with the datasheet specifying 314 Ah / 3.2 V cells. Other listed system specifications include:
- Rated voltage: DC 1331.2 V
- Operating voltage range: DC 1123.2–1518.4 V
- Rated charge-discharge rate: 0.5C
- Listed energy efficiency: ≥92%
- Thermal management: Liquid cooling using a 50% ethylene glycol solution
- Ingress protection: IP55
These specifications should be reviewed alongside the applicable project requirements. In particular, the PCS voltage window, protection coordination, communication interfaces and local grid requirements need to be checked during system integration.
What to Confirm Before Requesting a Quotation
A useful request for quotation should provide more than a target MWh figure. To identify a suitable configuration, project owners should prepare the following information:
- Required energy capacity and power: Specify the target MWh and MW, along with the expected charging and discharging schedule.
- Installation conditions: Provide the site location, available footprint, access limitations and any relevant environmental conditions.
- Electrical and control interfaces: Identify PCS requirements, grid connection parameters, control-system interfaces and communication protocols.
- Performance assumptions: Clarify the required usable energy, efficiency measurement boundary, operating window and warranty or degradation requirements.
These details help suppliers assess whether a proposed configuration matches the project rather than simply matching a headline capacity.
A Practical Starting Point for Container ESS Selection
The HLY-SLS liquid-cooled container energy storage system provides four rated energy options from 2.5 MWh to 5 MWh within the same listed container dimensions. Its rated power configurations range from 1.25 MW to 2.5 MW, with a stated 0.5C charge-discharge rate and energy efficiency of at least 92%.
For developers comparing containerized battery energy storage systems, these specifications provide a clear basis for an initial assessment. The final model should be selected against the project’s power demand, required usable energy, site conditions and integration requirements.
Yue Laikai Energy Group can review the project’s capacity target, power requirement and installation conditions to help identify a suitable configuration and define the information needed for a technical proposal.