Table of Contents
Sungrow PowerStack 255CS-2H and 510CS-4H have the same nominal power of 125 kW in the European configurations compared here. Their main difference is battery energy: 257 versus 514 kWh. The larger system also changes the space and handling requirements. Choosing between them therefore starts with whether the business needs more energy at the same power rating, and whether the site can accommodate the corresponding enclosure.
This comparison covers the exact ST255CS-2H and ST510CS-4H designations in the EUR, Version 1 configurations. It helps a technical buyer check a proposal and prepare an integration brief. The supplied configuration, project documents, delivery arrangements for Ukraine and warranty terms require separate agreement. A product appearing in a catalogue does not establish that it is in stock.
Record the complete model designation
Commercial descriptions often shorten the name to PowerStack 255CS or PowerStack 510CS. Procurement requires more detail: the ST prefix, duration suffix and any regional ending must all be recorded. The enquiry, equipment schedule and documentation should identify the same model. A photograph of a similar cabinet does not verify its electrical ratings or configuration.
For example, ST510CS-4H and ST510CS-4H-AU cannot be treated as identical products. The Australian variant has a different designation and published power rating, so its specifications are excluded below. Likewise, the numbers 255 and 510 in the product names are not the nominal energy values. For this particular pair, those values are 257 and 514 kWh.
Ask the supplier to place the document revision, configuration and order contents beside the price. If a different version is proposed later, update the comparison. Describing equipment as equivalent does not automatically preserve the previous foundation, cabling, protection or backup calculations. Any substitution should identify which design decisions need another check.
Compare specifications on a consistent basis
The table applies to EUR, Version 1 for each model. Nominal energy refers to the battery, while nominal power and voltage refer to the grid-connected AC side. These are different measurement boundaries. The figures should not become a promise of usable energy at the business connection without a further calculation for that boundary.
| Parameter | ST255CS-2H | ST510CS-4H |
|---|---|---|
| Nominal AC power | 125 kW | 125 kW |
| Nominal battery energy | 257 kWh | 514 kWh |
| Nominal AC voltage | 400 V, 3P4L | 400 V, 3P4L |
| Width × height × depth | 1150 × 2450 × 1610 mm | 2152 × 2470 × 1610 mm |
| Weight | Up to 2900 kg | Up to 5300 kg |
| Enclosure protection | IP55 | IP55 |
| Corrosion protection | C5 | C5 |
| Cooling | Liquid cooling | Liquid cooling |
| Operating temperature | -30 to +50 °C, derating above +45 °C | -30 to +50 °C, derating above +45 °C |
Use the Sungrow PowerStack 255CS-2H and Sungrow PowerStack 510CS-4H product pages to discuss an order. Compare proposals dated on the same basis and covering clearly defined work. Do not insert a weight or protection rating from another revision into this table, even when the short product name matches.
What changes in the operating schedule
The additional battery energy of ST510CS-4H does not increase its nominal power relative to ST255CS-2H. If the main constraint is the instantaneous power required by the site, replacing the smaller model with the larger one does not resolve it by itself. If the requirement is to support an agreed load for longer, the extra energy becomes relevant to the calculation.
Prepare two versions of the same operating schedule, changing the available energy constraint for each configuration. Show when the system supplies loads, when it recharges and what reserve it retains for an interruption. The result should identify energy used, remaining reserve and any intervals that cannot be served. Use the same load data for both alternatives.
The 2H and 4H labels do not guarantee two or four hours of operation for any business. Nominal battery energy should not be equated with energy delivered to critical loads. The general method is covered in the handbook on choosing two-hour or four-hour energy storage. Here, the useful outcome is a check of these specific PowerStack configurations.
Check the space and delivery route
Enclosure dimensions allow an initial geometric comparison. The rectangular footprint of ST255CS-2H is 1.150 × 1.610 = 1.8515 m². For ST510CS-4H, it is 2.152 × 1.610 = 3.46472 m². The larger enclosure therefore occupies approximately 1.87 times the footprint while providing twice the nominal battery energy.
This calculation does not establish the required installation area. The layout must accommodate maintenance access, door opening, cable routes, drainage and safe placement requirements. A foundation cannot be ordered solely from width multiplied by depth. An enclosure fitting within a recess also does not establish that the location is suitable for operation or servicing.
Weights of up to 2900 and 5300 kg affect unloading arrangements and the assessment of the supporting structure. Check the transport route, lifting arrangement, equipment working area and permissible structural loads. Include these items before purchase: restricted access or an unsuitable base can change the practical choice even when the energy calculation favours one model.
Two ST255CS-2H systems or one ST510CS-4H
Adding the nominal figures gives two ST255CS-2H systems 2 × 257 = 514 kWh of battery energy. That equals one ST510CS-4H. However, the sum of the smaller systems' nominal power ratings is 250 kW, while the larger model is rated at 125 kW. Equal kilowatt-hours therefore do not make these arrangements interchangeable.
This is an arithmetic comparison, not an approved parallel connection design. Net power at the connection point depends on the project, network limits and control arrangement. If the business cannot use the additional power, a higher sum of equipment ratings does not create a practical benefit. The connection capacity should be checked before treating it as an advantage.
Two enclosures also require an appropriate arrangement of electrical connections, switching and coordinated control. Check what happens when one unit stops: without an agreed operating sequence, the arrangement cannot be described as guaranteed redundancy. Compare both architectures against the same task, including installation, servicing and any planned change in the site's demand.
The combined rectangular footprint of two smaller enclosures is 3.703 m², compared with approximately 3.465 m² for one larger enclosure. This excludes spacing. On a narrow site, arrangement may matter more than total area. Request alternative layouts showing actual access, doors and cable entries.
Define backup and existing solar integration
An integrated enclosure describes the factory product, but does not define the entire installation at the business. Separate the battery system from external switching, control, metering, cables and commissioning work. The proposal should identify included items and responsibility for everything else. This makes a price comparison meaningful when suppliers package the same model differently.
If operation during an outage is required, identify the critical loads, acceptable interruption and method of separating the backed-up circuits. Check starting conditions and recovery after battery discharge. None of the figures in the comparison table independently establishes uninterrupted operation of a production process. That outcome must be checked for the complete arrangement.
For a cold storage warehouse, prepare a critical-load register with dependencies and operating patterns to connect storage selection with the required equipment group.
For an existing solar installation, provide inverter models, the connection diagram, metering information and available controls. Establish which operating modes are supported with and without the grid. For a solar project that includes storage, start by agreeing the project design scope; integration of the particular PowerStack configuration must be defined for the individual site.
Operating conditions and acceptance
Both compared configurations use liquid cooling and specify the same operating temperature range, with power derating above +45 °C. Checking the minimum and maximum temperature alone is therefore insufficient. Summer operation requires an allowable power schedule for the actual installation conditions, rather than entering 125 kW unchanged in every interval of the model.
Acceptance should check the agreed charging and discharging modes, response to alarms and recovery after a shutdown. Record the energy measurement point, which auxiliary consumers are included and how operating logs are retained. These details create a consistent basis for evaluating either model and investigating a later difference between the design and measured performance.
A warranty period does not replace warranty conditions. Obtain the permitted operating modes, usage limits, service procedure and battery assessment criteria before deciding. Do not transfer a promotional period or terms from another market to the proposed supply. Identify who provides diagnostics and which owner actions are required to maintain the agreed conditions.
Keep the final comparison with the approved equipment schedule. Date each change in revision, unit quantity or load requirement. This gives procurement, engineering and installation teams the same baseline and exposes differences before equipment arrives.
Prepare a useful selection brief
Create a short site brief that allows both alternatives to be checked without changing the assumptions:
- Complete model designations, configurations, revisions and the number of systems in each proposal.
- Interval load data and a separate list of critical loads, including their starting requirements.
- Connection limits, available charging sources and details of the existing solar installation.
- A layout plan, access photographs and information about the base and maintenance access.
- Required operating modes, acceptance criteria, supply boundaries and service expectations.
These inputs help determine whether ST255CS-2H is sufficient, whether the additional energy of ST510CS-4H will be used, or whether another configuration is needed. Send the information through the relevant product page to agree the next step with ONG Solar. The output should be a checkable configuration with clear supply boundaries and a list of questions to resolve before ordering.