Sungrow PowerKeeper

Making use of surplus photovoltaic energy, reducing demand peaks and maintaining selected loads during a grid outage are some of the main energy challenges faced by businesses.

Sungrow PowerKeeper is a modular energy storage solution for commercial and industrial applications. It combines the ST050-250CF batteries, the three-phase Sungrow SH125CX hybrid inverter and an energy management and communication system based on a Logger and iSolarCloud.

The platform supports system configurations ranging from 49.9 kWh to 249.6 kWh and can be expanded to approximately 1 MWh, adapting to projects with different power, backup duration and consumption requirements.

What is Sungrow PowerKeeper?

PowerKeeper is a modular BESS designed to store electrical energy and use it later when it is more beneficial for the installation.

It can help businesses to:

• Store surplus energy generated by a photovoltaic installation.
• Increase self-consumption.
• Reduce specific demand peaks.
• Shift consumption to more favourable periods.
• Provide backup power for previously selected loads.
• Gradually expand the system’s storage capacity.

The solution mainly consists of the modular ST050-250CF batteries, the SH125CX hybrid inverter, a compatible Logger and the iSolarCloud monitoring platform.

DC-coupled architecture with the SH125CX hybrid inverter

PowerKeeper uses a direct-current-coupled or DC-coupled architecture.

In this configuration, both the photovoltaic modules and the batteries are connected to the Sungrow SH125CX hybrid inverter. The inverter manages solar generation, battery charging and discharging, load supply and energy exchange with the grid.

This architecture integrates photovoltaic generation and energy storage into a single solution. It can be used in new installations and, following the corresponding technical assessment, in certain expansion or retrofit projects.

The feasibility of each installation must be assessed by considering the existing electrical layout, photovoltaic capacity, consumption profile and intended operating strategy.

Sungrow PowerKeeper configurations

PowerKeeper is based on 12.48 kWh battery packs and offers standard configurations ranging from 49.9 to 249.6 kWh.

Configuration	Capacity
ST050CF	49.9 kWh
ST062CF	62.4 kWh
ST075CF	74.9 kWh
ST100CF	99.8 kWh
ST150CF	149.8 kWh
ST200CF	199.7 kWh
ST250CF	249.6 kWh

The battery packs operate at a nominal charging and discharging rate of 0.5P. This makes it possible to design configurations with an approximate duration of two hours when the system operates at its nominal power.

The effective duration will depend on the required power, state of charge, temperature, auxiliary consumption, battery degradation and the limits configured within the system.

Scalability up to approximately 1 MWh

The ST250CF configuration provides 249.6 kWh through four 62.4 kWh stacks, each consisting of five battery packs.

For projects requiring greater energy capacity, Sungrow offers optional combiner boxes that allow several clusters to be connected in parallel. In this way, PowerKeeper can reach approximately 1,000 kWh, equivalent to 1 MWh.

The platform is designed for solutions with approximate durations of between 2 and 8 hours. However, the final capacity, power and backup duration must be individually validated for each project.

The Sungrow SH125CX hybrid inverter

The SH125CX is a 125 kW three-phase hybrid inverter developed for commercial and industrial applications.

The inverter can simultaneously manage photovoltaic generation, energy storage, the grid connection and a backup output.

Its main characteristics include:

• Nominal AC power: 125 kW.
• Maximum photovoltaic input power: 250 kWp.
• Number of MPPTs: 10.
• Maximum charging and discharging power: 125 kW.
• Declared maximum efficiency: 98.6%.
• Protection rating: IP66.
• Corrosion resistance rating: C5.

The ability to accommodate up to 250 kWp of photovoltaic power makes it possible to design installations with a high DC/AC ratio, provided that the electrical and design limits established by the manufacturer are respected.

Backup power for essential loads

The SH125CX supports automatic switching between grid-connected operation and backup mode, with a declared switching time of less than 10 milliseconds and a nominal backup power of 125 kW.

This function can be used to maintain previously selected loads, such as:

• Cold-storage rooms and refrigeration systems.
• Servers and IT equipment.
• Security and communication systems.
• Essential lighting.
• Auxiliary equipment.
• Selected production processes.

The presence of a backup output does not mean that an industrial facility can continue operating in its entirety during a power outage.

The design must consider the simultaneous power demand of the loads, the starting currents of motors and compressors, the energy available in the batteries and the required backup duration.

LFP batteries and system safety

PowerKeeper uses lithium iron phosphate, or LFP, batteries. This technology is widely used in stationary energy storage due to its thermal stability and suitability for applications involving frequent cycling.

The system incorporates several safety and monitoring measures, including:

• Protection against thermal propagation at battery-pack level.
• Smoke sensor.
• Aerosol fire suppression system.
• Pressure relief valve.
• Voltage and current monitoring.
• Temperature monitoring.

These measures must be complemented by compliance with the applicable regulations, safety distances, ventilation requirements and fire-protection measures established for each installation.

Environmental protection and outdoor installation

PowerKeeper stacks feature IP66 protection and a C5-M corrosion resistance rating. These characteristics facilitate their installation in commercial and industrial environments exposed to demanding environmental conditions.

The system uses forced-air cooling and is designed for floor-mounted installation.

The final installation location must ensure:

• Sufficient ventilation.
• Maintenance access.
• Adequate load-bearing capacity.
• Protection against impacts.
• Proper drainage.
• Compliance with the required safety distances.
• Protection against flood risks.
• Compliance with fire-protection requirements.

The 49.9 kWh stack is supplied pre-assembled to facilitate delivery and installation. Each battery pack has a nominal capacity of 12.48 kWh and a maximum weight of 90 kg.

System expansion and active balancing

PowerKeeper incorporates active balancing at module level.

This function can facilitate future expansions and certain replacement operations by helping to compensate for energy differences between modules.

Any expansion must be carried out in accordance with the manufacturer’s official procedures and after verifying:

• Compatibility between different versions.
• The state of health of the modules.
• The state of charge.
• The installed firmware.
• The age of the batteries.
• The warranty conditions.
• The limitations of the existing system design.

The modular design therefore facilitates the future development of the system, but it should not be interpreted as allowing automatic expansion without prior technical validation.

Monitoring through iSolarCloud

The Logger collects information from the inverter, batteries and metering equipment and integrates it into the iSolarCloud platform.

The platform can be used to monitor information such as:

• Photovoltaic generation.
• Installation consumption.
• Battery state of charge.
• Charging and discharging power.
• Alarms and system incidents.
• Overall system operation.

Depending on the Logger, firmware, country and selected configuration, remote updating, diagnostics, meter integration and communication with external EMS platforms may also be available.

Main applications of Sungrow PowerKeeper

Increasing photovoltaic self-consumption

The battery stores solar energy that is not consumed immediately and makes it available when the photovoltaic installation stops generating or cannot fully cover demand.

This increases the use of solar generation and reduces the amount of electricity purchased from the grid.

Reducing demand peaks

PowerKeeper can discharge energy when consumption reaches a previously configured limit.

This strategy, known as peak shaving, can reduce the maximum power drawn from the grid and limit certain costs associated with consumption peaks.

Energy shifting

Businesses operating late in the day or at night can store part of their daytime photovoltaic generation and use it later.

This application can be particularly beneficial for facilities with refrigeration, air-conditioning, night-time lighting or continuous production processes.

Backup power

When combined with the SH125CX, PowerKeeper can maintain selected loads during a grid outage.

The available backup duration will depend on the installed capacity, battery state of charge and the power demand of the equipment connected to the backup output.

Electric vehicle charging

Energy storage can help reduce the power drawn from the grid when several vehicles are charging simultaneously and enable greater use of surplus photovoltaic energy.

Compatibility with the chargers and the energy management system must be specifically assessed for each project.

How to size a Sungrow PowerKeeper system

Battery capacity should not be selected solely on the basis of the installed photovoltaic power.

To size the system correctly, the following factors should be assessed as a minimum:

1. The hourly consumption profile.
2. Actual or estimated photovoltaic generation.
3. The volume and timing of surplus energy.
4. Maximum power demand.
5. The charging and discharging strategy.
6. The loads requiring backup power.
7. The required backup duration.
8. The installation conditions.
9. Plans for future system expansion.

An oversized battery can unnecessarily increase the initial investment. A configuration that is too small or has insufficient power may not be able to absorb the available surplus energy or cover the expected demand peaks.

For this reason, each project must be assessed using real data or estimates that are sufficiently representative of the installation’s operating conditions.