Sunstack™ was specifically designed to optimize solar capture and delivery. The Sunstack system architecture unites batteries and PV on the same side of the DC bus in order to take advantage of higher PV-to-inverter ratios, maximize solar yield, and simplify the interconnection process.

Sunstack includes all power conversion and controls needed to send solar energy to the grid or to store it for delivery later. Sunstack incorporates more than 14 years of design and deployment experience.


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Product Overview


  • DC-coupled system architecture
  • Co-located and distributed across solar fields
  • PV-specific dispatch algorithms
  • Total system safety


  • 500 kW DC/DC converters + solar PV inverter


  • 2 MW – 500+ MW


  • 1 – 4 hours


  • Renewable Integration: DC-Coupled Solar + Storage


  • Power conversion: UL1741, IEEE519, IEEE1547
  • Battery Safety: UL1973, IEC62619, IEC61508
  • System Safety: UL9540
  • Fire Protection: NFPA 855

PV Optimized

Sunstack is pre-designed to work with leading solar power product manufacturers, providing flexibility in both battery component selection and solar system coupling.

Co-locating solar and storage assets affords several benefits over separately sited facilities:

  • Distribute batteries, converters, and inverters throughout the solar field to minimize cable runs and improve project efficiency.
  • Share the balance of system costs across assets and reduces total expenses.

energy storage software

Integrated Intelligence

Sunstack’s integrated digital intelligence is designed for the unique requirements of solar + storage applications, such as peak shifting and firm capacity delivery. Sunstack enables you to prioritize when to charge and discharge your storage system based on solar output and network demand with PV-specific modes, including scheduled dispatch, export limiting, and directed charging.

Co-locating also increases project returns and asset value by stacking additional grid services, such as frequency regulation and ramp rate control.

Total System Safety

Sunstack’s comprehensive safety features span its integrated hardware and software technology stack.

Designed to meet industry-leading safety standards, such as UL9540, UL9540A, and IEC compliance, Sunstack is equipped with fast-stop, incipient gas detection, deflagration panels and more. Safety is embedded throughout every level of Fluence OS, which continuously monitors, detects, and alerts operators to potential anomalies.

Curious about combining energy storage with solar power?

Check out our white paper on the economics and technical considerations of Solar + Storage.

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Safety embedded across system design.

Fluence designs complete energy storage products with safety integrated into every layer of system controls and hardware.

Multiple layers of redundancy

Fluence OS is layered on top of all subcomponents to ensure system safety and functionality while patented control algorithms monitor and provide control over projects.

Comprehensive real-time monitoring

Fluence OS provides up-to-the-second visibility of unit performance, and continuously monitors, detects, isolates and alerts operators to potential anomalies.


Learn about safety at Fluence

Hardware-enabled safety measures

Subsystems protect themselves in event of a fault or failure in another subsystem, with all components having undergone rigorous qualifications and certifications.

Robust Network and Cybersecurity Management

Our storage technology contributes to critical infrastructure around the globe. To protect our customers and their networks from malicious attacks, Fluence complies with industry leading cyber security practices.

We follow the National Institute for Standards and Technology (NIST) Cybersecurity Framework to incorporate the latest security features, including high grade, 256-bit encryption, enterprise-class network security and firewall protection, multifactor authentication, weekly vulnerability scanning, and more.


VPN remote site access with 256-bit encryption, multi-factor authentication, and enterprise-class network security software.

Secure, role-based user access and control to local systems with weekly vulnerability scanning and patching.

In Transit

High grade 256-bit encryption protects all data in transit from local systems to virtual private cloud (VPC).

Data transfer and connectivity with VPC takes place over secure, site-to-site VPN tunnels.

In the cloud

Secure, logically isolated cloud environment uses restrictive firewall and security group rules to limit connectivity within the VPC (i.e. deny-by-default).

All external access into cloud data center is via VPN, utilizing multifactor authentication.

The Fluence Technology Stack

The Fluence Tech Stack combines hardware, controls, software, and intelligence into an integrated foundation for safe and repeatable energy storage products that are tailored to your use case and application.

Fluence Cube

Modular, factory-built, standardized form factor delivers safe, scalable, cost-effective products configurable with the latest storage components.

Fluence OS

Fully integrated operations platform combines comprehensive controls, asset management, and system visibility across single sites or entire fleets.

Fluence IQ

AI-enabled digital platform to improve revenue generation, system decision-making, asset performance and operations.

It’s in our DNA.

Fluence understands how to optimize solar + storage and will work with you to design the energy storage solution for your needs.

Get started with our Sales team today.

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