Maxwell Grid Energy Storage System

Engineered for fast response, high power applications in grids and microgrids

Energy storage systems are facilitating the modernization of electricity grids and are now a key distributed energy resource (DER) to ensure reliable delivery of reactive and active power given an evolving mix of traditional and renewable energy generation. As more solar and wind are interconnected, energy storage systems (ESS) must respond faster and cycle more frequently to ensure grid power quality and resiliency in a generation nameplate mix that includes growing amounts of utility scale wind and solar. Further, advanced energy storage systems are filling gaps in grid ancillary services as a result of continued global trends in the loss traditional sources including fossil based energy.

The provision of power-intense applications requires more advanced and optimized ESS architectures to achieve technical, cost and profitability targets.

Leveraging two decades of use in the grid, Maxwell ultracapacitor-based grid energy solutions deliver fast responding, high peak power grid storage utilizing field-proven energy delivery technologies and advanced utility grade control and communication systems.

Our highly scalable energy system is deployed either as an optimized battery-ultracapacitor energy storage system or as a stand-alone ultracapacitor system to deliver energy and power better, faster and for less than traditional battery storage systems. The system dispatches power and energy to the grid measured in cycle timeframes to minimize and eliminate costly transient grid events to serve the needs of mission critical grid and industrial applications. Maxwell’s advanced systems are deployed to stabilize frequency, provide voltage support, smooth renewable power output, provide synthetic inertia, bridging and ramping, and improve generator response.

System Building Blocks

Ultracapacitors (supercapacitors) are the core technology powering the system. Unlike electrochemical battery systems, which are typically oversized to mitigate lifetime degradation related to heating (I2R) during high peak power delivery and frequent cycling, ultracapacitors store charge electrostatically which allows them to be rapidly and frequently charged and discharged while maintaining lifetime and very high c-rate equivalency. Typical operating temperature range is from –40 to 65oC. With over 8 million devices deployed in utility grids, Maxwell’s proprietary core technology has withstood the test of utility deployments globally to deliver reliable, resilient and durable performance required for grid operations.


Grid Modules:
Ultracapacitor cells are combined into a series string and assembled into modules. The modules feature advanced voltage, temperature and cell balancing with an internal and external monitoring and communication system that is designed from the ground-up to ensure system reliability and long system-level life. Additionally, the module features Maxwell Technologies’ High Voltage Interlock Loop (M-HVIL™) to enable the advanced functionality of internal system fail-over, providing an additional level of safety to field assets.


Grid Energy Storage System:
Ultracapacitor modules are installed in standard 19'' rack systems combined with a communications gateway providing two-way communication for state of availability and state of health via Modbus TCP/IP or Process Field Net (Profinet) protocols.



The Maxwell Grid Energy Storage System is based on utility requirement-driven design expertise, with a critical eye on grid integration at the distribution, substation and transmission level. These systems are available from your preferred battery energy storage system provider or system integrator. Maxwell works directly with major utility equipment OEMs and your preferred suppliers to deliver optimized solutions based on specific technical project needs that are higher performance and lower cost than stand-alone battery energy storage.

Project Modeling

Maxwell offers industry leading lifetime prediction capability with our advanced ultracapacitor cell lifetime estimation tools based on over 3 million hours of product testing. With this foundation, Maxwell’s grid solutions team works hand-in-hand with stakeholders and uses state-of-the-art tools to model system dynamics when integrated in the power grid with traditional and renewable generation resources along with grid control systems. This provides the technical justification, financial justification and deep analysis required by the utility, public utility commissions, ratepayers and appropriate regulatory and governmental bodies.


Maxwell’s Grid Energy Storage System can be integrated and sited at utility distribution, substation, sub-transmission, fossil and renewable power plants, commercial or industrial sites, large microgrids, isolated microgrid/minigrid in remote areas, or utilized as a T&D grid support asset to provide grid energy storage.

Application Utility
Solar and Wind Power Firming
Mitigate msec-sec timeframe power fluctuations to ensure local power quality, especially on long feeders or with a high penetration of renewable energy. Enable interconnection of more renewable projects which would otherwise require costly infrastructure investment.
Maxwell ultracapacitors are deployed as a stand-alone asset or integrated with batteries to provide near real time frequency, voltage and power firming and smoothing in island mode. These devices meet the most demanding transient and pulsed power loads and provide the highest level of availability and reliability in support of utility microgrids, commercial and industrial microgrids, campuses and industrial parks, and critical assets including defense and military microgrids.
Voltage Sag Mitigation and UPS
In utility grids and microgrids, Maxwell ultracapacitors provide voltage, frequency and power stabilization in near real time. Fast responding, transient response capability mitigates deep and/or recurring power sags from cycles to minutes. In manufacturing and C&I facilities, ensure delivered power meets ANSI, CBEMA and SEMI standards for continuous operations and to mitigate risk of financial loss. Systems can be sited on utility side or customer side-of-meter and occupy a significantly smaller footprint providing faster response than alternative battery and generator solutions.
Primary Frequency Response
Renewables do not provide the necessary inertia and short circuit power to the power system. Maxwell ultracapacitors provide fast frequency response (FFR) as a stand-alone system or integrated with batteries. Fast, reliable cycles timeframe response for synthetic inertia can also be provided when integrating with SVC, STATCOM or as a replacement to SYNCON. Enable interconnection of assets such as PV and wind, stabilize voltage and frequency while replacing the system inertia deficit due to retired fossil and nuclear generation plants. Fast response to mitigate, in near real time, a decrease in generation, generation-load imbalance and unpredictable variations in demand.
Generator Bridging, Ramping, and Regulation
Maxwell ultracapacitors provide controlled ramp rates from cycles-to-seconds-to-minutes until generator ramp is complete. Reduce the need for idling resources and reduce fuel consumption. Fast responding energy storage to respond to an increase or decrease in generation (or load), to respond to markets or random, unpredictable variations in demand.
Hybrid Storage – Asset Optimization and Stacked Services
New levels of stacked functionality are now achieved by integrating traditional Li-ion and other battery chemistries with ultracapacitors. Capacity, peak load management, energy arbitrage, near real time voltage and frequency stabilization and regulation, FFR (fast frequency response), synthetic inertia, bridging and ramping can be combined in one system to maximize asset use, increase benefit-to-cost ratio and decrease payback period. Contact us and we will show you how.

Contact Us

Established in 1965, Maxwell Technologies has been a trusted supplier of high-tech energy solutions for customers worldwide. Over the past 20 years, system designers across industries have leveraged the power and speed of Maxwell’s ultracapacitor cell technology. Maxwell’s quality and proven field reliability is evidenced in the over 8 million devices provided to grid applications and 65 million ultracapacitors deployed in systems for automotive, heavy transportation, renewable energy and industrial applications.

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*Results may vary. Additional terms and conditions, including the limited warranty, apply at the time of purchase. See the warranty details and enclosed information for applicable operating and use requirements.