Solar and Wind Power Firming

Utilities are challenged with an increasing amount of solar and wind generation connecting into electricity grids, as these distributed energy resources are variable and intermittent. Power fluctuations can yield overall lower power predictability and quality of power generation, which is of particular issue when there are sensitive loads on circuits that cannot tolerate frequent fluctuations in voltage and frequency.

Worldwide, billions of dollars in grid infrastructure investment will be required to enable increasing solar and wind grid interconnection. Energy storage is a valuable strategy to improving the overall firmness, dispatchability, and predictability of renewable generation, with potential to defer T&D upgrade.

Power Firming

Renewable power output can drop by half within seconds. Even with meticulous interconnection planning, distribution and sub-transmission feeders can experience voltage instabilities, especially on long lines and on feeders where loads fluctuate and where renewable resources continue to be deployed.

By providing near real time solar and wind firming, the ultracapacitor (supercapacitor) grid energy system responds to the changing power flow to increase the general stability of the grid. Ultracapacitors mitigate variations inherent to solar and wind generation, thereby adding predictability to delivered power quality.

Ultracapacitor PV Smoothing

Example System Architecture: DC Coupled Active Paralleling


Solar + Storage, Wind + Storage

The cost of energy generation by solar and wind is rapidly reaching parity with traditional generation resources and in some regions is already lower. As these renewable resources are not inherently dispatchable, Maxwell ultracapacitor energy storage delivers power services (response time in cycles for durations into minutes) as a stand-alone grid storage asset.

When combining with Li-ion or other storage technology, storage times can be extended to multi-hour, providing operators with the greatest ability to capture multiple revenue streams. Because ultracapacitors are high peak current devices with 100% depth of discharge capability, there is a significant reduction in charge-discharge rate on the battery, which leads to longer battery lifetime.

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  • Response time: Maxwell ultracapacitor systems can be commanded to respond at full power in the cycles timeframe.
  • Footprint: The high power performance of ultracapacitors enables significant reduction reduction in storage system footprint versus battery systems for high peak power applications.
  • Long operating life*: Maxwell ultracapacitor systems typically provide a 12 to 15-year lifetime with no replacement cycles. Ultracapacitors are electrostatic devices designed to be repeatedly charged and discharged in full cycles or micro-cycles. Maxwell’s ultracapacitors have demonstrated over 1 million benchmark charge-discharges.
  • Capex reduction: Ultracapacitors are electrostatic devices that do not need to be 1-5x oversized to meet power requirements. In many cases, minimal to no balance of plant cooling is required because the devices have a wider operating temperature window and are not as prone to ESR rise (heating) as batteries.
  • Opex reduction: Maxwell ultracapacitor systems act as a buffer on the battery to mitigate degradation caused by heating. This preserves battery lifetime and reduces the number of battery replacement cycles.
*Results may vary. Additional terms and conditions, including the limited warranty, apply at the time of purchase. See the warranty details and datasheet for applicable operating and use requirements.

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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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