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Webinar: DC-Coupled Energy Storage ... Nuvation Energy, Maximo Solar, and the California Energy Storage Alliance (CESA) take a closer look at the differences between AC- and DC-coupled energy storage behind the meter ... Viewers will gain a better understanding of these architectures, plus insights that will help them choose an approach for their own solar and storage microgrid project.   ... ... This webinar explores: ... The architecture and engineering differences between AC- and DC-coupled solar and storage. ... The opportunities and challenges for islanded microgrids in California markets. ... A project example of a DC-coupled microgrid in Puerto Rico.

Webinar: Battery Management System Impacts on Energy Storage ... Battery management systems impact the utility, effectiveness, and life of an energy storage system ... Passive balancing is less expensive than active balancing, but weaker cells or modules may need to be replaced near the end of the ESS’s lifespan ... Active balancing transfers energy from stronger to weaker cells, but at a higher system cost and design complexity. ... ... System down time is associated with both approaches and carries such a high opportunity cost that innovations in this area may be of greater importance than the type of balancing being employed. ... Nuvation Energy CEO Michael Worry explores the current state of the art in battery cell balancing, and how BMS innovations will impact the future of stationary energy storage. ... This webinar will focus on the following key topics: ... A stationary ESS orientation on battery management ... Understanding balancing-related down time ... Comparing active and passive balancing ... Innovations in battery management.

Energy Storage Designs that Maximize Supply Chain Flexibility ... Supply chain challenges will continue to affect the energy storage industry for the foreseeable future ... Lead times and costs have become increasingly unpredictable, which adds project risk ... Emerging technologies can also impact product design decisions ... In response to these risks and opportunities, energy storage system developers have begun creating supply chain agnostic ESS designs to maintain competitiveness in this rapidly changing industry. ... ... Joe O’Connor, Director of ESS Solutions at Nuvation Energy, examines ways ESS developers are reducing their project and business-risk through modular approaches to ESS design that anticipate supply chain challenges and innovation opportunities..

... When designing a battery management system, Nuvation’s fourth-generation battery management system and first off-the-shelf BMS, our goal was to create a set of modules that could be connected to the battery pack in different configurations to support a wide range of battery topologies with different chemistries, voltages, and capacities ... Our industry research and consultations with customers revealed three main market verticals where such a configurable BMS was of greatest interest to manufacturers: ... Specialty Vehicles – Battery powered traction systems and subsystems ... Telecom Power Backup – Data centers and telecom towers ... Grid Energy Storage – Micro grid, solar, wind, etc. ... While not every target battery deployment we encounter fits neatly into one of these categories, this matrix enables one to evaluate the Nuvation BMS in terms of its suitability to meet the full range of its target battery topologies. ... Battery Pack Scalability ... A battery pack is typically scaled in one or both of two directions: vertically and horizontally ... Scaling vertically involves stacking battery cells in series to increase pack voltage ... Scaling horizontally involves connecting multiple stacks of cells in parallel to create greater capacity at the same pack voltage ... Very large systems usually require the pack to scale both vertically and horizontally to deliver high voltage and high capacity. ... Returning to our matrix of battery pack configurations, we can summarize typical scalability needs as follows: ... For each battery stack, Nuvation's BMS has been partitioned into three distinct modules that are used as the building blocks of complete system. ... Stack Controller – performs all processing required to manage a single stack of cells ... Cell Interface – provides the electrical interface to a group of 12-16 battery cells ... Power Interface – powers the BMS, measures high voltages and large currents, and provides the electrical interface to high-current switching devices ... A Grid Battery Controller manages multiple stacks as a single unified battery' ... TopologiesSeparating functionality into these distinct modules allows Nuvation's BMS to scale to support a wide range of topologies ... Multiple Cell Interfaces are connected together in a daisy-chain that increases in height as pack voltage increases ... This daisy-chain is connected to a single Stack Controller that manages all cells in the chain ... Multiple Stack Controllers can be connected together to support large packs with many stacks in parallel ... The Power Interface isolates high-voltage and high-current components of the stack physically and electrically from the other modules ... It can also power the BMS directly from the battery stack, eliminating the need for any external power supplies.Nuvation's BMS is available in multiple variants that support a wide range of stack voltages ... In future posts we will examine in more detail how we can use these three modules in various configurations to meet the voltage and capacity requirements of different pack topologies..

... What makes an ideal battery management system? The first thing that should come to mind is safety ... There are many videos and articles out there that show lithium-based batteries venting and/or bursting into flames when pushed past their operating limits ... A BMS solution must prevent the battery pack from entering into an unsafe condition ... But safety is only the beginning of the story ... Users also want to maximize the life of their battery pack, and try to maintain the capacity of the battery pack as it ages ... This is where the idea of an “ideal” BMS solution can start to be defined. ... The ideal BMS solution provides accurate fuel gauging, and cell balancing to ensure that a battery back is completely empty or completely full ... There are two main design challenges to create the ideal BMS solution: ... Designing the internal battery pack topology to allow for monitoring of each cell. ... Including a mechanism for the BMS to balance the cells. ... There are three main topologies for cells in a battery pack: ... Battery Pack Topologies ... The simplest topology that allows for individual cell monitoring is a single string of series-connected battery cells ... A more complicated topology is necessary when the capacity of a battery pack needs to increase but the overall voltage needs to remain the same ... This requires a parallel connection of battery cells ... If the parallel connection occurs at the per-cell level, an approximation is made that each cell in the parallel string contributes equally to the overall health of the parallel string ... This approximation has the undesirable consequence of reducing the accuracy of the BMS ...  A parallel connection at the total pack voltage is better, as it allows the BMS to read the state of each individual cell ... It also opens the door for limp-home modes of operation ... (More on that later!) ... Just as there are multiple cell topologies, there are also multiple mechanisms for cell balancing ... Cell balancing brings each cell into alignment and ensures that each cell within the battery pack has equal state of charge (SoC) ... The Society of Automotive Engineers released a whitepaper in 2001 that describes different cell balancing solutions shown below: ... Cell balancing methods ... The simplest method to modify the level of charge of a battery cell is to apply a load to that specific cell ... This will lower the level of charge of highly charged cells to match the average level of charge ... This balancing method will provide the ideal BMS with a mechanism to ensure that the battery pack can be fully charged ... However, it doesn’t necessarily allow for the battery to be completely discharged in a useful way ... An active cell balancing method such as charge shuttling using a switched capacitor or energy conversion using a transformer allow cells nearing their end of charge level to be charged with excess energy contained in other cells still in their range of operation ... Refer to Nuvation’s recent article about cell balancing for further detail. ... Thus, to overcome the two previously mentioned BMS design challenges, it’s necessary to: ... Use a series-connected cell topology or use parallel-connected strings of series-connected cells to ensure accurate cell monitoring. ... Implement an active balancing method to allow increasing and decreasing SoC of each cell to ensure balance is achieved and maintained from completely full to completely empty. ... Resource: A Review of Cell Equalization Methods for Lithium Ion and Lithium Polymer Battery Systems.