Revolutionizing Home Energy Storage: Key Trends and the Role of Bypass Technology in Enhancing Efficiency

2025-01-27
Bypass Technology is revolutionizing home energy storage systems by addressing key challenges like module imbalance, inefficient charging, and system degradation.

With the growing demand for clean and sustainable energy solutions, home energy storage systems are evolving rapidly. Bypass Technology has emerged as a game-changer in enhancing the efficiency, reliability, and longevity of these systems. 


Trends in Home Energy Storage Technology and Products


  1. High Capacity and Modularity
    Home energy storage batteries are evolving toward higher capacities to meet increasing household electricity demands. Additionally, modular battery systems allow users to flexibly expand capacity according to their needs.
  2. Integration and All-in-One Design
    Currently, most home energy storage systems are split-type, but future trends point toward integrated products that combine batteries and inverters into a single unit. This shift simplifies installation, enhances system compatibility, and improves reliability.
  3. Smart Management
    With the development of smart homes and the Internet of Things (IoT), home energy storage systems will incorporate more advanced Battery Management Systems (BMS). These systems will utilize data analytics and artificial intelligence to optimize energy use and intelligently schedule charging and discharging based on consumption patterns and grid conditions.
  4. Recyclability and Sustainability
    Future energy storage batteries will prioritize recyclability to reduce environmental impact and increase recycling efficiency. Additionally, some systems may adopt second-life batteries from electric vehicles for enhanced sustainability.


Master-Slave Multi-Module Battery System and Bypass Technology


A master-slave architecture is a common structure in battery management systems (BMS).


The master-slave architecture typically consists of a Battery Control Unit (BCU) as the master and multiple modules (slaves). The master unit oversees overall monitoring and management, while the slave units are responsible for monitoring voltage, temperature, and balancing control within individual battery modules. In a multi-module battery system, multiple battery cells form a module, and multiple modules are then integrated into a battery pack. This design facilitates expansion and maintenance.


Since modules support independent replacement, it is inevitable that modules with different State of Charge (SOC) may be mixed. Over time, consistency issues may also arise during use. Because modules are connected in series, SOC imbalances can significantly reduce the available capacity of the entire BMS. Many current market solutions use passive balancing methods, but these often have low efficiency and fail to meet customer requirements in many scenarios.


To address this issue, Bypass technology was developed. It enables intelligent module string switching, allowing for rapid module capacity balancing.


What is Bypass Technology and Why Does It Matter?


As home energy storage systems grow more complex with multiple battery modules working together, ensuring that all modules are in sync is a challenge. Bypass Technology is the solution to this problem.


Bypass Technology helps manage State of Charge (SOC) imbalances between modules by automatically switching them in and out of the system, balancing the charging process across all modules. This helps prevent issues such as energy loss, performance degradation, and system inefficiency.

ACE Residential ESS with bypass technology

Bypass Function Implementation


The diagram below illustrates the battery circuit design for Bypass functionality. Compared to traditional multi-module battery systems, a Bypass-enabled system includes two additional contactors within each module:


  • One contactor is connected in series with the battery cell stack.
  • The other contactor is connected in parallel with the battery cell stack.


Bypass Function Operating Principle


  • The BMS collects battery data from each module and determines whether Bypass activation is needed.
  • The BMS interacts with the inverter to control charge/discharge initiation and voltage regulation, ensuring a stable and safe Bypass process.
  • The BMS evaluates Bypass logic and sends Bypass switching commands to modules that meet the conditions.
  • Upon receiving the Bypass command, the module controls the contactors to either enter or exit Bypass mode.


ACE Residential ESS with bypass technology

Example of Bypass Logic in Operation


A test setup includes four battery modules connected to an inverter, with initial SOC values of 91%, 71%, 28%, and 3% respectively. The Bypass process operates as follows:


1. Charging begins.


  • Module 1 reaches 100% SOC first.
  • The BMS detects that the remaining modules need balancing and instructs Module 1 to enter Bypass mode.
  • The remaining three modules continue charging, while Module 1 stops charging.


four battery modules connected to an inverter, with initial SOC values of 91%, 71%, 28%, and 3% respectivelyModule 1 reaches 100% SOC


2. Module 2 reaches 100% SOC.


  • The BMS determines that the remaining two modules require further balancing.
  • Module 2 enters Bypass mode, allowing Modules 3 and 4 to continue charging.


Module 2 reaches 100% SOC

3. Module 3 reaches 100% SOC.


  • The BMS detects that Module 4 still requires balancing.
  • Module 4 enters Bypass mode, while previously charged modules exit Bypass mode and switch to discharge mode.


Module 3 reaches 100% SOC

4. Balancing is completed.


  • The three fully charged modules discharge until their SOC matches Module 4's SOC.
  • Module 1 exits Bypass mode, and all four modules resume normal operation together.


four modules resume normal operation together

The BMS balancing curve for the entire process is shown below:

BMS balancing curve

With the Bypass function, the BMS achieves rapid balancing, solving issues caused by:


  • Mixing modules of different capacities.
  • SOC inconsistencies during usage.


This prevents a reduction in usable energy and avoids performance degradation. Additionally, Bypass significantly improves battery deployment, installation, and maintenance efficiency, making it an essential feature in modern energy storage systems.



Click to Learn More about ACE Battery's Residential Energy Storage Systems with Bypass Technology:


Residential Energy Storage Systems

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