DC Coupling for Commercial Battery Storage |Alternergy

DC Coupling for Commercial Battery Energy Storage Systems


Few choices in commercial solar battery storage impact performance, cost and simplicity more than AC vs DC coupling. DC-coupled battery storage has emerged as a game-changing solution for optimising new solar PV systems.

With fewer conversion losses, lower hardware requirements, and faster commissioning, battery storage DC coupling offers compelling advantages for installers and end users alike.

Let’s get into the key differences between an AC and DC-coupled storage system, and see how integrated solutions like Dunext’s PowerHill commercial battery storage help forward-thinking installers stay ahead.


AC-Coupled vs DC-Coupled Battery Energy Storage

AC-Coupled vs DC-Coupled Battery Energy Storage | AlternergyAC-Coupled vs DC-Coupled Battery Energy Storage | Alternergy

What is AC Coupling in Solar Battery Storage Systems?


In an AC-coupled storage system, the DC electricity generated by solar panels is first converted to AC by a grid-tied inverter. This AC power can then be used on-site, exported to the grid, or reconverted to DC by a second inverter to charge a battery.


Advantages:

  • Ideal for retrofitting existing PV systems with battery storage
  • PV and battery systems operate independently, offering flexibility
  • Familiar architecture for larger or off-grid systems


Disadvantages:

  • Multiple conversions reduce overall efficiency
  • Requires two inverters, increasing cost
  • Installation and commissioning can be more complex


While AC coupling remains useful for specific scenarios, its lower efficiency and higher hardware needs can limit its appeal in new commercial setups.

What is DC-Coupled Storage in Commercial Solar PV Systems?

 

In a DC-coupled C&I battery storage system, power from the solar panels flows straight to the battery via the DC bus without any AC/DC conversion. Maximum Power Point Tracking (MPPT) modules optimise energy harvest, and a Power Conversion System (PCS) converts stored energy to AC as needed.

 

Why Installers Are Shifting to DC Coupling Battery Storage

 

  • Higher efficiency: Avoids DC-AC-DC losses, preserving more of the energy generated
  • Lower hardware costs: Fewer inverters, cables, and components
  • Faster installation: Reduced setup time and simpler commissioning
  • Easier grid integration: Less coordination and fewer permissions required
  • Smaller footprint: Easier to deploy in constrained commercial spaces


DC coupling allows installers to design commercial battery energy storage systems from the ground up with performance, simplicity, and ROI in mind—rather than adapting to legacy setups.

Ideal applications include:

  • Price arbitrage and demand-side response
  • Peak shaving and load shifting
  • Emergency backup or off-grid capabilities
  • EV charging integration and virtual power plant (VPP) participation

 

Key Differences Between DC and AC-Coupled Storage System 

Key Differences Between a DC and AC-Coupled Storage System? | AlternergyKey Differences Between a DC and AC-Coupled Storage System? | Alternergy

Dunext PowerHill Commercial ESS: Leading the DC Coupling Charge


This innovative all-in-one energy storage system by Dunext is one of the first in the UK to fully embrace DC Coupling. While supporting both coupling options, Dunext PowerHill is optimised for DC-connected performance in commercial PV installations.


Key highlights:

  • Integrated solution: Includes PCS, MPPT, battery modules, HVAC, and fire suppression
  • 2-hour install: Pre-assembled design only needs external wiring
  • 5%+ efficiency gain: No need for separate PV inverters
  • Modular and scalable: Add up to six units, adapt as you grow
  • Versatile application: Price arbitrage, backup power, peak shaving and more


It also features advanced safety technologies, including real-time thermal monitoring and a gas-based suppression system that activates within six seconds—providing peace of mind alongside performance.

 

DC Coupling: A Smarter Fit for Commercial Installers


For new commercial PV and storage systems, DC coupling is the more efficient and cost-effective option. Solutions like Dunext’s PowerHill demonstrate how DC coupling can streamline installation, lower costs, and boost long-term performance - making it the smart choice for UK solar professionals looking to stay ahead in a rapidly evolving energy sector.

 

Alternergy offer a variety of commercial energy storage systems


We are approved solar PV and battery storage distributors of leading manufacturers such as Dunext, Huawei FusionSolar, and Sungrow in the UK.

Browse our range of residential, and C&I BESS products, each with modular battery options to tailor a system to specific PV Installations.

 

Call us to learn more about battery storage benefits and to discuss your energy storage requirements. Or alternatively get a free, no obligation quote by simply filling out an enquiry form and our team will get in touch.

 


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