• Dagong ESS

How to Size a Battery Energy Storage System for Your Project

What is Battery Energy Storage System (BESS) Sizing?

BESS sizing is the process of determining how much energy storage (measured in kilowatt-hours or megawatt-hours) and power output (measured in kilowatts or megawatts) your project needs. Whether for residential solar, commercial peak shaving, or utility-scale backup, correct sizing ensures optimal performance, cost efficiency, and long-term reliability.

Types of Battery ESS Projects and Their Sizing Needs

• Residential ESS

Common size: 5kWh to 30kWh

Use case: Backup power, solar self-consumption

• Commercial & Industrial ESS (C&I)

Common size: 100kWh to 500kWh

Use case: Peak shaving, time-of-use optimization, backup power

• Utility-Scale or Containerized ESS

Common size: 1MWh to 5MWh+

Use case: Grid support, renewable smoothing, VPP integration

Dagong ESS provides modular and scalable battery solutions to suit all scenarios.

Key Factors for Sizing a Battery ESS

1. Daily Load Demand (kWh)

Measure the total energy consumption per day. This defines the base energy your ESS needs to store.

Example:
If your facility uses 1,500 kWh/day and you want 50% backup:
ESS Capacity = 1,500 kWh × 50% = 750 kWh

2. Peak Load (kW or MW)

Identify the maximum power your system needs to deliver during demand surges or outages.
This defines the output power rating of the inverter and battery system.

3. Depth of Discharge (DoD)

Most LFP batteries allow 90–95% DoD.
To ensure long life, multiply your needed capacity by a safety factor:

Usable capacity = Total capacity × DoD
If you need 500 kWh usable:
Total capacity = 500 / 0.9 = ~556 kWh

4. Autonomy Time (Backup Duration)

How many hours or days do you want backup for?

Formula:
ESS Capacity = Load Power (kW) × Backup Hours / DoD

5. Charging Source & Speed

From PV: size according to expected solar generation

From grid: match charging time with utility rate schedule

6. System Expansion Needs

Plan future energy growth

Choose modular ESS that supports parallel expansion

Applications That Require Accurate ESS Sizing

Factories with peak demand charges

Commercial buildings on time-of-use tariffs

EV charging stations with high power fluctuation

Off-grid homes with solar PV

Microgrids with mixed generation sources

Price of a Properly Sized ESS

The cost of an ESS is closely related to its size:

System Size	Typical Use Case	Estimated Cost (EXW)
10kWh	Residential solar + backup	$2,000–$4,000
144kWh Air-Cooled	Commercial peak shaving	$28,000–$50,000
372kWh Liquid-Cooled	Industrial/factory use	$70,000–$110,000
3.35MWh Container	Utility/EV infrastructure	$500,000–$800,000

How to Select the Right ESS Size for Your Project

• Analyze Energy Usage Data

Use 12 months of utility bills or a smart meter

• Define Project Goals

Cost savings? Backup? Renewable optimization?

• Work With a Professional

Suppliers like Dagong ESS offer expert sizing based on your region, application, and budget

• Plan for the Future

Choose modular, expandable systems to scale with load growth

• Ensure Safety & Compliance

All systems should be CE, UN38.3, MSDS, IEC, and 3C certified

How Long Does a Properly Sized ESS Last?

With high-quality LFP batteries and optimal sizing:

• Cycle Life: 8,000+ full cycles

• Lifespan: 15+ years

• Over/undersizing can reduce efficiency or lifespan—accuracy matters.

The Supplier of Scalable ESS Solutions: Dagong ESS

Dagong ESS offers a full portfolio of customizable and scalable battery energy storage systems for every project size:

• Residential Systems

Stackable: 5kWh to 80kWh

Wall-mounted: 5kWh to 10kWh

Rack-based: 5kWh to 30kWh

• Commercial & Industrial Systems

Air-cooled: 100kWh–241kWh

Liquid-cooled: 215kWh–372kWh

• Containerized Utility Solutions

3.35MWh Liquid-Cooled ESS

5MWh Air-Cooled ESS

All systems are built with LFP cells, integrated EMS, and remote monitoring, and come with global certifications.

Need help sizing your battery storage system? Contact Dagong ESS for a free consultation:
Email: sales@dagongess.com
Website: 🌐 www.dagongess.com