As more businesses and facilities adopt renewable energy, Battery Energy Storage Systems (BESS) have become essential for ensuring stable, efficient, and cost-effective power management. However, the benefits of a BESS can only be fully realised when it is properly sized to suit the application.
Whether you’re powering a remote site, providing backup for critical infrastructure, or supporting grid-connected operations, this step-by-step guide will help you size a BESS system that meets your unique energy needs.
1. Define the Objective of the BESS
The first step in sizing a BESS system is to clearly define its intended purpose. Ask yourself:
- Will the BESS be off-grid or grid-connected?
- Will it be used for peak shaving, backup power, or continuous operation?
- What kind of equipment or infrastructure will the system support?
Clearly defining your application will determine everything else—from battery capacity and voltage to system architecture and control strategy.
2. Understand Your Load Requirements
Next, assess the amount of energy you need to store and supply.
- Analyse your historical energy usage if available.
- Estimate future demand based on expansion plans or new equipment.
- Identify your peak loads and average daily loads.
These figures are critical for calculating battery size, inverter capacity, and the overall system performance.
3. Evaluate Your Renewable Energy Sources
If your BESS will be paired with renewables like solar or wind, you’ll need to:
- Evaluate availability and consistency of the energy source
- Understand the generation profile (e.g., solar peaks mid-day)
- Consider the size and type of panels or turbines to be used
This will influence how frequently and how fully your batteries can be charged.
4. Determine Storage Duration, Battery Type and Plan for Scalability
Not all BESS systems are created equal. The required storage duration depends on your use case:
- Short duration (1–2 hours): peak shaving or fast response
- Long duration (4–8+ hours): off-grid supply or load shifting
- Multi-day support: remote infrastructure and critical backup
When selecting a battery, evaluate:
- Cycle life and longevity
- Round-trip efficiency
- Maintenance costs
- Power and energy density
At DEUTZ, our modular battery systems are available in low voltage (9 kVA to 36 kVA) and high voltage (45 kVA to 90 kVA). Both options are designed to be scalable and adaptable.
5. Consider System Efficiency
Batteries are not 100% efficient. When sizing your BESS, account for:
- Round-trip efficiency, typically between 85–95%
- Environmental losses, such as heat and inverter inefficiencies
A system sized only for theoretical performance might fall short in real-world conditions.
6. Plan for Future Scalability
Your energy needs will likely change. A BESS that’s too small may quickly become insufficient.
That’s why DEUTZ systems are built with modular expandability—allowing you to increase capacity and power output without replacing the entire system. This approach future-proofs your investment and supports long-term energy resilience.
7. Evaluate the Cost-Effectiveness
Before finalising your system size, consider both the technical and financial aspects:
- Initial setup cost (CAPEX)
- Operating and maintenance costs (OPEX)
- Battery lifespan and return on investment (ROI)
- Potential savings from fuel offset, load shifting, or tariff arbitrage
- Government incentives or rebates
Simulation tools and our Power Solutions team can assist you with designing and estimating system performance, helping you make informed decisions with confidence.
Ready to Get Started?
Designing the right battery storage system isn’t a one-size-fits-all process. At DEUTZ Australia, we work with you to customise a solution that meets your site requirements, energy load, and future growth plans.
Let us help you take the guesswork out of BESS sizing—and build a smarter, scalable energy future.
Explore more at: https://www.deutz.com.au/bess