BESS Sizing Guide

How to Size BESS for a Diesel Generator Hybrid System

Quick answer: Do not size a BESS from diesel-generator nameplate alone. A 500kW generator does not automatically require a 500kW or 500kWh battery. Start with the load profile and define the battery’s job: peak support, generator-off operation, solar shifting, reserve, backup or multiple functions.

What determines BESS power in a diesel hybrid?

Battery power is driven by the load the PCS must carry, rapid load changes, motor-start requirements, generator operating limits and the intended control strategy. Short peaks and continuous power should be identified separately.

What determines BESS energy?

Energy capacity depends on how much load the battery must support and for how long, plus the usable SOC window, losses, auxiliaries and lifecycle design margin. The simple starting point is load kW × required hours, followed by engineering adjustments.

What information should be provided?

Send load profile, generator kW/kVA, number of generators, minimum loading constraints if applicable, fuel-reduction objective, PV capacity, critical loads, outage pattern, voltage and operating schedule.

Which pages should I use next?

Review Diesel + BESS, Microgrid & Backup Power, the Mining solution and our BESS Sizing Calculator.

Get a preliminary project estimate

Use Zevonexa’s free calculator, then send your actual project inputs for engineering review.

Open BESS Sizing Calculator → Request a BESS Solution →

Important sizing limitation

These examples are screening guidance, not a final electrical design or performance guarantee. Final equipment selection requires project-specific engineering, applicable standards, equipment ratings and verified site data.