BESS Capex Calculation

This document describes how the total upfront investment cost (CAPEX) of a Battery Energy Storage System (BESS) is calculated for financial modeling.

The calculation produces a single Year-0 CAPEX value used across financial analysis.

Cost Structure

All cost inputs are defined on a per-kWh basis and assumed to scale linearly with installed energy capacity.

Core System Costs

Core system costs represent the technical building blocks of the BESS that enable energy storage and grid interaction. These include the battery pack, power conversion system (PCS), energy management and control systems (EMS), HVAC and safety systems, and overall system integration.

They are aggregated into a single base cost per kWh:

Cbase=Cbattery+CPCS+CEMS+CHVAC+CintegrationC_{base}=C_{battery}+ C_{PCS}+ C_{EMS}+ C_{HVAC}+ C_{integration}

Additional Project Costs

In addition to core system components, the model accounts for costs required to deploy the system as an operational, grid-connected project. These cover installation works, grid connection infrastructure, project development activities, and soft costs including contingency allowances.

Cother=Cinstallation+Cgrid+Cdevelopment+CcontingencyC_{other}=C_{installation}+ C_{grid}+ C_{development}+ C_{contingency}

Capex Calculation

The base investment cost is calculated by combining core system costs and additional project costs, then scaling by the total installed energy capacity:

CAPEXbase=(Cbase+Cother)⋅EkWhCAPEX_{base}=\left( C_{base} + C_{other} \right)\cdot E_{kWh}

Escalation

To account for expected cost uplift between the reference cost year and project execution, a linear escalation factor is applied:

CAPEXesc=CAPEXbase⋅rescCAPEX_{esc}=CAPEX_{base} \cdot r_{esc}

where rescr_{esc} is cost escalation rate

Total Capex

CAPEXtotal=CAPEXbase+CAPEXescCAPEX_{total}=CAPEX_{base}+ CAPEX_{esc}

The final CAPEX value is rounded to whole currency units for reporting.

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