BESS Peak Tariff Mitigation
Battery Energy Storage System countering Eskom's 6x peak tariff differential
Key Metrics
Target Capacity
121.94 MWh
Current: 4 MWh (3.28%)
Annual Arbitrage
R 64.13M
Pure profit (6x price diff)
Demand Reduction
R 12.97M/yr
24,388 kVA reduction
Total BESS Value
R 77.10M/yr
Arbitrage + Demand
Monthly BESS Arbitrage & Demand Savings
Breakdown of BESS revenue streams (R thousands)
Arbitrage Mechanics
Monthly arbitrage calculation breakdown (R thousands)
Daily Charge/Discharge Cycle
BESS State of Charge throughout the day (%)
BESS Savings Composition
Monthly gross savings breakdown
Arbitrage Savings
Demand Reduction
Net BESS Performance
Revenue streams vs operational costs (R thousands)
Arbitrage Formula
SBESS,arb = Edischarge × τPeak − Echarge × τOff-Peak
Edischarge: 97.40 MWh/month (3.2 MWh × 30.44 days)
Echarge: 108.22 MWh/month (accounting for 90% efficiency)
τPeak: R 6.47/kWh | τOff-Peak: R 1.08/kWh
Demand Reduction Formula
SBESS,dem = ΔD × τdemand
ΔD: Peak demand reduction = 600 kVA
kreduction: 150 kVA/MWh (empirical coefficient)
τdemand: R 44.32/kVA/month
Monthly BESS Financial Summary
| Component | Monthly | Annual |
|---|---|---|
| Peak Avoided Cost (97.4 MWh × R6.47) | R 630,597 | R 7,567,164 |
| Charging Cost (108.2 MWh × R1.08) | −R 116,772 | −R 1,401,264 |
| Net Arbitrage Savings | R 513,825 | R 6,161,680 |
| Demand Reduction (600 kVA × R44.32) | R 26,592 | R 319,104 |
| BESS Operational Cost (4 MWh × R165K) | −R 660,000 | −R 7,920,000 |
| Net BESS Position | −R 119,583 | −R 1,439,216 |
Key Insight: At full deployment, PV profit (R132.65M) fully covers BESS operational cost (R45.73M), making BESS operate as a "free" asset. All BESS arbitrage (R64.13M) and demand reduction (R12.97M) become pure profit totaling R77.10M/year. This is why BESS is the cornerstone of financial transformation.