Energy Arbitrage
Commercial Solution
Maximise Energy Savings with Battery Energy Storage Systems (BESS) designed for Time-of-Use (TOU) tariff optimisation.
At One Energy, we empower South African businesses to take control of their electricity costs with Battery Energy Storage Systems (BESS) designed for time-of-use (TOU) tariff optimisation.
With electricity tariffs rising rapidly – Eskom’s 2025/26 tariffs are up by 12.74% and municipal tariffs by 12.72% – and significant price gaps between peak and off-peak periods, BESS offers a proven solution to reduce energy expenses for commercial clients across major metro municipalities, and direct Eskom customers.
Why BESS for Commercial Energy Savings?
South Africa’s TOU tariffs, such as Ekurhuleni’s E-tariff and Eskom’s commercial tariffs (eg Miniflex, Megaflex), charge significantly higher rates during peak hours (early morning and late afternoon) compared to off-peak periods.
Peak tariffs can be 3-4 times higher than off-peak rates, which means that when production schedules cannot be shifted to off-peak times, businesses are locked into paying a very heavy premium for power – and diminished profitability.
For example, in Ekurhuleni under the E-tariff, peak rates can reach R10.18/kWh during high-demand seasons, while off-peak rates drop to R1.52–R1.71/kWh. By charging a BESS during off-peak hours and discharging during peak periods, businesses could save R3.01 per kWh, directly boosting their bottom line, often reducing energy costs by 20–40% depending on usage patterns.
Our BESS solutions are tailored for businesses with power needs from 50 kVA and more, offering flexibility, scalability, and seamless integration. Whether you’re a factory, warehouse, retail complex, hospitality venue, or commercial office park, our systems help you:
- Slash Electricity Costs: Shift consumption from peak to off-peak tariffs, leveraging the price differential for maximum savings.
- Operate Off-Grid: Our BESS solutions are designed to function independently of solar panels, eliminating the need for landlord approvals or complex grid-tied integrations.
- Enhance Existing Systems: For businesses with grid-tied solar, we offer AC-coupled upgrades to integrate BESS, optimising both solar and grid power usage.
- Boost Reliability: Mitigate the impact of power outages and grid instability with reliable backup power.
Key Benefits of One Energy’s BESS Solutions
No Solar or Landlord Approval Required
Our off-grid BESS systems charge exclusively from low-cost grid power during off-peak hours, bypassing the need for solar panels or landlord permissions. This simplifies deployment and reduces regulatory hurdles.
No Inverter Size Restrictions
Unlike grid-tied systems, where inverter capacity is limited to 75% of installed capacity, our off-grid BESS solutions face no such constraints, allowing maximum flexibility in system design.
AC-Coupled Upgrades for Existing Systems
If you already have a grid-tied solar system, our team can assess your setup and propose AC-coupled BESS upgrades to enhance savings without replacing existing infrastructure.
Tailored for Your Needs
We design systems from 50 kVA to 500 kVA, ensuring the perfect fit for your facility’s energy profile and TOU tariff structure.
In-depth Analyses
Our team will undertake an analyses of your tariff structure and consumption patterns, to forecast savings based on optimised battery discharge. These analyses show that the cost reduction can bring the BESS solution into positive cash flow within 4-7 years. We take into account the impact of tariff structures, potential tariff escalation over time, and battery degradation with use.
Who Can Benefit?
Our solutions are ideal for:
- Ekurhuleni E-Tariff Customers: Industrial and commercial facilities in Ekurhuleni facing high peak rates.
- Major Metro Municipalities: Businesses in Johannesburg, Cape Town, Durban, and other metros with TOU tariffs.
- Direct Eskom Customers: Commercial clients on tariffs like Miniflex or Megaflex, seeking to optimise energy costs.
How Much Can You Save?
By charging BESS during off-peak hours and discharging 80% of capacity during peak periods, businesses can significantly reduce electricity costs. Below are example savings for systems sized at 50 kVA, 100 kVA, and 250 kVA, based on Ekurhuleni’s E-tariff rates for High Season (R10.18/kWh peak / R1.71/kWh off-peak) and Low Season (R3.09/kWh peak / R1.52/kWh off-peak), with 85% round-trip efficiency and two daily cycles (morning and evening peaks).
Calculations assume a 3-month high-demand season (June–August) and a 9-month low-demand season, with an 8% annual tariff escalation.
Case study 1: 50 kVA BESS (80 kWh Capacity)
| 50kVa BESS | High season | Low Season |
|---|---|---|
| Daily Savings |
80 kWh x 80% x (R10.18 - R1.71) x 85%
R431.46 / day |
80 kWh x 80% x (R3.09 - R1.52) x 85%
R85.14 / day |
| Annual Savings | (R431.46 x 90 days) + (R85.14 x 275 days) | R62,218 / year |
Case study 2: 100 kVA BESS (160 kWh Capacity)
| 100kVa BESS | High season | Low Season |
|---|---|---|
| Daily Savings |
160 kWh x 80% x (R10.18 - R1.71) x 85%
R862.92 / day |
160 kWh x 80% x (R3.09 - R1.52) x 85%
R170.27 / day |
| Annual Savings | (R862.92 x 90 days) + (R170.27 x 275 days) | R124,436 / year |
Case Study 3: 250 kVA BESS (400 kWh Capacity)
| 250kVa BESS | High season | Low Season |
|---|---|---|
| Daily Savings |
400 kWh x 80% x (R10.18 - R1.71) x 85%
R2,157.31 / day |
400 kWh x 80% x (R3.09 - R1.52) x 85%
R425.68 / day |
| Annual Savings | (R2,157.31 x 90 days) + (R425.68 x 275 days) | R311,090 / year |
(Assumes average TOU spread of R6.00/kWh differential between low and peak tariff rates. Actual savings depend on tariff, consumption profile, and system configuration.)
Savings vary based on specific tariff structures, usage patterns, and system sizing. Our team conducts detailed assessments to maximize your ROI.
Metro Comparison - Electricity Arbitrage Options
| Metro Municipality | Season | Illustrative Peak Energy Charge (c/kWh) | Illustrative Off-Peak Energy Charge (c/kWh) | Typical Savings Ratio (Peak to Off-Peak) |
|---|---|---|---|---|
| Ekurhuleni | Winter | High (e.g., > 400) | Low (e.g., < 150) | 3:1 or more |
| Summer | Moderate (e.g., > 200) | Very Low (e.g., < 100) | 2:1 or more | |
| Johannesburg | Winter | Very High (e.g., > 600) | Low (e.g., < 200) | 3:1 or more |
| Summer | Moderate (e.g., > 250) | Very Low (e.g., < 150) | 2:1 or more | |
| Tshwane | Winter | Very High (e.g., > 470) | Low (e.g., < 110) | 4:1 or more |
| Summer | Moderate (e.g., > 190) | Very Low (e.g., < 90) | 2:1 or more | |
| Durban | Winter | High (e.g., > 430 | Low (e.g., < 90) | 4:1 or more |
| Summer | Moderate (e.g., > 150) | Very Low (e.g., < 80) | 2:1 or more | |
| Cape Town | Winter | Very High (e.g., > 600) | Low (e.g., < 150) | 4:1 or more |
| Summer | Moderate (e.g., > 200) | Very Low (e.g., < 100) | 2:1 or more |
Why Choose OneEnergy?
Expertise
With years of experience in South Africa’s energy sector, we design BESS solutions tailored to local tariffs and grid conditions.
End-to-End Service
From system design and installation to maintenance and performance monitoring, we ensure seamless implementation.
Proven ROI
Our systems are engineered to deliver rapid payback periods, often within 4–7 years, depending on tariff escalation and usage.
Local Support
As a proudly South African business, we understand the unique challenges of Ekurhuleni, major metros, and Eskom customers.
Take Control of Your Energy Costs Today
Rising electricity costs and grid unreliability don’t have to hurt your bottom line. One Energy’s BESS solutions offer a smart, scalable way to leverage TOU tariffs for significant savings.
Whether you’re starting fresh or upgrading an existing solar system, we’ll tailor a solution to fit your needs. BESS for energy arbitrage is a powerful antidote for TOU tariffs, dramatically reducing energy costs and securing energy supply.