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Battery tariff arbitrage: practical guide
This guide explains how to use the Count.ie battery tariff arbitrage. Estimate savings from storing cheaper electricity for peak use. Follow the inputs, method and worked example below, then compare your own scenario.
Guide written .
Open the Battery tariff arbitrage calculatorWhat to prepare
- Use meter readings, bills, equipment specifications and actual tariff periods where possible.
- Separate power in kW from energy in kWh and daily use from annual use.
- Identify whether efficiency, standing charges and losses are included in the chosen model.
Understand the inputs
The calculation method
Delivered energy = capacity × usable fraction. Purchased energy = delivered ÷ round-trip efficiency. Saving deducts charging cost.
Worked example
Illustrative inputs and their result.
Example inputs
- Battery capacity (kWh)
- 10
- Usable depth of discharge (%)
- 90
- Round-trip efficiency (%)
- 90
- Full-equivalent cycles each year
- 300
- Charging tariff (€/kWh)
- 0.12
- Avoided peak tariff (€/kWh)
- 0.35
- Battery installed cost (€)
- 6000
Calculated example result
- Annual Saving
- €585.00
- Simple Payback Years
- 10.26 years
How to interpret the result
Energy consumption and money saved are different outputs. Results based on entered prices or efficiencies are scenarios, not a performance guarantee, installer quote or measured emissions assessment.
Use the same demand and time horizon for each option. Test a less favourable tariff, lower efficiency or lower use to see how sensitive the estimated saving is.
Common mistakes to avoid
- Do not count the same efficiency loss twice.
- Keep standing charges and unit charges separate when the model distinguishes them.
- Check seasonal demand, export restrictions and tariff assumptions before extrapolating.
Assumptions and sources
Assumes enough cheap-rate charging time and peak demand. Excludes degradation, standby power, financing and backup value; solar opportunity cost can be entered as the charging tariff.
If your case falls outside this scope, use a more suitable calculator or contact us about an unclear method.