Electricity tariff comparison: practical guide

What 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

Period cost = energy × unit rate + days × standing charge − credit. Crossover solves the two cost equations.

Worked example

Illustrative inputs and their result.

Example inputs

Energy over comparison period (kWh)

4200

Days in comparison period

365

First unit price (€/kWh)

0.3

First standing charge (€/day)

0.6

First period credit (€)

100

Second unit price (€/kWh)

0.27

Second standing charge (€/day)

0.8

Second period credit (€)

0

Calculated example result

Second Tariff Saving

-€47.00

Crossover KWh

5,766.67 kWh

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

Use prices on the same tax basis and include all recurring charges in standing costs. Credits may have eligibility conditions; time-of-use tariffs need weighted unit rates.

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