Time Of Use Savings Calculator

Background.

A reader arrives at Time Of Use Savings Calculator to compare avoided peak purchase with extra off-peak energy required after storage or shifting loss. Time-of-use arbitrage is valuable only when the peak-off-peak spread exceeds efficiency losses and applicable charges. For that reason, this page names its convention as “savings = shifted kWh × peak rate − shifted kWh ÷ efficiency × off-peak rate.”

The editable entries are energy shifted from peak to off-peak, peak energy rate, off-peak energy rate, storage or shifting efficiency. Use values from the document or measurement that governs this time of use savings question; the defaults are only the worked fixture below. Before relying on the number, check this time of use savings boundary: demand charges, export credits, battery degradation, interval windows and tariff eligibility can reverse the result.

U.S. Energy Information Administration, Electricity explained—prices and tariffs documents the convention or governing rule used here. The time of use savings output is a transparent scenario under those facts: it does not manufacture an unentered market price, professional determination, carrier quote, legal eligibility finding or locally adopted code value.

What is time of use savings calculator?

Time Of Use Savings is the relationship behind this decision: time-of-use arbitrage is valuable only when the peak-off-peak spread exceeds efficiency losses and applicable charges. On this page it means savings = shifted kWh × peak rate − shifted kWh ÷ efficiency × off-peak rate. Demand charges, export credits, battery degradation, interval windows and tariff eligibility can reverse the result; that is the line between the reported quantity and a broader building systems analysis.

How to use this calculator.

1. 01Confirm that “savings = shifted kWh × peak rate − shifted kWh ÷ efficiency × off-peak rate” matches the time of use savings convention you need.
2. 02Replace the fixture values for energy shifted from peak to off-peak, peak energy rate, off-peak energy rate, storage or shifting efficiency with dated values from the governing record.
3. 03Keep all currencies, measurement units and time periods on the same basis before calculating.
4. 04Read estimated monthly time-of-use savings together with this boundary: Demand charges, export credits, battery degradation, interval windows and tariff eligibility can reverse the result.

The formula.

The calculation uses savings = shifted kWh × peak rate − shifted kWh ÷ efficiency × off-peak rate. In this time of use savings model, the entered terms are energy shifted from peak to off-peak, peak energy rate, off-peak energy rate, storage or shifting efficiency. Time-of-use arbitrage is valuable only when the peak-off-peak spread exceeds efficiency losses and applicable charges, which is why the relationship is presented under this name rather than as a universal alternative. Demand charges, export credits, battery degradation, interval windows and tariff eligibility can reverse the result. Calculations keep full decimal precision through the relationship and round only the returned display values.

A worked example.

Frequently asked questions.

References& sources.

1. [1]U.S. Energy Information Administration, Electricity explained—prices and tariffs. Retrieved 2026-08-07. access: open unless marked otherwise.
2. [2]U.S. Energy Information Administration. Electric power monthly — average retail price of electricity. Retrieved 2026-08-07. independence: secondary-check; access: open.
3. [3]U.S. Department of Energy. Energy Saver. Retrieved 2026-08-07. independence: primary; access: open.