Retail Energy Time-Shift

Retail electric energy time-shift involves storage used by energy end users (utility customers) to reduce their overall costs for electricity. Customers charge the storage during off-peak time periods when the retail electric energy price is low, then discharge the energy during times when on-peak time of use (TOU) energy prices apply. This application is similar to electric energy time-shift, although electric energy prices are based on the customer’s retail tariff, whereas at any given time the price for electric energy time-shift is the prevailing wholesale price.

For example, a hypothetical TOU tariff is shown in Figure 16. It applies to Commercial and Industrial electricity end users from May to October, Monday through Friday, whose peak power requirements are less than or equal to 500 kW.

As shown in Figure 16, energy prices are about 32¢/kilowatt hour (kWh) on-peak (12:00 p.m. to 6:00 p.m.). Prices during partial-peak (8:30 a.m. to 12:00 p.m. and 6:00 p.m. to 9:30 p.m.) are about 15¢/kWh, and during off-peak (9:30 p.m. to 8:30 a.m.), prices are about 10¢/kWh.

Technical Considerations

Storage System Size Range: 1 kW – 1 MW
Target Discharge Duration Range: 1 – 6 hours
Minimum Cycles/Year: 50 – 250

The maximum discharge duration in this case is determined based on the relevant tariff. For example, for the assumed hypothetical tariff, there are six on-peak hours (12:00 p.m. to 6:00 p.m.). The standard value assumed for this case is five hours of discharge duration.