How Batteries Combat Time of Use Rates

Time of use rate plans are designed for utilities like PG&E and SMUD, to reflect demand on their grids. In the early evenings when the sun goes down, renewable energy from solar goes away and homeowners use more power coming home from work and school.

Using HVAC systems (air conditioning), ovens, washers, dryers, etc increase the demand on the grid. The utilities increase their rates during these increased demand times. Battery storage can help offset this cost by charging batteries during the day with less expensive electricity, whether through an attached solar system or from the grid, and then switch to a “self-consumption” mode when the rates increase.

The batteries systems include monitoring a home or businesses consumption. They are programmed to match the rate tariff schedule of the utility. For example, PG&E’s rate tariff, E-TOU option D, increases the rates for residential customers from the hours of 5-8pm (this is a common rate that new solar customers are forced to use). The battery is programmed in “self-consumption” mode during these hours.

During the day, the battery is charged (from existing solar on site or from the grid). When the rates increase the battery will supply the loads instead of the utility. One specific thing to note, most utilities including PG&E, do not allow exporting electricity from the battery to the grid. Customers are not allowed to charge at the low cost and then sell back to the utility at the high cost.

Chat with one of our solar and battery system experts to explore options for your home.