Beginning this month, Southern California Edison will begin transitioning residential customers to new “time-of-use” rate plans that would will charge more for electricity during peak hours, from 4 p.m. to 9 p.m.

SoCal Edison provides electricity to millions, including in Los Angeles, Orange, San Bernardino, Ventura and Riverside counties, and plans to move 2.3 million residential customers to the new plans in six monthly waves through April.

Unlike tiered rates based solely on how much energy each customer uses, the plans will offer pricing based on when and how much energy they use.

The utility said the new “time-of-use” rate plans are meant to benefit customers who can shift their electricity usage away from times of day when electricity costs more to deliver. 

That means using appliances, charging electric vehicles or using thermostats before or after the 4 to 9 p.m. “On-Peak” period, when the electrical grid isn’t as stressed.

How much customers pay will also depend on the time of year.

“It is likely that on a TOU rate plan, your winter bills will be lower than you are used to, while your summer bills will be higher,” Edison says on its website.

Edison will offer three different “time-of-use” rate plans, and customers will be automatically switched to the lowest cost plan based on their historical usage, according to the utility.

• TOU 4-9 p.m.: For households who can reduce their energy usage between 4 p.m. to 9 p.m.
• TOU 5-8 p.m.: Benefits households who can lower their energy usage between 5 p.m. and 8 p.m.
• TOU PRIME: This plan is for households with electric or plug-in hybrid vehicles, a residential battery, or an electric heat pump system for water or space heating.

Edison has an online calculator  that is designed to help customers identify the least expensive plan based on their past usage data.

Another energy use calculator can help customers estimate savings from shifting appliance use to off-peak hours.

Edison says shifting energy use to morning and midday hours taps into cleaner, renewable resources.

Customers will be notified by mail a couple months before their plans are switched, and letters will include a comparison of what customers’ pay each year currently and what they would pay under new plans, Edison said.

Customers can then choose if they want to opt out before their scheduled transition date, using the reply card included with the notification letter, by completing the online form or calling 877-287-2140.

Those who take no action will be automatically moved to a “time-of-use” plan, and will see it reflected on an upcoming bill.

Customers switched to a “time-of-use” plan through April will get 12 months of bill protection, according to Edison.

“If you pay more on a TOU rate plan for the first 12 months than you would have paid on your previous tiered rate plan, SCE will provide you a one-time bill credit for the difference,” Edison says on its website.

Here are the rates during the summer. Winter rates can also be found online.

TOU 4-9 p.m. plan:

TOU 5-8 p.m. plan:

TOU PRIME plan: