The Colorado Office of the Utility Consumer Advocate is urging residential customers to shift heavy electricity use away from evening hours as Xcel Energy’s summer time-of-use rates took effect Monday.

The two-tier summer schedule approved by the Public Utilities Commission charges significantly more during peak weekday evenings. For many households, the flat-rate alternative sits at about 10.4 cents per kilowatt-hour around the clock, while time-of-use pricing swings from roughly 7.9 cents off-peak to 21.3 cents during the expensive 5 p.m. to 9 p.m. weekday window.

The office said paying attention to those usage windows can reduce summer energy costs.

As the utility adds more renewable energy to the grid, intermittent sources such as wind and solar require dispatchable sources like gas peaker plants or batteries to meet grid demand during high-demand evening hours when renewable output drops. Time-of-use pricing encourages customers to shift usage to reduce reliance on those more expensive peaking resources, said Excel Energy.

Under the structure approved by the Colorado Public Utilities Commission, on-peak rates apply from 5 p.m. to 9 p.m. Monday through Friday. Off-peak rates cover all other hours, including full weekends and federal holidays. The previous mid-peak tier has been eliminated.

The Office of the Utility Consumer Advocate recommended load shifting as the key to savings under time-of-use pricing. That means moving the operation of energy-intensive appliances such as central air conditioning, clothes washers and dryers, dishwashers, electric ovens and EV chargers out of the peak evening period. Recommended strategies include pre-cooling homes earlier in the day, running laundry at night or on weekends, and setting programmable thermostats or charging timers.

Customers with inflexible schedules, such as those with medical needs or evening work shifts, can opt out of time-of-use rates at any time and switch to the seasonal flat-rate plan. However, according to Xcel, a switch to flat-rate billing means not being able to change back to TOU billing for one year.

The change can be requested through the Xcel Energy My Account portal or by calling customer service at 1-800-895-4999.

The Office of the Utility Consumer Advocate represents residential, small business and agricultural utility customers in proceedings before the Colorado Public Utilities Commission. It does not regulate utilities but advocates for equitable rates and policies.