The time-of-day electrical rates for Xcel Energy in Colorado changed fifteen days ago (on November 1, 2025). In this posting I offer a few thoughts about how this might affect a home owner who is a customer of Xcel Energy in Colorado.
What changed? The way it was sixteen days ago was like this:
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- On weekends the electricity was cheap all day.
- Monday through Friday, starting at 1PM, it was smart to avoid purchasing electricity from Xcel because the price would go up a bit. This situation worsened at 3PM each day as the electricity got even more expensive. Then at 7PM each day the electricity would get cheap again.
Starting fifteen days ago it changed:
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- On weekends the electricity is cheap all day (same as before).
- Monday through Friday, starting at 5PM, it is smart to avoid purchasing electricity from Xcel because the price goes way up. Then at 9PM each day the electricity gets cheap again.
Some home owners in Colorado who get their electricity from Xcel Energy have made the decision to pay extra for flat-rate billing. If so then none of this applies to them.
But anyway for those who are in Colorado and who get their electricity from Xcel Energy, the changes as of fifteen days ago are like this:
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- instead of avoiding purchasing electricity starting at 1PM or 3PM each day, you can wait until 5PM to avoid purchasing electricity.
- instead of waiting until 7PM to resume purchasing electricity, the smart thing to do is to wait until 9PM to resume purchasing electricity.
The situation on the weekends is the same as before. No need to pay attention to the time of day when making electricity purchasing decisions.
Here are a few general guidelines and suggestions. These are of course one person’s views on these things — you can make your own personal choices about these things.
First, assuming your house lighting is mostly LEDs, absolutely do not pay any attention to time of day for turning lights on and off. Do not for example sit in the dark from 5PM to 9PM thinking that this will meaningfully affect your electric bill or meaningfully benefit the environment. And in my view there is no need to obsessively turn off a light for a minute or two when one is momentarily out of the room. Accidentally leaving an LED light on for an unnecessary extra hour during peak pricing is going to add maybe two-tenths of a cent to the electric bill. Accidentally leaving an LED light on for an unnecessary extra hour during off-peak pricing is going to add less than one-tenth of a cent to the electric bill.
In most homes, the only meaningful big power loads are a very small number of appliances which I call “the big five”:
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- air conditioners
- electric ovens
- electric clothes dryers
- EV chargers
- electric cooktops
This means that in most homes, these are the only things for which you might want to wait until 9PM (Monday through Friday) to use them.
Note that I do not include the clothes washer or dishwasher or refrigerator on this list of “the big five”. Yes of course they do use some electricity, and they are physically large, and they make some sound, so we really do notice when they are running. But they do not use nearly as much electricity as one might think.
Air conditioners. Yes, if you have any air conditioners, on a weekday it is smart to avoid using them between 5PM and 9PM.
Gas oven. Your oven might be gas instead of electric. if so, then that does not require any waiting until 9PM.
Gas clothes dryer. Your clothes dryer might be gas instead of electric. if so, then that does not require any waiting until 9PM.
Gas cooktop. Your cooktop might be gas instead of electric. if so, then that does not require any waiting until 9PM.
And again as a reminder, none of this matters on weekends or holidays, because the time-of-use billing only makes a difference on Mondays through Fridays that are not holidays.
So what does make sense to try to do?
The electric clothes dryer. Yes, if it is a week day, avoid running the electric clothes dryer between 5PM and 9PM. If you are getting ready to buy a new electric clothes dryer, make absolutely sure you select one that has a “delayed start” feature that lets you delay the start of the drying process until 9PM has arrived. If your existing electric clothes dryer already has the “delayed start” feature, learn how to use it so that you can avoid running the dryer between 5PM and 9PM. But if the clothes dryer is gas, the time of day does not matter.
EV charging. As for charging up your EV, yes the smart thing to do if it is M-F is to avoid doing the charging between 5PM and 9PM. There might be either of two ways to do this. A first way is that your EV charger might be programmable to pay attention to the time of day and the day of the week. A second way is that your EV may be programmable to pay attention to the time of day and maybe the day of the week.
Of course the situation that will come up every now and then is that right now today you have some particular urgent need to charge up your EV even though it is during peak time (5PM to 9PM M-F). If so, then there is always some way to do it. With some EV chargers the way to do this is to plug the charging plug into the charging port of the car, and and then briefly pull the plug back out, and then plug it back in. This will tell the EV charger “yes I want to charge right now even though it costs more money”. And then you will hear a click from the charger as it turns on, and then the blinky lights on the car and on the charger will tell you that indeed the charging has commenced despite being more expensive.
Other appliances? What about all of the other things around the house that fall somewhere between these five big loads (air conditioner, electric oven, electric clothes dryer, EV charger, electric cooktop) and an LED light? Should you worry about time-of-day billing for those other things? For example what about a clothes washer? What about the dishwasher? What about a television? What about the refrigerator?
The main thing is that most of these things are more energy efficient than their counterparts from ten or twenty years ago, and most of these things actually use much less electricity than one might think. For one example, it is pointless to go out of one’s way to postpone turning on the TV until after 9PM. The monetary consequences of watching the TV for an hour during peak time (between 5PM and 9PM M-F) instead of waiting until 9PM to watch the TV for that same hour are (in my view) negligible — on the order of one cent on the electric bill.
Clothes washer. Yes if your clothes washer happens to have a “delayed start” feature, and if the day is a weekday, and if you are loading the washer between maybe 4:30PM and 9PM, you might as well use the delayed-start feature to postpone the start of the washing activity until 9PM. If it is a weekday and if your clothes washer lacks a “delayed start” feature, then you might as well wait until 9PM to press the “start” button. But the amount of electricity that the washer uses is much smaller than the amount of electricity that the electric dryer uses.
Dishwasher. Yes the dishwasher does use some electricity, but not nearly as much as the “big five” loads enumerated above. Yes if it is a weekday, you might as well try to postpone the start of the dishwasher until after 9PM.
Refrigerator. There is no reason to do any particular thing about the refrigerator so far as time-of-use billing is concerned. First of all, the refrigerator is probably much more energy efficient than its counterpart from ten or twenty years ago. Second, it is not like there is anything you could do about this. Should you avoid opening the door of the refrigerator between 5PM and 9PM? No! That will not change your electric bill by even a hundredth of a cent.
Electric oven and electric cooktop. This leaves two big-load appliances (the oven and the cooktop) to worry about. Again they might be gas appliances instead of electric, in which case the time of day does not matter. But if your oven or cooktop is electric instead of gas, then yes it will save some money on your electric bill if it is a weekday and if you avoid using it between 5PM and 9PM. But maybe you need to cook dinner! I think of this as a matter of personal choice. And maybe the meal falls on a weekend or a holiday in which case the electricity is cheap anyway.
Battery storage. If your house has battery storage, then you can probably configure your battery storage system to pay attention to time-of-day billing. For example you can probably configure it so that you never purchase any electricity during expensive time (5PM to 9PM M-F). If you do this, then the house runs on the battery during expensive time. And then the battery system will recharge starting at 9PM when electricity is cheap again. This saves money on your electric bill, and it is good for the environment.