Turn off Fridge During Peak Elec Rate Period?

[TromboneAl]

Here are the electric rates in PG&E's Time of Use plan:

Seeing that, what frugalista could resist trying to game the system?

From our frequent power outages, I know that our fridge can be off for hours at a time without problems. The fridge is the single biggest user of power in the house.

So, why not set a timer to turn off the fridge from, say, 4 PM to 7 PM?

[Note that I realize that with a non-time-based rate, there would be no savings in shutting off the fridge.]

 

[Sarah in SC]

Very nifty! Let us know the results. I don't think our local electric utility does this, but you've got me thinking!

 

[REWahoo]

Al, do you have a Kill-A-Watt to measure usage? One think I'd want to know is does the run time required to bring the fridge back to normal temps after the time-out cancel out your savings, even at a lower rate?

 

[Nemo2]

And..if you open the fridge door between 4 & 7?

 

[Bigdawg]

I quickly looked up a few internet articles on food spoilage. Seems like if you have a lot of volume (bottled water, juice containers, etc...) then the temp will stay lower longer. Also don't open the refrigerator if possible. Many of the comments thought 10 hours would still be good.

I would expect to read this type of article on MMM.

 

[athena53]

Our power company gave us a freebie thermostat in return for being able to cycle our A/C on and off during periods of peak usage; they say that will happen maybe 3 times during the summer and the house temp might increase by 2 degrees. The thermostat is easily programmable from a smartphone, which means we can turn the heat to 55 degrees while away on a trip, then change the setting back to a more comfortable one a few hours before we get home.


Unfortunately, we don't get any price breaks for giving up some A/C during the summer (I suspect it just means that all customers benefit from using less power off the grid when it's most expensive), but I think the thermostat all by itself (plus savings from being able to set it remotely) was a good deal.

 

[Texas Proud]

WTF...


You pay 37.5 for peak usage!!! That is just not right.....


The problem that I would be concerned with is the difference between what happens to the food when this happens once in awhile (power outage) vs every day....

You know the temp is going up... but by how much? You know the food is OK with one day, but you will consume it before it goes through another 'warming' cycle.... if you do it every day, some food will go through many warming cycles....


What should be included is a set up/set back thermostat like we have for or HVAC systems... that way you could cool it down just before shut off.... and also have it programmed to turn on if it got too warm because of being used more than you thought...

 

[ExFlyBoy5]

I don't know that you would save that much. Odds are that the fridge wouldn't run too much anyway but then when it's been off for a while, it will have to run longer to "catch up". I definitely think it would be worth getting a "kill-a-watt" and you can have a reasonable answer in a day or two.

Also, are you able to get daily readings of your energy use? I am able to see the previous day's usage the following day...it has been very helpful to determine where to set the thermostat for optimum heating/cooling/saving as well as how much energy is consumed with other stuff (like a computer being left on vs. turning off).

 

[jazz4cash]

Our power company gave us a freebie thermostat in return for being able to cycle our A/C on and off during periods of peak usage; they say that will happen maybe 3 times during the summer and the house temp might increase by 2 degrees. The thermostat is easily programmable from a smartphone, which means we can turn the heat to 55 degrees while away on a trip, then change the setting back to a more comfortable one a few hours before we get home.


Unfortunately, we don't get any price breaks for giving up some A/C during the summer (I suspect it just means that all customers benefit from using less power off the grid when it's most expensive), but I think the thermostat all by itself (plus savings from being able to set it remotely) was a good deal.

We have a similar plan. We get $37/mo credit per month for permitting the utility to cycle the A/C up to 75% (45 minutes per hr). We could get a higher credit for permitting 100% cycling. The temp goes up by much more than 2 degrees here in the DC suburbs. It gets quite uncomfortable but not miserable. You can override the event 1 or 2 times per year if you are having a party or something. It's worth the hassle. We declined the smart stat since I prefer our dumb programmable ones.

 

[naggz]

What about taking some large empty bottles, and freezing water in them overnight, and placing them in the refrigerator during the peak times. The Ice packs may prevent the fridge from cycling on as much during the peak period, and you don't have to worry about food spoilage.

 

[jazz4cash]

I don't know that you would save that much. Odds are that the fridge wouldn't run too much anyway but then when it's been off for a while, it will have to run longer to "catch up". I definitely think it would be worth getting a "kill-a-watt" and you can have a reasonable answer in a day or two.

Also, are you able to get daily readings of your energy use? I am able to see the previous day's usage the following day...it has been very helpful to determine where to set the thermostat for optimum heating/cooling/saving as well as how much energy is consumed with other stuff (like a computer being left on vs. turning off).

+1
Since they installed smart meters, we can get hour by hour data for usage and cost.

 

[marko]

I suspect if you put some sort of mass (large water jug, heavy stone) that the thermal inertia would allow the fridge to coast a long time between runs.

Might be easier than turning off/on. I really don't see how a 3-4 hour turnoff will make any notable difference... a few cents at best?

 

[bld999]

What about taking some large empty bottles, and freezing water in them overnight, and placing them in the refrigerator during the peak times. The Ice packs may prevent the fridge from cycling on as much during the peak period, and you don't have to worry about food spoilage.

Great idea!
____________________________________________________________
I guess I have been ignoring electricity prices country wide. 21 Cents per kwh...? Holy Cow, Rates in Tacoma where my old mother lives are about 3 - 4 cents per.

 

[jazz4cash]

After studying the rate plan some more, it imposes premiums for both time of day and total usage. Do they disclose where the total use (Tier1, Tier2, etc.) levels are set? There's no units on the charts. I presume it shows cents per Kwh but can't tell if it is just for electricity or does it include fees and distribution charges. For comparison our total cost is .13-.15/Kwh. For the data I posted our total cost was about $0.45 from 4-7pm for the whole house.

 

[FUEGO]

Wow those are some high rates. I think ours are 9-10 cents per kWh on a flat rate plan and 6-16 cents on the on/off peak rate plan.

As far as cycling the fridge, I can't imagine a 3 hour outage from 4-7 would result in a high temperature gain. Maybe 5 degrees if you aren't opening it much? Food might spoil slightly quicker, but being at the target temp the other 21 hours of the day would prevent any significant increase in spoilage.

But is it worth it to save the 11.5 cents per kWh three hours per day for five months of the year?

 

[harley]

I think you'd save more money over time by moving somewhere that didn't charge usurious electric rates. That's ridiculous! Since you're a biker, maybe you could hook your bike up to the grid and pedal enough to keep your refrigerator turned on.

 

[ERD50]

If I read it right, you are talking about ~ $0.115/kWh delta from the pre 7PM rate until after. So you'd basically shift three hours ( 4PM -7PM) to post 7PM.

Overall electrical usage will be pretty much the same, I understand you just want to take advantage of the time shift. Get a Kill-a-watt meter on there for the 4PM to 7PM time frame for starters. I'd expect a reading around 120 watts average. If that's close, that is ~ .360 kWh/ day, so ~ 11 kWh/month, or ~ $1.25 per month.

Is that worth it (cost of a timer)? I'd also be concerned that doing this every day would mean sometimes interrupting the defrost cycle, and also shutting the compressor down just after is started. That might add wear and tear, that would not be noticeable with the occasional power outage.

Move frozen jugs from freezer (~ 0F), to the fridge at 1PM, move them back after 7PM. That will cause the fridge to run less, but on a normal cycle, and the chilling of the bottles will occur at the lower kWh rate.

But that does not sound like it is worth the effort either. Go find something fun to do instead.

If you have an ice maker, disconnect it. That is a big juice eater.

-ERD50

 

[NW-Bound]

According to a Web site that I just consulted, a modern 25 cu.ft. Energy Star fridge uses 60 kWh/month. That's 2 kWh/day, or 0.5 kWh average for the 6-hr period between 1PM-7PM where the rate is the highest at 37.5c/kWh.

If one can somehow shift this 0.5 kWh to the cheaper period where the rate is 26c/kWh, he saves 5.75c/day or $1.73/month.

Of course you would save more if your fridge is an older energy hog, but then such a fridge would likely have poorer insulation and warms up more during the 6 hours that it is off.

 

[meierlde]

According to a Web site that I just consulted, a modern 25 cu.ft. Energy Star fridge uses 60 kWh/month. That's 2 kWh/day, or 0.5 kWh average for the 6-hr period between 1PM-7PM where the rate is the highest at 37.5c/kWh.

If one can somehow shift this 0.5 kWh to the cheaper period where the rate is 26c/kWh, he saves 5.75c/day or $1.73/month.

Of course you would save more if your fridge is an older energy hog, but then such a fridge would likely have poorer insulation and warms up more during the 6 hours that it is off.

Good catch, the first thing to do if the fridge is old is to get a new one. I was checking a bit and found a 25 cu ft unit that draws 474 kw/year, which works out to 1.29 kwh/day or for your 6 hour period .32 kwh, so at an 11 cent difference you save for this model 3.2 cents a day. or over the year 11.68 or so. So not really worth it. The first thing to do does involve capital spending to go to the most modern units in fridges and HVAC. If you have timed thermostats, you can set them in an unusual pattern and take the temp down in the morning, setting it up between 1 and 7 pm.
I replaced a 26 year old unit with a new unit and have seen a difference in the electric bill because of it.

 

[NW-Bound]

That peak electric rate of 37.5c/kWh is even higher than that of Hawaii at 33c average.

A Web site says the average rate for CA is only 15c. What is special about T'Al Northern Coastal CA?

 

[NW-Bound]

When the electric rate is this high, one should consider solar power.

In Northern CA, a 250W solar panel will provide about 1.5kWh/day in July. Taking the average between the 26c rate for 10AM-1PM and the throat-cutting 37.5c for 1PM-7PM, that 1.5kWh works out to 47.6c/day. It is roughly $15 worth of electricity a month.

The above solar panel costs about $250, and will need a grid-tie inverter costing another $250. The return on this equipment (ignoring other costs) is 3% in July alone.

 

[target2019]

Thermal blanket. Cover the fridge during peak period with insulated blanket. See if that impacts the bill.

If your fridge is biggest power hog, that seems odd to me.

 

[ERD50]

When the electric rate is this high, one should consider solar power.

In Northern CA, a 250W solar panel will provide about 1.5kWh/day in July. Taking the average between the 26c rate for 10AM-1PM and the throat-cutting 37.5c for 1PM-7PM, that 1.5kWh works out to 47.6c/day. It is roughly $15 worth of electricity a month.

The above solar panel costs about $250, and will need a grid-tie inverter costing another $250. The return on this equipment (ignoring other costs) is 3% in July alone.

It might make economic sense to angle the panel towards the West for May-Oct, to maximize the 1PM-7PM output, and sacrifice some overall.

Or do they change the rate if you install solar?

-ERD50

 

[samclem]

If one can somehow shift this 0.5 kWh to the cheaper period where the rate is 26c/kWh, he saves 5.75c/day or $1.73/month.

Of course you would save more if your fridge is an older energy hog, but then such a fridge would likely have poorer insulation and warms up more during the 6 hours that it is off.

I wonder if refrigerators/freezers will/already do come with timer/thermostats so they can help reduce energy use during peak rate periods?
-- Drop the temp in the 'fridge a few degrees just prior to the start of the peak so it can coast through the peak period without turning on (I can see the lettuce freezing already!)
-- Accelerate/delay the defrost cycles in the freezer so they don't occur during the peak period
-- Actively move the air from the freezer section to the fridge to keep the fridge within the desired temp range. This way the freezer serves as a "cold bank" for the fridge.
-- A modest, subdued, tasteful "chime" when the door is opened during the peak rate period to serve as a reminder to get the door closed without delay.


Obviously, the fridge comes on regardless of the utility rate if the temps threaten to go out of a safe range.

Ironically, none of these steps would save energy, they would actually increase energy use. But they help with this little game.

 

[audreyh1]

Here are the electric rates in PG&E's Time of Use plan:

Seeing that, what frugalista could resist trying to game the system?

From our frequent power outages, I know that our fridge can be off for hours at a time without problems. The fridge is the single biggest user of power in the house.

So, why not set a timer to turn off the fridge from, say, 4 PM to 7 PM?

[Note that I realize that with a non-time-based rate, there would be no savings in shutting off the fridge.]

I think this may be unique to your cool West Coast area, as I doubt you run A/C often, you might not even have it. Maybe your heating doesn't consume electricity.

Most of the rest of us heating and cooling dominate our electric rate.