Fluctuations in electricity use while we are on vacation

Question

We went on vacation for two weeks recently and I noticed that our PG&E bill had some unusual behavior.

• Our overall bill wasn't that much lower than it was when we were home.
• Different days had very different amounts of energy use. One day (63 degrees average temperature) had 5 kWh of energy usage and a few days later (65 degrees average temperature) PG&E reported 15 kWh of energy usage.

What could cause such fluctuations in our electricity use? We closed the windows and blinds and unplugged most disposable electronics except the TV (which was turned off), refrigerator and a small Coway air purifier (left on by accident). The refrigerator was installed within the last five years.

A smart home app sends alerts any time the doors open or close, and it did not fire for the entire vacation, so there's no chance family members or kids were secretly home.

We have a gas heater, no A/C and the we set the thermostat to "eco mode" = 50 degrees = while we were gone.

edit Here's a photo from the low energy day, 5kWh of energy use:

And high energy usage - note the different scale on left hand side.

No one was in the house on either of these days.

Answer 1

Do you have any electrical convenience outlets on your house ? While your home's inside is secure, what about the outside ?

I would look into the possibility of the above.

Answer 2

You say, “Energy Use”, but really it’s your electrical use you’re concerned about.

The item that uses the most energy in any home is the heating/cooling. However, you indicate that you have gas heat and no cooling. Therefore, that would not affect your electric bill whether you’re on vacation or not.

The second most energy user is usually the water heater...which is affected by laundry, bathing, dishes, etc. Not doing these activities could significantly reduce your electric bill.

Cooking is also something that uses a significant amount of electricity...oven, toaster, crockpot, etc. If you don’t use these a lot normally, then you would not see much change when on vacation.

Last is lights, chargers, etc. These use minor amounts of electricity, so no use when you’re on vacation would not reduce your total cost by much...

I would focus on checking the water heater. If it’s cycling on and off it could affect you electric bill the most.

It’s curios how the utility knows how much energy you used each day...did you get a printout of you daily use? Is this normal getting this from your utility?

I’d expect my electricity use to be fairly consistent day-to-day when no one is in the house for two weeks. (Do you suspect teenagers giving your security access code to friends and neighbors?) Is there anything on a timer, like pool heater, sauna, roomba, etc.

Answer 3

Check to see that each day is separately accounted for during your vacation. Dashboards read smart meters once a day, usually around midnight and compare that reading to the day before to get the daily usage. If, for some reason, they don't read it on a particular day, which does happen due to computer problems, etc., the next day's reading will appear to be twice as much. Sometimes they will go back and correct it but not always.

Answer 4

There's no way anyone could have guessed this, but FYI, I discovered that our meter was reading the usage from our upstairs neighbors apartment, and their meter was reading the usage from our apartment.

The reason the energy usage was high was because we were being billed for the usage of our upstairs neighbors, who were still home and running the laundry and dishwasher while we were on vacation.

You can verify this (with PG&E at least) by comparing the meter number on your bill to the meter number that corresponds to your apartment. If they don't match, you may be being billed for someone else's usage.