Energy monitoring plug has just arrived - now what?

ChasingtheWelshdream

Morning’ All,

Inspired by the people on here who have made savings with their electricity, I have just bought an energy monitoring plug in my own quest to vanquish any hidden vampires and generally make savings.

It is a TP link Tapo smart plug. I’ve downloaded the app, connected it up and it is now merrily blinking away at me, informing me that my phone is using 6.8w whilst it charges.

Which is all very nice, but I now don’t know what to do with that information.

I intend to move it around the various electronics (3 kids, wfh, lots of gadgets and appliances) and work out how much each is costing per hour/day.

The instruction leaflet told me to follow the instructions on the app, but doesn’t explain how to make the most of it.

Would someone kindly (and simply) explain how I can calculate the cost of running a gizmo using the plug please?

Also, it shows current power and total power for the 7 days. If I move it to different gadgets, does that need to be reset?

Thank you!

[Deleted User]

For something that always uses about the same amount of power (like that phone charger):

Power = 6.8 W

Energy of using this for 1 hour = 6.8 x 1  = 6.8Wh (0.0068 kWh because 1kWh is 1000Wh)

Cost of 1 hour = energy used x your unit price (for example 50p/kWh) = 0.0068 * 50   = 0.34 pence for the 1 hour.


For something where the power changes (like a fridge freezer), you're better using the kWh numbers from "Today"

Look at how much the "Today" number changes over 1 hour (or 4 hours, or 8 hours...)

Then skip straight to the cost line of the maths above, because you already know the energy number.

Astria

What there plan is, is that you purchase multiple plugs for multiple gadgets/devices. So yes you'll need to reset the stats for multiple devices on the same plug.

Remember 1 kWh = approx 50p in October, so if a device used 1000 W for 1 hr then that's 50p. If it uses 100W for 1 hr then 5p, 10W = 0.5p, and so on. If it uses 1000 W for 30 mins, then 25p. So a kettle @ 3000W for 1 minute is typically 3*50p / 60 = 2.5p.

uksitebuilder

Yes, the app could be better and a reset button would be great, but it's workable

The_Hawk

It all depends on how you use the device you are monitoring.

This is how I've gone about it:

If it's something like a fridge-freezer, that's running all the time, I'd connect for, say, 3 days (the longer the more accurate it is likely to be), then take a usage reading, divide by the 3 days and multiply by 365 and that will give me a rough idea of my annual cost.

For a tumble dryer, which is an on-off device, I'd take a reading before and after a few different types of loads to get a rough idea of an average cost per load. I'd also note the time the tumble dryer was running for each load. Once I'd got an idea of the cost of an average load, I can multiply up by the typical number of loads per week/month/year to get an idea of the annual cost.

The Tapo P110 is excellent for the price, but it does have one flaw, the app has no reset button to set the total back to zero, which leaves you with two choices:

1. Do a hard reset on the plug every time you want to 'zero' it; or
2. Note the start readings, before you connect it to each device, so that you can deduct these from the end readings.

ChasingtheWelshdream

Thank you so much all, that is really helpful! 

Yes, I saw the recommendations to buy multiple plugs, but in MSE style I will save the pennies and take the long term approach.

I am just playing with it today and am going to set up a spreadsheet showing everything and (hopefully) how much savings we can make.

So I have plugged it into the fridge freezer and have been fascinated how the usage fluctuates when the door opens. It was only on for a short while, but how would I read the chart if it had been on for a couple of days? In this snapshot, the current was 207.5 - is the 124 on the y-axis the average?

Sorry if it is a silly question!

dunstonh

I have 3 of the P110s and have another 4 on the way whilst they are on special price at Amazon.

Information is how you learn about your use.    These plugs help you gather information but they don't give the whole picture. 

First of all, you need to know how much electricity you use each day.  You can get this from your smart meter, if you have one, or you can get devices, such as the geo minim (which is what I have)  https://geotogether.com/product-category/energy-monitors/

Once you know your daily usage, you can then use the P110s to initially work out what your devices are using and how much they contribute to your daily use.     It may be that you find out some devices are using a lot of power and that replacing them with a new device is more economical.  For example, we found replacing our FF with a new one would knock off 2kWh per day. That is over £1 a day (heading towards £2 a day in the new year).  However, at £1.10 a day, that is £401.50 a year.  The new FF was £1600, which is a breakeven point of under 4 years at current rates.   Our old daily use was 18kWh per day and through a few new purchases, no longer using standby and multiple P110s allowing easier control of hard to reach switches, it has got to 9kWh per day.  That is £5 a day saving.   Not a lot when you say £5 but multiple that over the year and consider next years rates, then its big saving.

The monitoring side of the plug is a pain doesn't refresh in real-time.  You have to flit between the pages on the app and back again to see the current power use refreshed.  (I press schedule and then back).  However, it is sufficient for you to see how current use is trending.     Items like TVs often have power options (such as standby light, quick start and mobile device connectivity).  These use power if enabled.   So, you can see the differences if you disable those options by looking at the app before changing settings.

A lot of people use their TVs with high brightness and/or contrast.  Often on the default setting that is used for display models in brightly lit showrooms.  Not in darker lounges.   You should look to lower those settings for a better picture and it happens to save energy as well.   The tapo can help you see what difference it makes.

Microwaves on standby shouldn't use much but people have found that they are drawing 20+w for having a clock on display (often flashing as it hasn't been set).    Turning it off at the switch solves that problem but not all kitchen switches are easily accessible.   So, the tapo can become useful there.    

uksitebuilder

The way I do it for leaving a device plugged in for extended period of time is to note down the usage for the last 12 months (seeing as I only recently purchased it myself) - This is the starting total

Plug in and leave for a day or two

Grab new total from the 12 months total and subtract the previously noted figure.

Should give you the usage for whatever time your have been testing.

It's a pain for me to fully reset the device due to my router being 5ghz/2.4ghz  device and needing to turn off 5ghz to initially connect this device. But if more testing is needed next year I will have to do that I guess. Although this plug may well be somewhere else by then or in the niknak draw with everything else you keep and never use again

ChasingtheWelshdream

Thank you, that is really useful. Yes, I need to establish our base usage first
and then see how/where we can save. We have an extremely high estimated annual usage based on previous years, when we had an ‘always on’ electric range. We recently got rid of this but now need to establish and estimate where we are going forwards. I am quite looking forward to seeing the before and after

dunstonh

ChasingtheWelshdream said:

Thank you, that is really useful. Yes, I need to establish our base usage first
and then see how/where we can save. We have an extremely high estimated annual usage based on previous years, when we had an ‘always on’ electric range. We recently got rid of this but now need to establish and estimate where we are going forwards. I am quite looking forward to seeing the before and after

If you have access to your meter reading history (many suppliers show a long history) then you can rebuild your use.  I take a meter reading on the same day each month and put it in a spreadsheet that gives me the following:



I can see how much my day, night and total use is and how it compares over the years. I have a notes column on the end to note any month where usage is out of the norm.  We have an electric AGA which draws 7 hours of power a day which makes eco 7 viable.   Its only on for around 9 months of the year (maybe only 1-2 months until prices normalise in 5-6 years time or my solar panels make a sufficient difference).  I can tell from my readings that I averaged 18.58kWh per day from  10th June to 10th July and 18.47kWh in July/Aug   So, you can find your use from your meter readings, log it and then equate it to daily use during that period.

ChasingtheWelshdream

That is extremely useful, thank you!