Economy 7 Electricity with a Smart Meter from Eon-Next (Toshiba EDMI, SKU1 Cellular)
(NB: It’s the same as the one that NPower used to install before Eon-Next took it over.)
On 8 June 2021, a SMET2 Smart Meter was installed by Eon-Next for my studio flat. I had been waiting to be offered one of the latest meters because the old SMET1 ones aren’t guaranteed to work when you change supplier and I do tend to change every year! The meter transmits it’s readings to a remote monitor inside my flat thus providing me with a record of the kilowatt hours (kwh) of energy used each day together with the estimated cost which takes into account my Economy 7 tariffs of 11.44p/kwh for night, 22.31p for day and 7.35 for standing charge. Given the number of kwh used for a day and its estimated cost you can use simultaneous equations to work out how many kwh were used at night and how many kwh were used during the day. I have encapsulated this within my Electricity.xlsx spread sheet so that now instead of going outside at 08:45 every day to record 2 meter readings, I simply record from the remote monitor at any time after 08:30 every day the number of kwh used yesterday and its estimated cost.
I couldn’t find any mention of two metre readings on the Smart Meter so this made me think that although a Smart Meter doesn’t actually calculate your bill – as mentioned on the Internet – it does provide an estimate of the bill from which the suppliers computer system can calculate the actual bill that they send you!
A Smart Meter makes it unnecessary for you to provide the supplier with readings because it sends monthly readings to a central computer system via the SMWAN run by the Data Communications Company (DCC) set up by the government to manage Smart Meter communications on behalf of suppliers. It doesn’t use the Internet – it uses mobile phone technology.
The suppliers computer system interrogates the DCC computer system to get your readings to calculate your bill each month. You can ask them to collect your meter readings daily rather than monthly if you want more details for analytical purposes.
Apart from saving you having to go outside and read your meter, the remote monitor can be used to show how much energy is being used at each moment during the day. You can carry it around on battery power and switch your electrical devices on and off to find out how much each one is using. However, for most of the day it has to be plugged in to keep it charged up.
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SMART METER SIMULTANEOUS EQUATIONS
KN + KD = KT
KN * RN + KD * RD + RS = CT
Where
KN = Kilowatts Night
KD = Kilowatts Day
KT = Kilowatts Total
RN = Rate Night
RD = Rate Day
RS = Rate Standing charge
CT = Cost Total
So
KN * RN + (KT – KN) * RD + RS = CT
KN * RN + KT * RD – KN * RD +RS = CT
KN * (RN – RD) + KT * RD + RS = CT
KN * (RN – RD) = CT – KT * RD – RS
KN = (CT – KT * RD – RS) / (RN – RD)
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However, it turns out that the kilowatts used for day and night are recorded on the Smart Meter. I discovered this when I finally managed to find on the internet this which includes how to read my meter for the Economy 7 tariff!
The above link should take you to the section which begins:
If you have two white buttons with arrows and other markings around them
However, I have revised the instructions that appear after that for the purposes of reading my meter:
- Press & hold the right button for OK to display the menu screen
- Press the right button until you see Billing
- Press & hold the right button for OK
- Press the right button until you see Advanced
- Press & hold the right button for OK
- Press the right until you see TOUmtrx
- Press & hold right button for OK
- The R01 reading should now be visible which is the register for day KWs
- Press the right button to see the R02 reading which is the register for night KWs
NB: You can press and hold the left button to go back