Odd mix of new and old meters in the meter cupboard.

[JohnW2]

In that case, get rid of the dual rate / economy 7 completely and change to a single rate tariff.
It will be significantly cheaper ....

I agree that, in the absence of night storage heaters, it is almost always going to be cheaper to have a single tariff. However, as I've pointed out before, that's not inevitable, so it's probably worthwhile looking at one's individual circumstances before deciding to get rid of a dual tariff, even if one doesn't have storage heaters.

I am probably extremely atypical. However, as the below graph for the past year shows, with cheap-rate electric water heating and given our semi-nocturnal lifestyle which enables most high-load appliances (WM, DW, Dryer) to be used at cheap rate, we generally manage to maintain 40%-50% of our usage at cheap rate. With the financial break-even point being about 35%, the effect of this pattern of usage is that our electricity bills are 10-20% lower than they would be without the dual rate (in our case, E7) tariff. (The dips down to low cheap-rate % relate to days/periods when daytime usage was high {usually because of visitors} - which can be seen most dramatically over the recent Christmas period)

Kind Regards, John

 

[pieceofmind]

Are you gathering this information manually, or is there a quicker method?

 

[JohnW2]

Are you gathering this information manually, or is there a quicker method?

My energy usage is monitored automatically, 24/7. The above graph (and many others) is derived from the resulting stored data, which consists of measurements taken roughly every 12 seconds - although the graph above obviously relates to day and night totals on a 'per day' basis.

Kind Regards, John

 

[pieceofmind]

Hi John, What are you using to monitor usage? Cheers, Mark.

 

[JohnW2]

Hi John, What are you using to monitor usage? Cheers, Mark.

The actual monitoring system is 'Owl Intuition-LC', which uploads the ~12 secondly data to the OWL website, from where I download it every day or three (it's stored there for at least a month, I think about 3 months).

This system uses clip-on sensors on the meter tails. That's not ideal, since it means that it only measures current, not voltage or phase, and therefore measures KVAh, which can only be converted to KWh by assuming a (constant) voltage and a (constant) power factor. However, it is more than adequate for my purposes and, despite the shortcomings I've mentioned, has produced results extremely close to those of my supplier's electricity meter (which measures true kWh, constantly taking voltage and PF into account) - I'll see if I can find the graphs that demonstrate that!

Kind Regards, John

 

[pieceofmind]

That's great, thank you!

 

[JohnW2]

That's great, thank you!

You're welcome.

... However, it is more than adequate for my purposes and, despite the shortcomings I've mentioned, has produced results extremely close to those of my supplier's electricity meter (which measures true kWh, constantly taking voltage and PF into account) - I'll see if I can find the graphs that demonstrate that!

Here you go ... separately for day and night usage, a comparison over the past couple of years of my cumulative usage as indicated by my supplier's meter (true kWh) and the OWL system (kVAh, converted to kWh with assumptions about voltage and power factor). As you can see (and despite what some might expect), they are as identical as makes no difference!

Kind Regards, John

 

[pieceofmind]

It's accurate enough then!

 

[JohnW2]

It's accurate enough then!

Indeed so - more than accurate enough for my purposes (probably almost anyone's purposes!), and almost perfect. Over the period of those graphs, the totals for meter and OWL were 8336 and 8344 kWh respectively during 'day' (<0.1% difference) and 7830 and 7833 during 'night' (<0.04% difference).

I already knew that my average supply voltage was about 240V, and sticking with that figure throughout seems to have worked fine. For the first few months I had to keep my eye on the power factor I was assuming, and tweak my calculations appropriately, but eventually settled on 0.940 for 'day' and 0.978 for 'night' (very high, since night usage is dominated by immersion heaters, which are virtually pure resistive loads, hence a PF of ~1.000) - and I've now stuck with those figures for well over a year.

Kind Regards, John

 

[SimonH2]

In that case, get rid of the dual rate / economy 7 completely and change to a single rate tariff.
It will be significantly cheaper and the timer can be removed.

It may be that the house is already on a single rate - but the supplier doesn't want the cost/hassle of going and removing anything. All they'd need to do is set the rate for both registers to the standard single tariff rate.

 

[pieceofmind]

It may be that the house is already on a single rate - but the supplier doesn't want the cost/hassle of going and removing anything. All they'd need to do is set the rate for both registers to the standard single tariff rate.

Good point! I presume it would be broken down on our bill?

 

[JohnW2]

It may be that the house is already on a single rate - but the supplier doesn't want the cost/hassle of going and removing anything. All they'd need to do is set the rate for both registers to the standard single tariff rate.

Non-smart meters don't know anything about tariffs/rates - they simply tot up the number of day and night units separately.

When people move from dual to standard tariff, it would certainly be possible (and very simple!) for the suppliers to leave the dual-rate meter in place and simply add the night and day figures together for billing. However, with virtually everyone I know (quite a few) who who has made such a change, the supplier has, for some reason, insisted on changing the meter for a single-rate one - despite, in many cases, the customer pointing out to them that this was not really necessary. Go figure!

Kind Regards, John

 

[ban-all-sheds]

I blame the computer.

 

[JohnW2]

Yes, the computer probably "says no"