New Smart Meter + new HHRs + old 3-rate, 2 MPAN tariff = Confusion

rglynt

Hello all,

Green-as-grass newbie here, though I’ve read a few related threads over recent months. Lots of good info but my situation doesn’t quite match any scenarios I’ve seen, hence new thread. If this belongs on an existing thread please point me to it & I'll delete this

So: I’m a ScottishPower customer in SE Scotland. All electric, small 3 bed semi. Until early summer I had an old meter and old Dimplex SHs which worked fine (and cheaply - I suspect that I was being under-metered but that’s history now…). Charged overnight only. Since then I’ve had:

1) A Smart Meter replacement, at 2nd attempt. 1st installer couldn’t deal with my <Complex> setup. (Meant nothing to me then..) 2nd installer got it working (at the cost of timed DHW, which he said the new meter couldn’t handle). Clara SGM1422B, 5 tail.

The SHs immediately started charging during daytime. I’d turned one on early AM to check it was charging (or at least the wall socket was lit), forgot about it when it went off at 7.30, went away for the w/e and came back to a hot house and a big ‘week to date’ total on the meter remote. This kicked off a long and frustrating dialogue w/ Scottish Power (see below).

2) An ECO4 upgrade: PV, Elnur HHR ECO20 SHs. HHRs on 2 supplies, OP and Peak wall sockets. Barely used until recently, programming played with a bit, OP wall lights still coming on c3PM, consistently.

Trying to get SP to explain what’s going on has been tricky, because they didn’t seem to know either. Very short version: as of a week ago, they say that I’m on "ComfortPlus White Meter with Weathercall Option”, and the PM charge availability is a function not of a split OP period but of forecast weather/temperature. I’m skeptical given that the timings haven’t shifted between early August and now, but that’s their position. 

So in summary, I seem to have:

- A 2-MPAN meter system serving a 3-rate legacy tariff designed for dumb and by implication under-specced SHs with no controllability beyond input and output dials, combined with

-A smart meter and fully programmable HHRs designed for user control and optimisation.

-Charging on Control rate which is substantially higher than OP rate (currently c 22p vs 16p)

To get a handle on the HHRs I’m currently charging 2 of 3 (LR & Hall) for 3 hours only, with 18c target temp they’re keeping room temp at 17c+ until my 10PM-ish bed time. Meter remote says they’re drawing c1.9kW each, so hardly crippling but it’s still v mild and Winter Is Coming….. 

I’m trying to get SP to state clearly what my options are - are 2MPANS a physical necessity for any SH-based system, can I switch to a 2 rate tariff and get 2nd MPAN deleted, etc. I’m sick of them and would rather switch supplier, but I’m aware that Complex setups scare some suppliers away.

Hope this makes some kind of sense, any observations / advice / questions welcome. The last time I spent this much time worrying about leccy I was living off grid and depending on PV, wind and batteries…...

Scot_39

Their are or were multiple SP white meter tariffs - brief summary here

https://www.scottishpower.co.uk/energy-efficiency/energy-efficiency-toolkit/electric-heating

Do you know what specific tariff you were on before the smart meter upgrade on the old meters.

From that list "ComfortPlus White Meter with Weathercall Option" was supposedly a single meter solution - and as I read that summary page  (but worried its not a completely accurate description for some of those tariffs)

1) Normal lights and sockets - live 24.7 charged at day rate / night rate

2) Restricted (time limited) special heating circuits - like your off peak NSH - charged at comfort rate - time limited

(weathercall was dynamic - the off peak period changed based on forecast weather )

The non weathercall had changed for some to be 7.5 overnight plus 1 hour afternoon.

The new smart meter you have - if its an Aclara SGM-1422-B - is a fairly unique device for UK single phase metering.  More than needed for say a standard E7 install.  There's a whole thread on the fun an EDF customer is having with theirs.

It has what is technically known as "twin element" functionality - for measuring energy use.

Basically it can measure port 4 output (say your normal circuits live 24/7 on day / night rates) and port 5 (in your case from the SP web description I would expect to still be time restricted I suspect for your NSH) feed to the NSH seperately  and so bill again at 3 rates.

I dont understand why the HW tank would be treated differently - before / after - except often night charge at E7 style off peak could be cheaper and last the day for most folk.

So it can actually replicate the weathercall - or at least the non dynamic hour version of it - without them constantly downloading new timings OTA .  To differentiate between off peak night and comfort circuit rates.

The rates themselves probably have not changed - just the device way of measuring them and controlling them.

(A standard E7 meter doesn't do that - it just measures the total energy through the meter - the total to both ports when active. So a standard modern E7 has 2 rates that apply to whole house - and when tied with meter ALCS timing controlled NSH  HW tanks - the off peak and their activation should be synchronised - so charged at the off peak)

In fact some at EDF with that meter - have (or had when last checked the thread) 4 readings available - 2 for port 4 24/7 live - and 2 for restricted port 5 (even if one ideally should always be zero - it wasnt in their case).

It's unclear why your NSH have been charging during the day window.

There are possible meter configuration or wiring changes that have also gone on - that might explain soe of the issues.

You could delve into the meter / logs - and see if you can see switch timings - or simply keep your eye on the little contactor symbols on the actual meter - or in your case as have them - the NSH spur switch LEDs that tell you the input power is live.

Re the new Elnurs - these work a little differently from your old box of bricks - and ship with a requirement to take an initial charge to 80% on power up.

So that would be rating x 7hours x 0.8 per active device (they tend to base charge capacity on 7 hours as thats what most in UK get on E7).

They will do that on the first power up - and then they use an adaptive system to adjust that target - so right now - would hopefully be taking less the second day / night etc.

Also the new Elnurs come with a need to set the charge times - the default to one common regional E7 timing (00 - 0700 iirc) so these ideally should be set to match your meter comfort rate tariff times.

Did they leave you an instruction manual - have a look in the installation section for the parameter list.

Ive linked it in another thread recently if not.

rglynt

Hi & many thanks. 

The HW is just one of many baffling aspects! I can get a timer fitted & don't use much so it's a 2nd order problem.

Yes, I've read up quite a lot on SP tariffs & Elnur operation.

The only 3 Register tariffs for S Scotland are C+WM w/ or w/out Weathercall. What I had pre-switch I don't know. Billing makes no mention of latter and I can't square the very consistent energised hours with the supposedly dynamic timings thereof, whereas I can w/ former, which as you note specifically mentions fixed overnight & PM boost periods. (The SP complaint handler admitted he's new to the job & was flailing, and a week ago literally wrote "ignore everything I've told you over the last months". So he could well be wrong, again...) 

From comments on these & other boards on the Elnur I've lowered target temps, zeroed the balancing and set the (short 3hr) charge period squarely in the middle of the night. By 7.30 core temp is c150c. I know they'll need more juice come the cold weather. I think I have a handle on their operation.

Tariff options & underlying technical constraints, not so much!

For one thing I don't honestly understand whether or not the smart meter & programmable HHRs I now have physically require a separate switched supply & associated MPAN. I assume, perhaps naively, that they could run perfectly well on a 2 rate, 1 MPAN  "Economy  X" setup, hard to get a straight answer from SP. Their position in essence is "you have heating, you have HW, suck it up". Back in the day Control rates were apparently at or below OP rates, with the aim as I understand it of giving the suppliers an additional load balancing lever. No longer the case, so if I'm stymied in looking for cheaper tariffs elsewhere by the complexity of this system and the consequent reluctance of other suppliers it may get costly. 

I'm drafting an email asking them for clear unambiguous answers, so we'll see. Time to walk the dog and clear my head!

Rgds R

QrizB

Your Elnur HHRs are designed for E7. If the ECO4 people did their heat loss calculations correctly, the should be sized for E7 too.

It might be simpler to ask SP to switch you to E7, although I don't know enough about your current tariff rates and your likely consumption on each register to say whether E7 would save you any money, or not, but it would definitely simplify things.

Scot_39

You may not want to set the balancing element use to zero hours (the installation parameter Px value ranging upto 5 (hours) iirc by default) - as it turns off the auto charge adaptation - so the heaters wont track you use and seasonality as well as they might.

Its a bit strange as it looks like a way of forcing you to use upto an hour (5 hours by default) of low power admittedly (c1kW on the 40 vs 3.4 kW main charge iirc) but at peak rate on E7 or day rate I guess in your case.

(Note I dont have Elnurs - but was warned by a user before the warning added to some versions of the manual not to set to zero hours for that parameter for that very reason.  I looked at them as an alt for Quntums - but they only cope with 2 off peak slots a day and I have 3 on my E10.)

rglynt

Thx again.

The ECO4 crew seemed to be pretty thorough in surveying & calculating. God knows they did a lot of installations hereabouts! I'll certainly be asking SP to clearly set out my 2 rate options & rates. 

As I said, I don't really get why the 2 MPAN, 3 rate config was carried over but at the time they didn't explain and I lacked enough of a clue to ask. AFAIK the entire rationale for the former disappears with smart meters & heaters installed? 

And yes, I read conflicting advice wrt balancing element, may enable 1 unit for 1 hour and see how if at all their charging diverges. Installation co appears to be "all Elnur", whether for commercial or tech reasons I know not. 

Rgds R