IHD (in home display) wildly inaccurate, is this normal?

[ericmark]

I have made a mistake, thought my low tariff was midnight to 8 am and it seems midnight to 5 am, so I was checking the IHD to see if this time I had got it right, the app does not show £ it says "no data available for this time period" and the actual meter only shows total since fitted so "Rate 01 Act imp 00433 kWh" tells me nothing.

So waited until 3 minutes past midnight and looked at the readings on the IHD, 5.1 kWh, £0:00, of which of which 59.3p is standing charge is included. Clearly that is wrong. Waited a bit longer around 25 minutes into new day, and no charge. At 0:30 the battery starts to charge.

In morning looked again 3.49 kWh, £1:36, removing the standing charge this works out at 22p per unit, should be 8.95p per unit, looked at solar software it shows used 5.1 kWh but that's still 15p per unit, so looked at the app last date 18th April and compared with Solar software 10.02 kWh and 10.2 kWh so it seems nothing wrong with the meter, solar and meter showing about the same, it is the IHD which seems wildly inaccurate.

OK I have the solar display so don't really need to IHD, other than to show £. I glance at it. Green means export, and multi-colour means import, never really looked at the watts, the problem is there is a delay with solar software, maybe 5 minutes only, but can't as a result compare solar to IHD as to watts import or export. Could use clamp on, but not really that worried.

Yesterday was about the second day where I have only imported all at low rate of 8.95p a kWh, this morning also good weather

the battery has lasted until the sun has come out, so likely another day with all import at 8.95p per kWh, but using the IHD is not showing a true reading, seems may as well unplug and save a little energy. But is it just mine, or are most wildly inaccurate?

 

[flameport]

IHDs and their implementation are junk.

Best to switch it off and never use it again for anything.

 

[JohnW2]

So waited until 3 minutes past midnight and looked at the readings on the IHD, 5.1 kWh, £0:00, of which of which 59.3p is standing charge is included. Clearly that is wrong. Waited a bit longer around 25 minutes into new day, and no charge. At 0:30 the battery starts to charge. .... In morning looked again 3.49 kWh, £1:36, removing the standing charge this works out at 22p per unit, should be 8.95p per unit, looked at solar software it shows used 5.1 kWh but that's still 15p per unit, so looked at the app last date 18th April and compared with Solar software 10.02 kWh and 10.2 kWh so it seems nothing wrong with the meter, solar and meter showing about the same, it is the IHD which seems wildly inaccurate.

I take it that your battery charging is only occurring during the 5 hours of very cheap electricity? If there were any charging outside of the very-cheap window, the overall ('average') would obviously be appreciably above 8.95p per kWh.

There is a smart meter (and IHD) in one house I'm involved with (which has straightforward single-rate tariff and no solar etc.) and the IHD seems totally accurate in comparison with other means of measurement, both in terms of energy usage and (once I had realised it was adding on the standing charge!) cost. I wonder if yours doesn't fully understand the tariff you have - and I also wonder what it does if/when you are exporting?

 

[Mister Banks]

My IHD was accurate when I was on the standard variable rate tariff but now that i am on the Octopus tracker tariff it shows correct info for energy usage but is wrong on the cost. Octopus did warn me that this would be the case so I now just use the phone app which is accurate on both counts.

 

[JohnW2]

My IHD was accurate when I was on the standard variable rate tariff but now that i am on the Octopus tracker tariff it shows correct info for energy usage but is wrong on the cost. Octopus did warn me that this would be the case so I now just use the phone app which is accurate on both counts.

As I said, the one I know of certainly displays correct cost with a standard variable tariff - and I sort of implied in what I wrote, that what you suggest sounds like a credible (albeit unsatisfactory) explanation for what eric is experiencing.

However, it seems a little odd, in that the IHD obviously does get some pricing information from the meter in order to work out costs at all. It would presumably 'notice' (and behave appropriately) if the meter told it that the SVT price had changed, so one might expect that it would also be told about (and behave appropriately) time-related dynamic changes in cost with a more complicated tariff.

 

[ericmark]

Had the IHD showed correct price for old tariff, or new tariff at just one rate, I could understand it. However it has got what I use wrong, the cost of what I use wrong, I did wonder if simply missed standing charge, but no calculation seems to show anywhere near what actually is the correct figure.

As said the app seems OK, although it gives no prices, but the IHD is so wildly out to be useless. And yes set to charge battery at cheap rate, so that 5 hours is enough this time of year to mean £1.06p today for all my electric so far, not £1.36 OK 30p not much, but what is the point of all those adverts when the display is so far out.

And I am sure most want to know cost, having "no data available for this time period" seems to defeat the whole point in having a smart meter.