Ampy 5235a Electricity Meter

[JohnD]

electric bill

Changes in an electricity bill are not the same as changes in metered consumption.
Often there is a regular direct debit, which is calculated using past under- or over-payments, meter readings that may not be accurate, and estimates of future consumption, with a dash of an attempt by the supplier to get you to make interest-free loans to them by paying in advance for more than you will use.

Do you have records of the metered consumption per month, to compare?

 

[JohnW2]

We dont have economy 7 though we have toyed with the idea. We work part-time from home. So it might end up costing a lot more for our daytime activity.

Fair enough, and thanks for the clarification. With most suppliers, you have to use more than around 33%-35% at cheap rate in order for E7 vto be financially advantageous/desirable.

The Powerwall was intended to charge from pv and discharge for our general consumption including EV charging. Obviously not much in the winter months. It is also showing unexpected signs of poor efficiency ie about 20% loss between charge and discharge.

Given that the generation figures you have reported for Nov-Jan (which I imagine represent a fairly small fraction of your total usage), the thing I find a little difficult to understand is how you would ever have managed to export anything, even without the Powerwall. Over than 3-month period, your generation averaged about 1.2 kWh/day**, and if one assumes that relates yo just 8 hours generation per day, that would correspond to an average load of only about 150W during that period - which sounds very low, particularly since you are working partially from home. I would therefore have expected that all youir generation would have been used by you in real-time, leaving none to be exported, even if you had not had the Powerwall installed.

[ ** to put that into perspective, a 7-minute shower with a 10.5 kW shower would use more than that, as probably would boiling a kettle half a dozen or so times! ]

Kind Regards, John