Increased power consumption following Solar PV installation

QrizB

That's making more sense now.

Inverter internal stats are always wrong. They vary by how wrong, but they're not calibrated and not certified and are best treated as "for indication only".

Your numbers look to be unusually wrong, though. It's possible that your installer configured something incorrectly; told the inverter he'd used less sensitive current transformers, for example.

Does your software give you a live readout of this "house load" parameter? If you add a large load (eg. switch on the kettle) does the house load increase by a value appropriately equal to the value of the load, or does it increase by a different amount?

itm2

https://forums.moneysavingexpert.com/discussion/comment/82051039#Comment_82051039

Maybe slightly different, but in this case the difference is close to 100% in some instances

HalfFull

https://forums.moneysavingexpert.com/discussion/comment/82051047#Comment_82051047

But only a couple of percent of the maximum load those sensors might be able to read. Also at the low-ish loads you have in your table the power factor is often far from unity, as we all have many low level .capacitive loads these days. This makes it more tricky and needs an consistant methodology to come to the same answer of real power.

Heedtheadvice

Some great responses there for what seems a contradiction of results and illogical increase in house load.

Now you explain the different measurement sources it is obviously like comparing apples with oranges so it would be good to get measurements of the same load at the same time. Similar to Squirrels suggestion.

Are you able to isolate the battery and isolate the solar panels at the same time whilst power to the inverter is retained? ( it should normally be possible). You could then compare like with like: the info provided via Octopus and that from the inverter measurement both of total house load. This could be done at a convenient time or two with a low load time ( say 8 am to 9 am looks good from the data you provide) and also in a period with a high house load ( such as by following up the low use 30 minute period with a period boiling a kettle full of water several times.

Within the limits of measurement accuracy ( high accuracy from Octopus, to better than 5% from the inverter) they should be the same. As you will not be generating from the solar or batteries they will be measuring the same load ( including any power consumed by the inverter).

If there is a difference then the inverter measurement is suspect, more diagnosis to find out why.

I they are the same energy readings then it would seem your house load has actually increased. Repeat with all house loads switched off ( that will leave the inverter standby the only power draw ), and then house loads on and your constant running devices ( fridge freezer etc) loads off for just a 30 minute period) that will show if there is another house device load.

itm2

https://forums.moneysavingexpert.com/discussion/comment/82051043#Comment_82051043

I have a smart plug which measures energy consumption. So I plugged a 1200W hair dryer into it, It reported a power draw of 1,292W.

I then checked the power draw figure reported from the inverter. It had increased by 1,350W.

So the inverter seems to be reporting incremental increases in load reasonably accurately.

Reed_Richards

Your electricity meter measures the energy you consume but your inverter takes periodic measurements of the current from which it derives a power reading. I have one device in my house that switches on and off frequently. This can get in or out of sync with my inverter readings in which case the inverter either sees it as full-on or completely off. So the inverter gets the energy consumption data wrong.

itm2

https://forums.moneysavingexpert.com/discussion/comment/82051109#Comment_82051109

If I observe the load figure being reported from the inverter it seems to update every 15 seconds or so. In general the readings I am getting from it do not vary wildly from one period to the next, provided no major appliances are turned on/off in that period. So the data in the table posted above (from the inverter) are probably a close enough approximation of the power consumption for a given period.

How this compares with Octopus's method of measuring usage I have no idea (which was the basis of the May data in the table)

Netexporter

Has the battery got heating? I know the earlier Fox batteries didn't, so suffered in cold weather. If yours does having heating, could it be permanently on, for some reason? (I believe they draw the heater current from the mains, not the battery itself)

Qyburn

Regarding measurement sources and just for reference, our Solaredge system over estimates solar production (compared to the generation meter), and underestimates import/export (compared to smart meter). Taken together those result in the calculated "house load" being overestimated by a variable amount.

Even if solar is always 5% out, and import/export also 5% out, the effect on house load isn't a fixed percentage error.

QrizB

^ Yes, if the OPs inverter is measuring three parameters - solar generation, charge to battery and export - and using those to calculate house load, there's scope for several small errors to stack.

OP how is your system wired? Is house load measured directly, or is it calculated from adding and subtracting other values?