How much juice does a CIU pull?

[Flanders]

Greetings power propeller heads,

I'm trying to figure out why my sunsynk data differs slightly from my meter reading. I've tested now on two separate days from midnight to midnight and on one day, meter read 1.4 kWh higher than sunsynk's import stats for the day. The other was 0.9 kWh higher than sunsynk's measurement.

CIU sits "in front" of the inverter and so there's an expected discrepancy; but these figures, although fairly negligible, are higher than I was expecting.

What could be the reasons for there being a difference between the two measurements?

 

[Lupus]

Barely anything, do you have anything that isn't connected to the Sunsky? A geyser? Stove? Could it be the 20w sunsky need to keep alive?

 

[PaulGherkin]

The CIU is supposed to use less than 1 watt
Also, please mask out your CIU number from that photo...

 

[Flanders]

Barely anything, do you have anything that isn't connected to the Sunsky? A geyser? Stove? Could it be the 20w sunsky need to keep alive?

I'm leaning more towards it being something like this. It's the 12KW sunsynk and I'd calculated that it runs on ~160W on average per day - this was based on the app's stats alone and didn't account for losses ((import + PV) - load) so is likely less than that. I wasn't aware of what it required to keep on ticking.

 

[Flanders]

The CIU is supposed to use less than 1 watt
Also, please mask out your CIU number from that photo...

So definitely less than the ~60W being used on the 1.4kWh day.

PS. - that's a pic from google, not mine.

 

[PaulGherkin]

Also note that the prepaid meter is certified to a specified (IEC/SANS) measurement accuracy. I doubt the inverter has been certified to that (it is not required to) so measurement error might likely be higher on the inverter.

 

[Tomtomtom]

Greetings power propeller heads,

I'm trying to figure out why my sunsynk data differs slightly from my meter reading. I've tested now on two separate days from midnight to midnight and on one day, meter read 1.4 kWh higher than sunsynk's import stats for the day. The other was 0.9 kWh higher than sunsynk's measurement.

What's the relative error (difference in readings as % of import/total energy) and is this stable?

 

[Flanders]

What's the relative error (difference in readings as % of import/total energy) and is this stable?

I'd probably need to test over 5 days or so to see if there's a pattern but no, doesn't seem to correlate as % of import. Both import figures were very close (within 1-2kWh IIRC).

 

[Tomtomtom]

I'd probably need to test over 5 days or so to see if there's a pattern but no, doesn't seem to correlate as % of import. Both import figures were very close (within 1-2kWh IIRC).

If it's a relatively stable difference regardless of total import then it supports the idea of there being a real load e.g. the inverter itself, rather than (only) measurement error.

 

[leon.davibe]

was the CT coil wire lentgh extended ?

 

[Flanders]

was the CT coil wire lentgh extended ?

That's just pure greek to me unfortunately.

 

[PaulGherkin]

That's just pure greek to me unfortunately.

Yes, to many others too

 

[leon.davibe]

That's just pure greek to me unfortunately.

same here
just remeber seeing this a while ago and that it may affect the accuracy of import /export data