Home Load Showing Zero

Hi All,

Apologies if this has been answered at some point already. Had the GivEnergy 5kW inverter installed on Monday. I've noticed at times of low energy usage, the house load will show as 0W. Is this normal?

The attached image, shows a 0W load at a time when the house would be "idle" but still have 2 x fridges, monitors or tv's in standby, Google Home devices, and alarm etc...
How sensitive should the CT clamp be?

I should note, that it does show load at other times when devices are running in the house:
Below is two time periods snipped from the data.. 3pm showing 0 load. 11am showing load

Much appreciated,
Derek

Derek214 Looks like you're generating 5kW, and presumably exporting virtually all of it, since the battery is full. Does it happen when you're not generating so much ?

Yes, I see this from time to time, though using the free android app rather than the standard one. https://givenergymonitor.wixsite.com/tutorials (In fact, I think I've even see it go negative.)

I think the problem is that the house load is inferred, rather than being measured. The only thing the inverter measures is the grid import/export, through the CT clamp. It has to infer the house load based on the difference between the grid measurement and how much AC power it's producing. When measuring two numbers of the order of 5kW each, it's not surprising that the difference could have a large error.

Derek214

No, your figures are not normal. The house load is calculated as the inverter output minus the grid export.

Your energy meter is significantly over-reading. At 11:52 it registered up to 5890W being exported which simply isn't possible with a 5kW inverter. It is normal for the CT clamp reading to be 1% or even 2% out, but not nearly 20%. Badly fitted CT clamps usually under-read, not over-read. Is the CT clamp attached to a cable that is looped or coiled in some way?

DD I think the problem is that the house load is inferred, rather than being measured.

Exactly right. In this case there seems to be measurement inaccuracy too.

I have been looking into this again recently. I developed my app in winter (on Octopus Go) and noticed my EM115 meter was under-reading when charging the battery. The inverter would be consuming 2600W but the import would only read say 2580W, so logically the house consumption was -20W. To fix this there is a CT correction setting.

However now it is summer, I have noticed my EM115 over-reading when exporting, so inverter outputting 3600W but export reading 3620W so again logically house consumption is -20W. The correction that worked in winter now makes this error worse.

Not sure why my EM115 under reads when importing but over reads when exporting. May be connected with the voltage generally being higher when exporting.

Rubikcube is it related to the location of the EM115 meter in relation to the inverter given its uses voltage to calculate - I.e the EM115 may or may not be located a short distance from the inverter such that volt drop across the CU is just enough to mess the readings up?