HI guys,

Our Estate's third party electricity supplier let's us export to the grid. We get a 1 on 1 Kwh return (Nice!).

My Bi-directional meter was  installed on 5 July and I have monitored the readings on a daily basis, with great enthusiasm. 

There is a huge difference between what my Sunsynk inverter says what I have exported and what the Bi-directional Meter says.

Has anyone experienced this?

I have queried my Supplier about this but I am still waiting for an answer from them. 

My import/export data since installation:

Import always close until last month. Not sure why, waiting for the next account. Export always a difference. It's more than what Sunsynk data says, so no complaints from me.

 

I use GridBuy and GridSell data fields.

 

Edited July 20, 20232 yr by ZaydS

Hi, @BernardT Were you able to get an answer regarding the difference between the exported power showing on the Bi-directional meter vs Inverter?

Hi Fahim, apparently your Bi-directional meter is much more accurate than the Sunsync inverter.

As I understand it the inverter records only every 5 minutes, while the city council meters every second. (That's why they're so expensive).

I have noticed this myself. When I boil the kettle for coffee every morning, (it takes about 3 minutes) my graf sometimes doesn't even show a spike  like the pic attached.

1 hour ago, BernardT said:

As I understand it the inverter records only every 5 minutes

That's not quite accurate, if you are talking about data recorded on Sunsynk's data site with your Sunsynk WiFi dongle, then yes, but data is accumulated in 5 minute segments then, so it should still be accurate, but won't show short term spikes of power nicely, but they will be counted...

If you ran Home Assistant with @kellerza's Sunsynk/Deye Inverter Add-on locally, then you could record some data on a 1 second basis and would see some of the energy spikes more clearly... see a history data graph for yesterday 00:00 until today 14:00

You can see earlier today the Inverter power spiking to near 5kW and just over 5kW, when I was mowing the lawn earlier (old Wolf 2000 electric mower). see the next one, where the time slot is from today 10:00 to 14:00, but since its only 13:12 now, it obviously doesn't show beyond current time (can't predict the graph into the future :-))

 

Indeed, the inverter measures power frequently. These are used to update energy/kWh measurements (it has to be measured whenever the power changes!). So if you run a local solution like the addon, you can see changes per-second for immediate power usage.

It's good to know that Sunsynk is typically measuring extra energy usage for export - since most people in SA gets penalised for this!

I doubt measuring every second is enough, there are too many factors changing on a sub-second basis (the load, panel shading, mptt tracker, sampling rate on the CT sensor, maybe even some effect of hysteresis in the CT coil, slight voltage changes on the grid, speed at which these voltages changes are measured and factored into the measurement).

If you know more about the external meter & inverter internals you could probably come up with a bigger list.