EDDI exporting despite my SunAmp not being 'full'

[ToughButterCup]

I use Windy's Solar Radiation (Power) layer ( solar power and UV index) to help me predict how much to boost our water heating once the sun has gone down. So I'm almost always well aware of how much 'water heating ' I can get out of the sun on any one day. Yes, I know, its not for everyone. Most will just want the system to tell you how much hot water you have left .

 

But. 

 

 I know for sure (at least I thought I knew until the stats below became available) that this month, we never generated enough solar power to fill our SunAmp  - trees in the way and lack of sunshine.

 

And then I saw this: I'm actually EXPORTING to the grid ...  not much, but I am. And that tiddly bit of power is worth more to me as heated water than exported

From Octopus I get this

 

and checking on my EDDI I get this

 

 

The only thing I know for certain is that power is being exported to the grid when it could have gone to heat our water.

(The EDDI will not give me a readout for last week's export value)

 

Am I doing anything wrong? Could I change any settings to prevent small amounts (20p worth) going to the grid ?

 

Edited October 30, 2023 by ToughButterCup
hyperlink added

[JohnMo]

Is there a threshold (W) where the Eddi starts heating water, mine not an Eddi, doesn't make hot water until the export is over 100W.

[SteamyTea]

I suspect a threshold and parasitic loads.

[sharpener]

If the Eddi is like the Zappi (also from myenergi) then you will be able to change the grid balance point in the direction of exporting less. But you might find you then start to import when you don't want to, it will never be perfect.

 

My solar diverter is home-built but like @JohnMo's takes 100W export to turn it fully on. So you might not have much scope to reduce it further. It is something I was prepared to live with rather than spend time experimenting with the control loop, it has worked well for >10 yrs now.