Why is my battery power getting sent back to the grid (as well as powering the house)

[risky_boy]

Hey all. I’ve just discovered this forum and there are some brilliant people and solutions on here, so I’m hoping someone can help me… my solar installer was useless and didn’t really know what he was doing, so I’m learning all this as I try and figure out the system!

My first question/problem is “why is my battery power getting sent back to the grid, as well as powering the house” (I’d rather keep it all for the house)?

From the image below you can see (at least I think that’s what it’s showing) that 85W of power are being pulled from the battery by the inverter (there is no solar at nearly 10pm at night, so 0W from that), of which 64W are powering the house, but 63W are being sent to the grid?

If it helps, the bits that will probably be relevant to this question are:

• SolaX X3-Hybrid-G4 (10 kW) inverter
• 4 x SolaX batteries (1 x SolaX MC0600 HV10230 V2 (3.1kWh) and 3 x SolaX HV10230 V2 (3.1kWh) = total 12.4kWh
• 3-phase power to the house
• I have a MyEnergi Eddi also

Thank you!

 

[risky_boy]

I should probably add, the SolaX Inverter is in "Self-use" mode

 

[clydeps]

why is my battery power getting sent back to the grid, as well as powering the house

Check the inverter manual - you will probably find that 85W is within the margin of error for grid export (my inverter says 50-100W.) And there is probably a minimum load for the inverter to switch on (150W for my inverter.) 65W is an impressively low overnight load.

 

[radiomean]

Check the inverter manual - you will probably find that 85W is within the margin of error for grid export (my inverter says 50-100W.) And there is probably a minimum load for the inverter to switch on (150W for my inverter.) 65W is an impressively low overnight load.

Especially if the monitor(s) on the main meter lead is/are a CT(s) as opposed to a wired-in meter like an Eastron SDM230 (or SDM630 for three-phase). I was 'leaking' a continuous 50 to 100w with a CT, which has dropped to nearly zero with a meter... Only issue with a meter is that you have to break into the meter tails to install it...

 

[SeaGal]

The figures do not add up. If only 85W is being drawn from battery and you are sending 64W to the house and 65W to the grid you have an inverter that can solve the world energy crisis!

With no solar, I would expect about 30W of the 85W from battery would be used to power the inverter's electronics and the remaining 55W give you no more than 90% of that to the house taking into account the efficiency of inverter and power line losses - so maybe give you just 45W for the house?

What is strange is the figure of 127W shown by the inverter - what does that mean?

 

[clydeps]

What is strange is the figure of 127W shown by the inverter - what does that mean

It's the sum of the grid export and house load. One or both of those is probably inaccurate at such low loads - the grid export number especially, even more so if it's three phase. This is very much in the realm of fiddling at the margins - if my battery was showing only 85W discharge overnight I'd be cheering and moving onto other problems.

 

[radiomean]

It's the sum of the grid export and house load. One or both of those is probably inaccurate at such low loads - the grid export number especially, even more so if it's three phase. This is very much in the realm of fiddling at the margins - if my battery was showing only 85W discharge overnight I'd be cheering and moving onto other problems.

As I said I wonder if it's the CTs used, and if a meter like the SDM630 would help (the SDM230 for my single phase setup helped a lot...)

 

[risky_boy]

Thanks all. I'll give SolaX a call and see if there is a setting we can tweak/change to get this working optimally and will report back in case it helps other users.

 

[risky_boy]

Quick update on this. Very useful and helpful support call with Solax. In short, it apparently should be impossible for the battery to do this (send power back to the grid), so it might be a reporting issue from the inverter/app. The lady carried out a remote firmware upgrade on my inverter (apparently there was a small update) and has said to monitor the situation, and if it persists get back in touch and send them the screenshot from the app. Will monitor and see what happens now!