Battery discharging to 10% in an hour

[Maz]

Hi, we recently had a 5kwhbattery installed to go with our existing solar panels. There were a lot of problems but finally got the system working. I charge the battery to 100% between 2 and 5 am when our tariff is cheapest, but the battery discharges between approx 5 and 6 am when we are not using anything. I have checked our heating and hot water which runs fine. We often wake up to having used £6 of electricity and empty battery, but then only use about £1-£2 for the rest of the day when we are using various appliances. Can anyone please suggest a solution as I have tried everything I can think of! Thanks in advance

[Dave Foster]

You’ve not said which system it is, is it a solar inverter with an add on AC battery, or is it a hybrid with solar and (now) batteries?.

I really need to see your energy flow screen from either the app or website, but it sounds very much like the CT clamp has been placed in the wrong orientation - when it is the wrong way round it will dump the battery immediately to export when it stops charging.
The CT clamp is a current transducer that clips to your live cable from the smart meter and measures the house load, the inverter needs this to know how much power it needs to generate for the house when running off batteries. You will usually find it clipped to the live cable where it exits your smart meter - a photo of your meter cupboard would be useful.

But just to double check, you don’t have an EV that is charging at the same time that would flatten the battery, or some large appliance that is taking power around 5-6am - any graphs / images from your app or the website that show the load vs the battery charge / discharge would be helpful.

[Maz]

Hi Dave thanks for coming back so quickly. I know very little about the system. We already had solar panels on a new build house, then the battery was added and the inverter upgraded to fit with the battery. I have attached a pic of this morning.

[Maz]

Also, we don’t have an ev charging and no large appliances. Heating/ hot water on air source heat pump running 24/7 but nothing kicks in early morning that I can find

[Dave Foster]

Yes that looks very much like the CT clamp is pointing in the wrong direction - you have 2 options, call the installer and ask them to rectify it, or you could locate and turn the clamp around yourself, it's not too difficult,

If you post a photo of your meter cupboard i'll confirm where it is - the CT clamp has a clip on one side that can be opened it will then spilt open and you can turn it through 180 degrees (you'll see there is an arrow on the clamp to help you with orientation).

They look like this -

IMG_1656.JPG (9.86 KiB) Viewed 1145 times

IMG_1655.JPG (9.69 KiB) Viewed 1145 times

[Maz]

Thanks Dave, I will ring the installer on Monday to check it as I am not very technically minded! I will come back and let you know either way

[Maz]

Have just checked the smart meter and can’t see anything that looks like the Ct clamp shown?

[Maz]

[Dave Foster]

Ahh ok, it's a 3 phase house - basically the same principle but you have 3 CT clamps that measure the load on each phase.

It could be one CT clamp, 2 or all 3 that are the wrong way round, so yes best to call your installer and they can test each phase to make sure it is reading correct.

Once the CT clamps are the correct way around as long as the batteries have enough charge they should only discharge to meet the house load, and any excess solar should be used to charge them.

[Maz]

Thanks Dave - I will get onto it on Monday

[Maz]

Ok so I have been doing some more digging since yesterday and come up with a sort of solution till tomorrow. The set up I had when the battery was discharging itself is in the third pic, and then I tried a different set up last night where the battery did not discharge itself and still had plenty of charge this morning. 1st and 2nd pics

Is there anything wrong with the settings on the mode scheduler or do you still think it is probably the CT clamp?

[Dave Foster]

You’ve set it to charge the battery between 3 & 5am, and then not to use the battery at all from 5 til 7 which will stop it discharging - but the big question remains why was the battery discharging after 5am when there is no house load, that is usually a sign of reversed CT clamp if there was no load present.

Can you post a shot of your energy flow (the overview page that shows the house) and also on that page if you swipe left and post the graph at the bottom of that page (as it shows house load).

[Maz]

Hi Dave, these have just been taken

[Dave Foster]

On that first image, when you swipe left can you scroll up the page and you should find a graph at the bottom of the page that looks like this -

That will be really useful to see as it shows your house load, solar, grid use and battery together

[Maz]

Here it is

[Dave Foster]

I can’t see much wrong with that trace, the load appears to be showing correctly which it wouldn’t if the CT’s were the wrong way round and the battery is taking charge when there is spare solar and you are exporting (a little) as well.
It is possible that one CT phase is wrong but i’m not seeing evidence there.

I would be inclined to let it run like this and see how the system performs over the next few days.

[Maz]

Thanks Dave,
Should i run the mode scheduler rather than the way I have it now as at least I have full battery in the morning at the moment when i didn't when running the mode scheduler? Can you see anything that is taking a big load early morning?

[Dave Foster]

No I think it’s best to leave it the way it is, the charge periods can only charge or hold the discharge, whereas the mode scheduler can really change the behaviour as well as force the batteries to discharge.

There’s no obvious load at 5am so hopefully a few days of running like this will give you some confidence in the system.

[Maz]

Thanks Dave I really appreciate your help with this. I will ask installer to check the CT clamps and run it like I have at the moment. Will post again if I get any significant updates