FoxESS Community - Owners & Installers Forum

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

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.

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.

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

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 -

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

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

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.

Thanks Dave - I will get onto it on Monday