FoxESS Community - Owners & Installers Forum

Hi all, We had our 2 x 10kw batteries installed yesterday and are just looking for some assistance to make the most of overnight Octopus Go 8.5p Kw rate.

We have been on Octopus Go for a while and overnight we usually heat our swim spa for a few hours depending on how much the temperature has dropped in the day (it is on an automatic controller between 00:30 and 05:30).

Now we have the batteries we hope to charge them up during the same time slot and I set this up last night and it worked well.

I have been reading about the battery health and wanted to check something. Do the batteries draw from the grid and the house/spa draw from the batteries or does the spa take direct from the grid?

Kind regards

A

AJH wrote: Fri Feb 28, 2025 6:03 pm Now we have the batteries we hope to charge them up during the same time slot and I set this up last night and it worked well.

I have been reading about the battery health and wanted to check something. Do the batteries draw from the grid and the house/spa draw from the batteries or does the spa take direct from the grid?

Kind regards

A

Hi, welcome to the world of solar.

If you have a large load such as an EV or a spa and are running it on a low tariff you want to make sure the batteries are set to charge at the same time (usually in the Go period of 12:30 to 05:30) to avoid them discharging into the house (spa) or EV.

In Self-Use (the default work mode) any solar will firstly cover the house loads (including the spa) and if not sufficient the batteries will make up the difference to the maximum inverters output. i.e. if you have a 5kW inverter the maximum it can provide from solar and batteries is 5kW and anything over that will come from the grid. If your spa had (say) a 7kW heater then the inverter would provide 5kW (from solar/batteries) the remaining 2kW would come from the grid.
At night when there is no solar the batteries (assuming they have charge) will provide power to the house including the spa.

Great - that makes sense. thank you so much - it is only day two so still digesting all the information.
A