FoxESS Community - Owners & Installers Forum

Hi all,

Ive had a system installed yesterday so I'm still very much a novice when it comes to solar and how to use the app etc.

System is Fox KH7 inverter (7kwh), 1x EP12 battery (11.52kwh), 20x 500w panels but with 8 facing roughly south and 12 facing roughly north. I know the north facing panels will only produce half that of the south facing panels and are virtually useless in the winter but we wanted a system capable of matching our annual usage.

There are 3 things i want to know so some advice would be great.

My battery had 45% when installed and this rose to 70% yesterday due to it being sunny, and was then exhausted (10%) by around 11pm. Today because it was overcast, it only got to 50%.

Taking into account we are just about to hit December and i don't anticipate much PV production. I'm wanting to fully charge the battery so i can see how long it lasts, how fast it charges from the grid etc, so i have an idea of how to use the system best.

1) Will the battery charge from the grid automatically or do i need to set a forced charge schedule overnight? I'm still on a standard eco7 tariff so my off peak period runs 23:30-06:30. The tariff will get changed once i have figured out the best tariff and have my certificates etc.

2) If i set a forced charge schedule overnight, what happens when the battery is full. Will the schedule end and the battery will supply the house, or will it just sit there doing nothing until the schedule finishes? Based on the assumption it will do nothing until the schedule ends, how long will it take to charge from 10% to 100% roughly so i can set a tentative schedule? I know that temperature will have an impact so this is not a straightforward answer.

3) Last night the battery dropped to 2 degrees so Ive set the warming function to start at 7 degrees and heat to 12 degrees. If the battery is heating, will it still charge from the grid if forced charge is set, or will charging not occur until the warming mode ceases? If it is charging from the grid, will the charging process create heat and therefore the warming function not be required or will the charging rate be throttled to much due to low temps to generate heat.

1) You'll need to setup a force charge window

2) the battery will hold the fullish level until the charge window is over, it will not flip back to self use just because the battery is full

3) I would run the battery warmer even when force charging just to ensure optimum battery temps during this cold snap

Thanks Will,

You've confirmed what i thought.

Do you know if the battery will still charge from the grid while also warming from the grid, or is it one then the other.

I ask because last night looking at the chart below, it would charge for an hour equating to 15% battery, then stop for about 90mins, then charge for another hour. I can only assume it stopped charging because the batteries got too cold, and then continued once the warming target had been met? Will it also charge if on warming standby? Ive seen someone mention that it wont but i dont see how this could be a thing.

3hrs charging (7hr time period) for 45% capacity is disappointing but it was only charging at 2.5kwh. Due to temp throttling i guess?

From experience with my system from grid the battery will either charge or heat. "Warming standby" is just that - warming is enabled but not active due to cell temp being above the trigger point, the battery should charge in this state.
If charging at the full rate the inverter is capable of your battery should charge from 10 to 100% in 1.5-2 hours if the cell temp is above 11°C at start of charge - the cells will heat further due to the charging process.