FoxESS Community - Owners & Installers Forum

Had my system installed a little of 3 weeks ago!

16 x 435W Perlight Panels (6.96 kWp)
6 kW H1 Inverter
12 kWh Energy Cubes

Also had a SolaX EV charger fitted that the installer fitted for free!

Just getting used to everything. But I have integrated the HA Modbus Integration, along with the charger and just playing about with all the settings to optimise for our usage. Now the weather has turned I need to automate charging the batteries for Octopus Go over night.

I also want to monitor the temperature of the batteries. I was a little worried about the temperature fluctuations since its installed in the loft. But will monitor and come up with solutions are the need arises.

One thing I did wonder though. When running on battery theres quite often a small draw from the grid, like 10-30W. I just assume this is just the margin of error from the CT clamp and/or the inverter not detecting the small amount?

Hi, welcome to the forum and the beginning of your solar journey

In the loft temperature may be a problem in the very cold spells where you have several days below zero - typically the batteries restrict the charge current as they get cold, and it's all over below zero - although they will continue to discharge.

What many people have done where it is a problem, is to build a Kingspan (recticell etc..) battery enclosure with 50mm insulation boards leaving an airgap around them for air to circulate - looking at your install it should be quite straight forward.

The inverter doesn't use any grid power to stay awake (what little it takes from grid is bias current to stay synchronised), the small draw you are seeing coming from the batteries is essentially the power needed to run the inverter, BMS and batteries and any losses when there is no solar to fall back onto.

Thanks for the confirmation on the small draw, makes sense!

I'll monitor the temperatures and see how things go. I already have some zigbee thermometers up there to measure the ambient temperature. As you say should be easy enough to insulate with a small enclosure! I've already seen the charge being throttled when it was cold but very sunny.

Already seeing battery charge being throttled due to temperature of the batteries. Was quite cold last night. Ambient temperature in the loft was 3oC and the battery is only charging at 1.1kW, with a temperature of 15oC.

Think I'm going to pop down to B&Q this weekend and see what I can cobble together! I've seen a few example now on the facebook group, should be easy enough, even with my limited DIY skillset!

Built a small enclosure as recommended. Already noticing the battery temperature is more stable this morning after another cold night.

Temperature inside the enclosure is currently about 9oC more than the ambient loft temperature! Battery has stayed above 20 all night too!

Nice that should do the trick.... the world would be lost without duct tape

Nice neat install and love the insulated box to keep them at a stable temp.

Thanks both!

The temperatures have been more stable since I built the box. But the weather has also improved, so time will tell.

I have noticed that the battery temperature reported by the fox cloud app (lower) is different to the one reported by modbus. I don't suppose either of you know what the difference is?

The app reports the lowest cell voltage, whereas modbus is reporting the BMS temperature which will be 5-10C higher.

The H1 (Gen 2) & KH inverters don’t currently report the BMS low and high cell temps, but this might arrive in a future release as Fox are changing the modbus registers to align to their new specification.

Makes sense, thanks

adamlc wrote: ↑Sun Oct 13, 2024 11:58 am Built a small enclosure as recommended. Already noticing the battery temperature is more stable this morning after another cold night.

Temperature inside the enclosure is currently about 9oC more than the ambient loft temperature! Battery has stayed above 20 all night too!

I'm going to copy this How much space did you leave around the battery for airflow?