FoxESS Community - Owners & Installers Forum

I've got my FoxESS Inverter (with solar + battery) feeding into Home Assistant via a ModBus adapter which is working fine. I'm running on Eon Next Drive tariff which gives me 12-7am cheap rate. Over the summer i've been generating plenty of excess solar during the day and the battery has been sufficient to cover overnight. As a result I've had the system set on a schedule (configured through the FoxESS app directly) to do 'Feed In Priority' during day to sell excess solar and then charge the battery overnight for cheap. So far so good.

However, now winter is approaching, I'm finding I'm using battery more during the day and run out of battery before midnight. Based on this I figure I need to switch to 'Self Use' mode so that on a regular day, any extra solar tops the battery back up first as no point selling it only to have to pay more to buy it back again later in the day.

This lead me to start looking round at Home Assistant based 'smarter' options. I've looked at FoxESS Energy Monitor integration - but from what I can see that just manages how much charge to put into the battery for the next day's usage - and as my usage is quite high we'll always end up using 100% of the battery so this doesn't help me? I assume what I really need here is to setup PredBat which offers more strategy? Can anyone share how they approach this?

Hi Mark,

If you'll always use 100% of the battery then it might be your capacity is undersized, or you need to rethink your strategy and consider it more of a cost-mitigation exercise to see how much usage you can shift to your cheap rate. You won't get much solar during winter - last year my worst month was December with 70kWh of solar (vs 951kWh in June).

The simple approach which will get you most of the way with least fiddling will be to move all your big loads like washing to overnight, charge up overnight and use the battery to coast through the day.

If you want something to micro-manage the charging for you then both the options you've mentioned will do a good job. I used EM when I was on a fixed-cost-fixed-timeslot tariff like yours and it was good. I moved to Agile with the half-hourly rate changes I found it wasn't suitable, and I've recently started with predbat.

Predbat is doing OK for me - have had the occasional hiccup as Fox inverters aren't fully supported/tested as far as I can see. Have had instances where it's not started charging when it should, but that could be my configuration. The add-on was easy to install, but the config setup does require some reading to understand the settings.