Battery Health - Charge from Grid?

Hi, I've had my Solar PV for 10 years but just this week had the All in One and Gateway installed.

Thinking about battery charge levels through periods of several days with poor solar production and then the winter months where there will be likely little or no spare solar to go into the battery.
If I leave it in Solar charging only, the battery will probably only get to, say, 20-30% max or just stay close to the reserve value in winter.
For Winter I was thinking of setting to Solar + Grid charge, say to 70% max charge for a period of the day, which would give more reserve in the event of a power cut, but would this also be beneficial to the health of the batteries over having it sit for a couple of months near to empty?

Currently on a flat rate tariff so makes no real difference (ignoring efficiency factors) whether I charge the battery then use from battery overnight or draw direct from the grid when required.

Thoughts?

With the type of battery, don't believe there's any issues with leaving it at a certain percentage. Unlike laptop batteries etc where it's best to leave them at 50%.

There can be issues where the system thinks there's more left in the battery than there is, so perhaps an occasional fill to 100% would be a good idea. Unless you get a very sunny day say once a month anyway - fingers crossed on that!

But otherwise with the conversion losses AC to DC to AC again, it's not worth charging from mains on a tariff that doesn't offer off peak rates.

TX200

Yeah the more I read up the more I’m inclined to just leave it in auto and do an occasional full charge.
Also reviewing tariffs and doing sone calculations for when my current deal finishes to see if I can get something with an off peak rate.

treborUK

I’m not sure what your (winter) daily kW usage is or what your fixed rate is or if you have a heat pump or an EV - but Octopus Energy have some good off peak tariffs.
Intelligent Octopus for example gives 6 hours at 7.5p and peak of about 30p ish. So, if you can use the majority of the stored off peak during the day instead of any peak that’s a big saving. Plus if you charge too much and have to export it, it’s only a 3.5p loss (7.5p import - 4p export!). And it’s only a loss if you don’t use it and it actually gets exported!

It’s entirely dependent on the above of course but filling the battery during off peak in winter (instead of/ supplementing from much less solar) and using it during the day for as long as it lasts seems to be the way to maximise savings.