I am looking for advice for a small grid tied battery.

[ArieKanarie]

I have a few 100AH CALB LiFePo4 cells laying around with ~90% SOH left.
Because I have 16 pieces at this moment (they come from my electric car and I could extract more), I was planning to make a 8S2P battery to use 24V equipment.
Because the cells in my car are due to be replaced I am planning on just making 8S modules in a rack everytime I collect 8 of them and then connecting them in parallel.

But now the part where I'd like to get some advice:
Which inverter Is suitable for my usecase?
I'd like to charge with a maximum of 500-750W (variable would be great)
I'd like to discharge with max. 1000-1500w
The ability to somehow control/monitor with homeassistant is a must
To be able to zero my electricity use would be great aswell (how would that work? current meter?)

Thank you in advance.

 

[50ShadesOfDirt]

If you haven't done so already, consider some up front design effort ...

The design steps:

1. Go here, and enter in each appliance's values (watts, hours/day you want to run it, etc.):
unboundsolar.com/solar-information/offgrid-calculator

2. Go here, using numbers from above, and fiddle with various entries/components, and you'll see in real-time what your system component (inverter, mppt, panel) sizing is:
altestore.com/store/calculators/off_grid_calculator

There are many similar website pages/calculators, but these two pages should help you get through most of the necessary calculations. This helps you quickly decide if you can do what you want to do, and you can vary component choices for what-if scenarios.

I'll go out on a limb and assume that you want some loads hanging off an "off-grid" solution, which just happens to get it's power not from solar panels, but from a grid connection (aka "shore power", which you'll feed into the AIO). If assumptions right, then a small, standalone system would likely consist of an All-inOne (AIO) inverter, a battery-bank (what you'll be building out of LiFePO4 cells, bms's, & such), solar panels (which you are skipping at this time, but might add in later), along with connecting bit & bobs (cables, fuses, etc.).

Tons of resources on this forum on all the methods for building a battery from cells; ditto on monitoring (usually a function of the BMS you choose); just use the "search" function to find them all. I'd look at SOK batteries (currentconnected.com) as a standard for comparison while building your own. Fully serviceable, field-replaceable components, etc.

Hope this helps ...

 

[ArieKanarie]

Thanks for the input.
Just to clarify: I am not trying to go completely off-grid.
I am just planning to store some excess solar power during the day to use in the evening, while re-using the replaced cells because they still have some life lef tin them.
I don't want to replace the current solar inverters that I have because of their locations.
My outdoor shed will be used for the batteries because of fire safety.
I am aware to never charge lifepo4 below freezing, I'm thinking to make an insulated battery box with small heaters to keep it just above freezing.