Hybrid grid tie inverter options / suggestions

Hi I am in the very initial stages of planning an installation

I’d like some advice on a suitable inverter product for my house, I want to install an inverter to act as a supplemental power to the mains grid, utilising LiFEPO4 cells

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the intention is to charge ~10Kw between the hours of 2-6a.m. (cheap electricity) and then consume that during the day through a ~5Kw inverter.
Key requirements are :

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1) seamless transition between battery power and Grid supply (i.e. no brown outs etc)

2) ability to work initially without solar panels (solar install planned for next year)

3) If the power draw is greater than the inverters ability to supply it would pull the remainder from the grid i.e. a 10Kw shower unit

4) ability to charge the batteries from the grid

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Hope you can point me in the right direction

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P.s. fwiw its a 230v supply single phase Uk based

Thanks