EV Battery As A Backup

[scotchonrocks]

I have a home-built EV, 5 years old with 35,000miles on it. 25kwh 162V battery. I'm currently looking at using in a semi off-grid situation. I have 3ph 240V AC and exporting via L1 phase at decent (almost 2x power "cost to buy" feed-in tariff). In order to maximise my power exports, I will remove all internal home loads from that phase and put on L2/L3. Those phases will go off-grid when a home 6kwh battery is fully charged). Once the home battery drains to 20% SoC I intend to provide back-up/boost from the car's battery. 35x solar PV panels on a flat shed roof will maintain power for the home battery but here comes my big decision: I have a choice to go with a 48V 5kw single phase off-grid inverter - these are prolifically available and I can even get two (one for each phase) giving me some redundancy OR I can opt for a 10kw inverter which can take up to 200V input power, hence this inverter will be able to take power direct from my EV. However this inverter is a bit of a one off and not popular brand. The problem with using the 48V battery and inverter is the need for additional kit: DC-DC converter (some more cost and losses).

If I am to go with the large capacity 200V inverter, two phases will be joined as one while off-grid and revert to individual phases in the event of grid fall-back.

My question is:

Do I stay with conventional 48V off-grid inverter and just add the extra kit or will I be better with the 200V inverter.

Any comments appreciated.

[Sunking]

Note to those considering a pure battery EV: Do not top it off every night. It will have a negative impact on your battery life. Instead, you should wait for your EV's battery to reach 10%-20% state of charge, then fill it up to 90%..

Complete BS. OK to charge to 90%, but there is no need to go down to 10 to 20% before recharge. You charge every opportunity you get. Some EV's like Tesla you are better off to plug in just about any time you are not driving.

Not much else you had to say holds water either.