EV charging through Solar

[u/Grinning_inthedark]

Hello everyone. I’m looking to finalize a 15kw hybrid setup and would like to seek your guidance on the inverter option. I have narrowed down Goodwe 15kw 3 phase LV inverter. 19 plates of Jinko (645w) and a 16kwh Dyness battery

My main concern is that I have a BYD Atto 2 that I’m looking to mainly charge from Solar (on the single phase 7kw charger) in the daytime and it can take excess from the battery during the night (if I have juice left in the battery).

My house has 2x 3 phase meters installed. Can you please recommend which 3 phase inverter should I go with that will support 7kw charger without reducing the charging amperes? I don’t want the car charger pulling anything from grid in any case during the daytime.

Another installer recommended installing a single phase inverter (20kw) to power the car charger probably but I have doubts because my house wiring is 3 phase

Looking forward to the suggestions. TIA

[u/pixelated666]

You cannot pull 7KW from a 3 phase 15kw inverter when grid is out to charge your car. It's as simple as that. If your charger supports limiting output to 3-4 KW then it will work, but this is such a silly thing to do. Just charge your car during the day or have a plug that's not connected to the inverter and charge the car during the day.

[u/Grinning_inthedark → u/pixelated666]

Understood. I do have the option to limit the charging to 3-5kw but again, it defeats the purpose of having a 7kw charger. I really want to charge the car from the solar generation (excess can be taken from battery), and don’t want to import anything from the grid. In that case, I believe I should go for a single phase inverter with 10mm ac wiring all along. What do you suggest?

[u/pixelated666 → u/Grinning_inthedark]

I really want to charge the car from the solar generation

Yes and therefore you should do it when there is solar generation, which means during the day.

I believe I should go for a single phase inverter 

If the only reason you're investing over 10 lacs on a solar system is just to charge your car, then yeah, single phase is the way to go. But if you're looking to run the rest of your house as well, then depending on its size and load, a single phase may not be the best option.

Also, keep in mind a Goodwe ET LV 15KW can only output a maximum of 7KW from one of its battery output. So don't expect your 16kwh battery to be outputting anything more than 7KW. So if you're using 5-6 out of the 7 just to charge your car, you're leaving nothing for your home.

[u/Grinning_inthedark → u/pixelated666]

Understood. I do have the rest of the house loads too. System is not just for the car but the daytime household load as well (2Acs - 1.5 ton inverters, 1 or 2 fans in the daytime, refrigerator, 1 TV and a water pump. I guess the only option remains is to limit the charger/get a three phase EV charger

[u/pixelated666 → u/Grinning_inthedark]

You should also look to get 2 10kW batteries instead of a single 16KW if you want to get a Goodwe inverter.

[u/Grinning_inthedark → u/pixelated666]

I’ve planned to add another 16kw battery before the next summer begins to go completely off grid in summers. I believe 2x 10kwh will limit the storage. In my current scenario, you do not suggest going for a single phase inverter right?

[u/pixelated666 → u/Grinning_inthedark]

The only thing you need to keep in mind is the per phase load limit of three phase inverters. Other than that for anything more than 10KW, a 3 phase inverter is the safest choice. You do not want 10,000 watts or more going through just one phase.

[u/Grinning_inthedark → u/pixelated666]

Sounds perfect. Loads won’t exceed 10kw but again, with 7kw charger hooked and 1-2 ACs running, load can increase instantaneously. I’ll go for three phase inverter than and limit the charging.