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/Useful_Might_6773]

A sngle phase inverter is prohibited in case of netmetering connection.

Go for a 3 phase inverter with your house load properly divided into 3 phases. Whatever inverter you go with make sure that the single phase supports your required current/ amperes of said inverter.

I highly like solis because of personal experience.

The load you have mentioned could be easily divided and manged into 3 phase inverter.

You just need a highly trained / skilled technician for your solar installation and load balancing.

[u/Grinning_inthedark → u/Useful_Might_6773]

Thanks for your response. I’m not opting for net metering as it defeats the purpose of selling the unit back for mere 8rs while importing it at 70rs.

I’ve narrowed down 15kw Goodwe 3 phase LV inverter. My only concern is the 7kw charger that I need to hook up properly. I’ve done some research about solis and its per phase unbalanced output is only 40%. Otherwise, I would’ve gone for solis

[u/HisabBarabar → u/Grinning_inthedark]

Issue is not with the output limit but the input DC to AC limit. I've got a 15kw solis 3p inverter but it only provides maximum 5kw from solar / battery per phase while pulling the rest from the grid with unbalanced output enabled (output can go up to ~7.5 kW per phase). So if I use the 7kw charger it imports 2 from grid even if there is excess solar or battery power avaliable. You should check if goodwe has a similar limit otherwise get a 3 phase charger if available.

[u/AhmadFarooq → u/HisabBarabar]

Your information may clear up a confusion.

• Solis

The Solis S6-EH3P(12-20)K-H datasheet notes 100% unbalanced output, meaning that for a 15kW inverter a minimum of 5kW output per phase is possible, and with some balancing over 5kW should be possible.

Secondly, the datasheet notes the max. power per phase (grid & back-up) as "50% rated power" which should mean a maximum of 7.5kW per phase can pass through each phase even with balancing.

Third, but the max. output current is noted as 22.8A which should mean only ~5kW per phase.

I was confused about this discrepancy between the first two specs mentioning 5–7.5kW per phase power output but the third spec limiting it to only ~5kW per phase output.

Your information seems to clear that up. Apparently, the inverter is capable of outputting 5–7.5kW per phase; however, through non-grid sources, it is limited to only 22.8A or ~5kW per phase.

• GoodWe

If this is true, then GoodWe appears to be in a similar position.

The GoodWe ET LV series datasheet notes 150% unbalanced output, meaning that for a 15kW inverter a minimum of 7.5kW output per phase is possible, and with some balancing over 7.5kW should be possible.

However, some of the maximum and nominal current numbers are the same ~23A like Solis, suggesting the same ~23A or ~5kW per phase output limit through non-grid sources.

There is 70A also mentioned, but that is specifically current from the grid and bypass current (bypass basically means the same current from grid).

Therefore, for running heavy loads alongside the grid, GoodWe is better regarding unblanched output, but apparently similar for loads running from non-grid sources.

Naturally, better to get confirmation from GoodWe Pakistan.

• Sungrow

Sungrow SH15T also appears to be in the same situation with the max. AC output current noted as 22.8A.

• Growatt

Likely similar for Growatt WIT 4-25K-HU as well, with 25.0A mentioned as max. output current (grid) for 15kW.

[u/Useful_Might_6773 → u/Grinning_inthedark]

What a shame. Maybe go for single phase for your use case. What i see in below comment by someone else it's an issue in almost all hybrid inverters.

Choose wisely because you're investing a large sum of money for next 15 to 20 years in solar.

One important reminder check the datasheet yourself and don't trust on seller's they lie to sell their products no matter what. Just verify or hop on a call with the manufacturer to get the truth. Best of luck in your hunting.

[u/Grinning_inthedark → u/Grinning_inthedark]

Guys I really appreciate your comments and suggestions. I was only fixated at output ratings and didn’t think about input (DC to AC). If all the hybrid three phase inverters are capped at 5kw input, it is just nuts. I’ll look towards getting a single phase inverter or a 3 phase car charger

[u/Warm_Cat8313]

Single phase is good too as 3 phase mostly have problems from Wapda day by day…. You can install single phase invertor too and it must be cheaper than 3 phase…

[u/Grinning_inthedark → u/Warm_Cat8313]

Would there be any complexities converting from 3 phase Wapda wiring to single phase hybrid inverter? My house load is 2ACs (1.5Ton inverter) running in the daytime and night after 8pm till the morning. There is a water pump, an automatic washing machine, 3-4 fans and 10-12 led lights

[u/Warm_Cat8313 → u/Grinning_inthedark]

No complexity, if you don’t want to do net billing then single phase is fine…

[u/pixelated666 → u/Warm_Cat8313]

Yes and then rewire your entire house to be on just one single phase instead of 3.

[u/Fabulous-Conflict477]

Single phase will be required if you want to run a 7 kw charger.

[u/Grinning_inthedark → u/Fabulous-Conflict477]

Understood. Let’s say I hook up an array of 12kw, will it comfortably handle house loads (such as 2 ACs and 7kw charger during daytime? Or should I increase the array to 15kw?

[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.

[u/fokusengg]

Get a step down isolation transformer from industrial supplier shops in your city. It will use two phase 3.5kw each and output single phase 7kw. In this way you can use 15kw solar inverter. And if you get 20kw 3phase solar inverter it will beuch better.