I would like to use the Battery of my BYD Seal (85kwh, max output over VTL: 2kw) to partly power my home at night, while charging it back up during the day.
Is it possible to plug an AC-DC inverter (2kw) to the VTL power socket and connect the output side with an unused Solar string input of my solar inverter (Huawei Sun200 KTL20-M0).
My theory is it would simulate a constant supply of 2kw solar power during the night.
In the morning, I would manually switch the VTL plug with the EV charger and back again in the evening.
Could that work? Is there any risk of damaging to my car or solar inverter or possibly burn down my home?
That is a unique idea. Technically, it would be possible to convert the AC V2L output to high-voltage DC, but you would need an isolated converter so there is no risk of earth leakage. Ideally, you would want to supply around 250V DC at 8 to 9A
Have you found a converter to do the job?
Thanks for the reply. I just got the converter i ordered. Its a MZMW SK-2000-220. Converts 220V AC 15A to 220V DC 9.1A. I think that should be what you recommended as well, right?
At the moment I am waiting for an electrician to come do the wiring (could do it myself, but I think it’s better to let a professional do it)
Will let you know the results in a view day.
Note: just to avoid confusion, I live in Thailand. The standard voltage here is 220V.
Is this the one you ordered? I’ll be very interested to hear if it works. There could be an issue with the earthing as the V2L output is a “protected” supply, which will trip off if any loss (earth leakage) is detected inside the converter.
Yes, that’s exactly the one I got. Guess will just have to try it to find out if it works. There is a YouTuber in Thailand who has the same car and successfully connected it to his solar inverter… but he has a single phase hybrid inverter with batteries and connected the car to the AC side of the Inverter, replacing grid power.
I have a 3 phase on grid inverter without batteries and intend to connect it to one of 4 DC string ports that is currently unused. So it’s a different type of connection and a different setup. But the car is the same and seems to handle the job.
The reason I’m doing this are new meters the developer of my gated community installed against the will of the house owners. Unlike the old ones, they don’t show exports, and were installed with the intent to stop people from sharing solar power. We got a private microgrid with only one common State Grid access over a one way transformer. So we legally were able to share solar power inside the community since I and later 5 others installed solar systems 2 years ago.
One Day the developer showed up and demanded me to remove my solar cells. When I refused to do so, he installed new meters. He claimed solar producers make others pay more, so he has to stop it. I tried to explain to him the numbers clearly show they profited from it. In Thailand, power costs almost half during the night of what it costs during daytime, so trading excess solar power for nighttime units means getting power for half the price. But he didn’t listen to me.
So now i about 1 MWh of my solar power is either lost (zero export) or not compensated for every month, and I am looking to reduce my night time usage without having to invest in batteries.,
Today I connected the Converter to the Solar inverter string input to test if it works. (used power from the normal plug instead of the car).
It actually did work. The Inverter sowed 1.9kw solar power (at night).
But there was a problem with the converter starting to turn on and off frequently. Increasing the power used by the house seems to have fixed it, but it would kind of go against the whole point of the experiment if I have to increase Power usage in order for it to work.
Any Idea what might cause that issue? The converter makes a beep sound about every 7 seconds, power output goes to 0 amps, then beeps again, power goes up again then repeats the hole thing. When I increase the usage, it still beeps, but power does not go off.
Unfortunately, I didn’t get a manual for the converter and can’t find one online.
There is a connector for start and stop signal… but don’t know what to do with it.
It might be the grid supply voltage is too high. When you use more power in the house it will reduce the voltage (this is normal). Can you measure the grid voltage?
I suspect you will not have this problem when using power from V2L since the voltage is only 220V. Have you tried the V2L with the converter?
Not Yet… I’m waiting for my electrician. he wanted to set up a magnetic switch box first and took the converter with him. Don’t really understand why, but anyway… will take a view days. Will let you know the results once I have it connected to VTL.
Happy new year.
Today we connected the car to the inverter.
As you predicted the car turned off after about 5 minutes (guess it was the 5 minutes the inverter needed to start up)
It showed an error message and just turned off
Do you think there is something about the connection that can be done to fix this? Or by adjusting voltage and amps of the AC/DC converter?
The way it is connected now is like this:
Update: Today I managed to get it to work for almost 3 hours before it turned off.
I started to import VTL just before the inverter turned off at 6pm, and it kept running stable till the car turned off again at 9pm.
I think I’m somehow getting closer to solve the problem without even knowing what causes it 
Very interesting progress. That looks like a nice professional setup.
Did you tweak any of the settings on the converter to get it to work for longer?
I believe the V2L output will automatically disconnect after 3 hours, regardless of the load. I might be wrong, but I recall this was done by BYD to ensure the battery was not discharged too far?
I experimented with different tweaks (lower-higher voltage, lower-higher amps) for a couple of days now, and today i seem to have found the right settings. It is working since over 4 hours now and seems to do just fine.
I drastically reduced the amount of amps by about 5 turns while leaving the voltage where it was originally (i guess 220v, but my converter does not have a display, so I can’t tell how much it is exactly)
I just get 1 KW, but it’s stable. If it runs all night without problems, tomorrow I will try to gradually increase the amps and see how much i can get before it fails again.
update:
It did run all night at constantly 1KW.
I purchased an other Power supply, but this time 1500w and with display to see the voltage and the amps.
Since I installed it, the system runs smooth at near 1.5 KW all night.
The battery of the car is used down to around 80% for one night and recharged again within 3 to 4 hours during the day.
The only thing missing is an automatic switch between the charger and the VTL cable. Switching manually every morning and evening is a bit of a hustle.
Any Idea how this could be done? I know nothing about how those cables… and they are too expensive to just cut them and see what’s inside.
It’s kind of funny it works, since Sun2000 M0 is advertised as not being compatible with batteries, while VTL is understood to not being able to do what VTH or VTG does. Looks like it’s actually quite easy to do all of that.
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Haha, that’s amazing. It worked because you tricked the Huawei inverter. It does not know the supply is from an EV; it only sees a DC supply from a solar input at the correct voltage.
What is the new power supply exactly. Is it the same brand but just a smaller 1500w unit?
The automatic switch between the charger and V2L will not be easy, but it would be technically possible. You would need a four-pole contactor with 2NO/2NC. This would switch the AC connection between the charger and V2L. However, you would also need to switch the PP pin to earth link via the inline resistor. (The resistor is needed to engage V2L mode - https://global.discourse-cdn.com/cleanenergyreviews/original/2X/0/054129d90a6df2481ed01e9e1b896a4ad2257fde.jpeg)
Yes, its the same brand, but the SE instead of the SK version. (comes with display that shows voltage and amps).
Thanks a lot for the advice regarding the cable. I was searching for this information now for a long time without success. Without your help, I would have given up already.
So again. Thank you.
I will do as you recommended and try to install a four pole contactor to switch between Charger and VTL.
I assume the Type 2 cable in the image you sent me is connected with a single phase charger, right? But why is the PP (proximity pilot) not connected? Is it just a secondary ground for CP?
And the resistor has to be 110 Ohms with 0.1 tolerance, right?
Off Topic:
I recently had a look at the specs of the Tesla model 3 and was a bit surprised to see its battery is rated at 1500 recharge cycles. That means using it as a solar battery on a daily basis would make it last less than 5 years.
The BYD Seal is rated at 3000+ to 5000 cycles (depending on the source). So the battery will probably still be alive after the car dies of old age.
Didn’t know that before I bought the car.
No worries. It’s been very interesting following your progress. Yes, single-phase charger. I don’t think any BYD vehicles have 3-phase charging.
With BYD, the PP pin is not required for V2L. I’m not sure why, but that’s just how they determine whether the V2L adapter is connected.
The resistor value is 2k Ohms. (I also measured it to double check) Sorry, the colours in the photo are a little hard to judge. You can see the full details here… BYD Atto 3 V2L load testing - Vehicle-to-load power output
Very interesting Solution, have the same Idea in my mind since a while. Most likely I will buy a BYD Atto 3 and trying to find a solution how to hook up to my Solar System to use the Battery as back up. Have also a 3 phase Huawei Hybrid Inverter, but a 10 kw only and both MPPT Ports are used.
May I ask you where are you living in Thailand?
Hi, thanks for the interest. Using both MPPT ports is no problem. Unlike I wrote in the beginning i actually have 4 solar strings connected. So there was no free port, and it’s not needed. You don’t want to have your car permanently connected once the sun goes up anyway. I have a magnetic switch with a timer installed that switches between the port connection between a solar string and the converter (the one connected to the VTL cable) output line. But just now while writing I realized it would make more sense to use a light sensor than a timer. Will change it tomorrow
I live in Hua Hin. You live in Thailand as well?
Thanks for the response. Yes, living in Thailand as well and not far from you in Sam Roi Yot. May be I can come for a visit to your home to meet you and have a look on your set up? Would be great.
Yes, sure. You can add me on Line. my ID: is alain_ok