Connecting a V2L car to a house as a battery.

[EVsince2016]

Ok, I know the difference between V2G and V2L.

You cannot connect a car with V2L to the house power supply because it cannot sych with the phase of the grid and an explosive outcome will result.

Would it instead be possible to connect via a DC convertor to a solar DC invertor instead to power the house?

Surely there must be a way!

 

[Gomev]

I was thinking similar things.

A house battery has a battery and an inverter and can run the house within the limits of the inverter, so why not a V2L. The Inverter task has already been done to provide the AC for the V2L, so surely we are at the same point that the DC comes out of the home battery inverter. Just need the magic bit that feeds the house from there ?????????? Total layman's logic.

 

[EVsince2016]

Looking at it, you'd need an AC to DC inverter first then any V2L load could connect!

Someone needs to design & make the kit!

 

[JohnInFrance]

Ok, I know the difference between V2G and V2L.

You cannot connect a car with V2L to the house power supply because it cannot sych with the phase of the grid and an explosive outcome will result.

Would it instead be possible to connect via a DC convertor to a solar DC invertor instead to power the house?

Surely there must be a way!

There is certainly a way to do this if you have the correct kit - @PAULinTHAILAND has posted a video of how he achieved it on his setup here some months back - the search box on the top right is your friend here.

 

[Gomev]

Looking at it, you'd need an AC to DC inverter first then any V2L load could connect!

Someone needs to design & make the kit!

I'm confused...easily done....why would you need an AC to DC inverter, the car has already done the DC to AC to make AC available for the V2L, in the same way as a house battery DC is converted by the inverter from DC to AC ?

 

[EVsince2016]

You cannot connect the AC output from the car to the AC of a house as the power would be out of sync with the grid. House invertors from solar are grid sychronised but those on a car cannot be as they're isolated. You can easily DC link a car (LEAF) via an invertor but cannot AC link due to synching issues unless going back to DC then AC.

 

[JohnInFrance]

I'm confused...easily done....why would you need an AC to DC inverter, the car has already done the DC to AC to make AC available for the V2L, in the same way as a house battery DC is converted by the inverter from DC to AC ?

Because, as you rightly pointed out in your first post, the AC from the V2L is not phased to the house, thus in the example given where a house had batteries, the input to the inverter is DC and the inverter matches that DC into an AC source phased to the house, thus you'd need to feed into that in DC as well. But, Paul has done this somehow, so all the info in in a video in his post.

 

[BugEyed]

A number of reasons:

• the AC produced by the car has a "dirty" wave form and is likely out of phase with the mains
• People input the DC through their solar panel inverter (if they have a spare string). Whilst this can work it doesn't balance the load so may draw to much or little

@PAULinTHAILAND has an inverter with twin AC inputs that's designed for switching between inputs, something that's rarer in the UK. It appears able to run from both inputs concurrently matching them via an AC to DC then back to AC conversion. So in principle the same thing.

 

[PAULinTHAILAND]

@PAULinTHAILAND has an inverter with twin AC inputs that's designed for switching between inputs, something that's rarer in the UK. It appears able to run from both inputs concurrently matching them via an AC to DC then back to AC conversion. So in principle the same thing.

My inverters have a single AC input I just use a ATS to be able to switch between Grid power input and a secondary AC source like V2L

 

[Gomev]

My inverters have a single AC input I just use a ATS to be able to switch between Grid power input and a secondary AC source like V2L

So using the ATS, it basically switches between grid or other source. i.e. either one or the other but not combined, without the need to match phases, and as you said in your final sentence the 'other' source' could be V2L.

 

[PAULinTHAILAND]

So using the ATS, it basically switches between grid or other source. i.e. either one or the other but not combined, without the need to match phases, and as you said in your final sentence the 'other' source' could be V2L.

I have my ATS set with the priority input as my backup solar system. V2L would be the priority and when the ATS senses a drop in voltage it would switch over to Grid. So if you set the V2L to a max of 50% of the car battery, when it reached 50% it would shut off supplying power from the car and the ATS would switch to grid power.

The ATS supplies either one or the other but not both at the same time.

 

[adamback]

As I understand, a grid-tied inverter relies on the gridsync. I don’t think the MG AC output can provide that.
Right now I’m setting up a solarsystem that is grid-connected but can go off-grid.
I will connect an ATM on the AC input. But the MG will not supply a useable “earth. My electrician have installed and measured a ground point for me.

 

[Obsidien]

Hello,

These all seems very overkill.

For now, V2L output AC 220V.


I was wondering : which voltage does a solar hybrid inverter tolerate as solar input ?
(check Aliexpress here : first search item for solar inverter give 500V max solar input...)

So, if solar inverter tolerate 220V, you just have to convert V2L output from AC to DC, so AC 220V to DC 220V (and solar inverter will ondulate this DC signal to an AC signal synchronized to main grid).

Convert from AC to DC is just based on an heavy diode bridge rectifier (let's 50A to be wide).
(check Aliexpress here : KBPC5010 rectifier is 5€ ... by 5 !).

Perhaps a simple way to an usable solution ?

 

[Elec Car Aust]

Various different ways to do it, Depends on your budget, current house infrastructure/wiring, use case, type of EV you have etc.etc. Really is a horses for courses.

 

[BugEyed]

Perhaps a simple way to an usable solution ?

It's very unlikely that a solar inverter would tolerate an unsmoothed bridge rectified input. You could smooth the output but that would be at extra cost and further loss of efficiency.

The car battery is DC so using the car's inverter to convert to AC then back to DC in your rectifier then back to AC in a solar inverter seems to be a lot of steps introducing lots of losses and potential for things to go wrong.

I'd suggest that you wait for a proper V2H solution such as when Indra offer a CCS option for their system.

 

[Obsidien]

I agree.
It was just my penny for users who wants to simulate V2H with their MG.

IMHO, V2L is good for home supply only in case of main grid failure (that's my case).
And so, a "simple" input-inverting main switch is good&secure enough.

 

[adamback]

I have my ATS set with the priority input as my backup solar system. V2L would be the priority and when the ATS senses a drop in voltage it would switch over to Grid. So if you set the V2L to a max of 50% of the car battery, when it reached 50% it would shut off supplying power from the car and the ATS would switch to grid power.

The ATS supplies either one or the other but not both at the same time.

I have seen the voltage dropping on load, 218-220v. Has this given you any problems? What is the maximum load you pulled from your MG?

 

[AusAeroDave]

Can someone either confirm this is possible or shred my idea to bits....

V2L from a car like an MG4 is 220VAC - 3200W. My solar inverter has two string connections allowing a combined 640VDC input, so roughly 320VDC for each string (confirmed with the manual).
Could we then convert the output of the V2L to DC (using a voltage regulator to smooth it out) and connect it to a string using a PLC or DC to DC Automatic Transfer Switch- so when solar voltage drops below 50VDC, the PLC/ATS would then allow the DC converted V2L to feed that string. The Solar Inverter would then treat this input (into the second string) no different from having the sun shine, except the Voltage is being sourced from the car rather than the panels. This alleviates the need to match phases and provides simultaneous grid and V2L input to the house.
Of course we would need to design a PLC or source a DC-DC ATS to connect both the cars V2L and Solar DC input to the same string simultaneously.

@PAULinTHAILAND

Thoughts????????

 

[Coulomb]

Could we then convert the output of the V2L to DC (using a voltage regulator to smooth it out) and connect it to a string using a PLC - so when solar voltage drops below 50VDC, the PLC would then allow the DC converted V2L to feed that string.

Drops below 50 VDC? Oh I see, if over 50 V, there is no need to use power from the car, as it's presumably day time. But then you have the problem of potentially turning the panels into giant infra-red LEDs. You can solve that by disconnecting the panels, but that requires a moderately expensive DC rated contactor or relay.

This is a common idea, but there are problems. Firstly, converting AC to DC, especially single phase, is not easy at high power levels. Sure you can just use a bridge rectifier and capacitor, but then the power factor is very poor, with current flowing only near the peaks of the sine waves. The peak current is therefore very high (10x to 100x the RMS current), and this causes heating in the cables. You would have to reduce the power by 10x or 100x to prevent the V2L system from exceeding rated current, and the initial turn-on would have to be managed carefully.

The proper way to do this is with a boost converter, commonly known as a Power Factor Correction circuit. But these are expensive and not common off the shelf.

Then there is the problem that the inverter is expecting a solar panel, with a very soft voltage versus current curve. Pure DC out of this sort of system has a very sharp curve. You can soften the curve by adding resistance, but this wastes power, and the resistor would have to be enormous.

There is the safety problem: high power, high voltage DC is dangerous; you really don't want home-made gear dealing with this.

Finally, there is the problem of keeping the car in V2L mode for long periods of time.

Overall, it's a neat idea, but the technical details make it impractical.

 

[DaevM]

Break before make switch using either grid or V2L, so no issues with syncing the two up? Manual switch over, keeping it simply controllable. (Although useable earth could be an issue - keep earth connected in switch ? )
How obvious is it I really have no idea what I'm talking about? Qualified electrician too.