Is my idea crazy or should I pursue it further?

[tsedge]

My reason for mentioning the charge speed is because this is a factor for me in thinking about getting extra batteries for the house.

We have 9.5kwh and now have a heat pump so would like more as it seems to run out in the evening when the weather is cold.

Yep, makes sense. I am not currently thinking of a heat pump because of their huge electricity requirements.

As we only have five hours of cheap electricity we can only get about 15kwh in that time. If you've got a car with 50kWh you might not be able to put that much in and out in a single day.

I should be able to get 6.4kW in the car (allowing for losses) x the number of low rate hours. With 6 hours
that would be 38.8kWh each night.

Perhaps you could build up the charge over several days and then discharge a lot when needed.

Exactly and the car could be a huge emergency battery in a power cut, lasting days.

One answer to this issue might be a V2H DC connector to the car, once those get more affordable. At the moment I think Sigenergy do one.

You'd probably want a two-way connection to the car after all, so you don't have to keep switching round from the import connector to the output connector.

Yes, this is good thinking.

 

[T1 Terry]

Yep, makes sense. I am not currently thinking of a heat pump because of their huge electricity requirements.

I should be able to get 6.4kW in the car (allowing for losses) x the number of low rate hours. With 6 hours
that would be 38.8kWh each night.

Exactly and the car could be a huge emergency battery in a power cut, lasting days.

Yes, this is good thinking.

An Aussie company is producing a 2 way V2X unit right here in South Australia, I've put the link up on a few threads on the forum and I don't want to look like I'm pushing the product or endorsing it, just saying that there is a product out there.

T1 Terry

 

[MG Clive]

An Aussie company is producing a 2 way V2X unit right here in South Australia, I've put the link up on a few threads on the forum and I don't want to look like I'm pushing the product or endorsing it, just saying that there is a product out there.

It'll probably be no use for us in the UK, but feel free to post the link again @T1 Terry

 

[Everest]

What have I missed or not taken into account here?

1) Losses. Not just the inverter conversion losses, but the V2L operation will consume (from various research I did on exactly your proposal) around 250W quiescent usage for the vehicle's electronics. That's no big deal when you're powering your kettle or oven. But when your house is ticking along at (say 300-400W) then that reduces your efficiency to around 50%.

2) Unlike a G98/G99 compliant hybrid inverter, the V2L cannot be grid tied, so you will need to switch your house from grid power to EV power via a changeover switch, resulting in brief power cut = reset all those clocks again.

3) When operating the house from V2L you will need to have installed TT earthing arrangement and suitable RCD protection.

4) Max of 7kW should be do-able, but if you bust that limit the vehicle will cut off your power. Remember that inductive loads such as fridge-freezers will draw 5x to 10x their rated power briefly on start up.

Has anyone done exactly this (as opposed to taking a battery out of an old EV)?

Not an old EV, but I assume you've read @Stageshoot's powering of his house from his MG4
V2L Test. 7kW output...

(oh yes, I see you've contributed on that thread already)

 

[tsedge]

1) Losses. Not just the inverter conversion losses, but the V2L operation will consume (from various research I did on exactly your proposal) around 250W quiescent usage for the vehicle's electronics. That's no big deal when you're powering your kettle or oven. But when your house is ticking along at (say 300-400W) then that reduces your efficiency to around 50%.

That's true, although pulling fuses in the car will probably reduce that load a fair bit. I think these losses will be outweighed by the huge capacity and potential to store lots of energy in the car pack.

2) Unlike a G98/G99 compliant hybrid inverter, the V2L cannot be grid tied, so you will need to switch your house from grid power to EV power via a changeover switch, resulting in brief power cut = reset all those clocks again.

My understanding is it can be grid tied using technology such as that mentioned above: eg via Sigenergy's products, which include a module that is specifically designed to integrate an external battery store via V2L so you don't require a home battery.

Obviously this does have a cost for that module/gateway, but it avoids buying battery modules too.

3) When operating the house from V2L you will need to have installed TT earthing arrangement and suitable RCD protection.

Again, not as I understand it using the approach outlined above. I might be completely confused and wrong, of course, that's possible.

4) Max of 7kW should be do-able, but if you bust that limit the vehicle will cut off your power. Remember that inductive loads such as fridge-freezers will draw 5x to 10x their rated power briefly on start up.

Again, should all be configurable an manageable via the gateway that I use so that any extra demand will come via the grid. Unless during a power outage, in which case I'd keep the load low (and/or automatically have some appliances disabled).

 

[Everest]

My understanding is it can be grid tied using technology such as that mentioned above: eg via Sigenergy's products, which include a module that is specifically designed to DC integrate an external battery store so you don't require a home battery.

Obviously this does have a cost for that module/gateway, but it avoids buying battery modules too

I thought that bi-directional V2H capable chargers like theirs currently cost around £5K and require an EV such as the ID.4 that provides bi-directional DC charging

Regular V2L systems (e.g. as found in Kia / Hyundai and MG + some Renault) can't be grid tied. You can, of course, use the vehicle's V2L to trickle charge an existing 48V-based home battery system so that you can use the storage capacity of the EV to supplement your home battery capacity - others on here have done that.

 

[Rolfe]

Re that last, I wish I knew how.

 

[Bam Bam]

Yep, makes sense. I am not currently thinking of a heat pump because of their huge electricity requirements.

I've been very impressed with our Heat Pump in the first month and a half.

In November we got ~500% efficiency. It doesn't take more than about 1200w at a time, despite having a 5kw output.

The efficiency seems to drop when the weather is cold, but still around 360% efficiency.

I should be able to get 6.4kW in the car (allowing for losses) x the number of low rate hours. With 6 hours
that would be 38.8kWh each night.

Exactly and the car could be a huge emergency battery in a power cut, lasting days.

A nice service.

 

[tsedge]

I thought that bi-directional V2H capable chargers like theirs currently cost around £5K and require an EV such as the ID.4 that provides bi-directional DC charging

Ah.... is that the bit I missed? I need to do more research then. Although it just means getting an MOT-failure car of the right capability (I believe the Ioniqs support this).

Regular V2L systems (e.g. as found in Kia / Hyundai and MG + some Renault) can't be grid tied. You can, of course, use the vehicle's V2L to trickle charge an existing 48V-based home battery system so that you can use the storage capacity of the EV to supplement your home battery capacity - others on here have done that.

That's an interesting option. Thanks for mentioning it.

 

[Everest]

Although it just means getting an MOT-failure car of the right capability (I believe the Ioniqs support this).

I think the Ioniq 5 is only V2L, same as MG4 but with 3.6kW output. Ioniq 7 is rumoured to support V2H, but it will be a while until they're MOT failures of those.

 

[GaryMG4]

I don't know if the Chademo Delta V2H is available in the UK, just add your Leaf/eNV200.

 

[Bam Bam]

I don't know if the Chademo Delta V2H is available in the UK, just add your Leaf/eNV200.

This guy runs his house off an eNV200 van, but it might have been a trial...

 

[GaryMG4]

This guy runs his house off an eNV200 van, but it might have been a trial...

There was a trial 4/5 years ago, you could lease a new Leaf and get the charger installed for free, all you had to do was plug the car in before 18:00 a certain number of nights each month and they would pull from the car to the grid and then put it back for free.

 

[Evergreen]

Hi,

I've been learning more about solar/battery setups and it seems to me that a great DIY way to maximise savings would be to directly use a cheap old EV as battery storage and home power backup.

The car wouldn't even need an MOT, so long as it had V2L and a decent battery capacity left. This would seem to be far cheaper than buying a brand new home battery and also much less work than removing the battery from the EV and installing it on the outside of the house in a custom side building or shed.

The main drawback would seem to be the space that a whole car would permanently take up, but assuming that was available, it seems like a good solution.

What have I missed or not taken into account here?
Has anyone done exactly this (as opposed to taking a battery out of an old EV)?

Thanks in advance for your comments, I am still at the beginning of learning about all of this.

Have you taken account the cost of the charging and inverter systems? Do you have the skill set to make it all work safely?

 

[tsedge]

Have you taken account the cost of the charging and inverter systems?

That's part of the exploration.

Do you have the skill set to make it all work safely?

I will be paying an electrician if this goes ahead.

 

[T1 Terry]

1) Losses. Not just the inverter conversion losses, but the V2L operation will consume (from various research I did on exactly your proposal) around 250W quiescent usage for the vehicle's electronics. That's no big deal when you're powering your kettle or oven. But when your house is ticking along at (say 300-400W) then that reduces your efficiency to around 50%.

2) Unlike a G98/G99 compliant hybrid inverter, the V2L cannot be grid tied, so you will need to switch your house from grid power to EV power via a changeover switch, resulting in brief power cut = reset all those clocks again.

3) When operating the house from V2L you will need to have installed TT earthing arrangement and suitable RCD protection.

4) Max of 7kW should be do-able, but if you bust that limit the vehicle will cut off your power. Remember that inductive loads such as fridge-freezers will draw 5x to 10x their rated power briefly on start up.



Not an old EV, but I assume you've read @Stageshoot's powering of his house from his MG4
V2L Test. 7kW output...

(oh yes, I see you've contributed on that thread already)

A few things the V2X looks after there. It is an interface between your house battery and EV battery or grid connection. It is not intended to feed back into the grid, it is to island your house from the grid and only use grid assist when the load exceeds the V2L capability.

The next bit is assumption on my part, but after reading a lit about the units, this is what I assume is possible. It is basically how a Victron Multiplus and Quattro work, the Quattro can have both the V2L and a generator or mains wired into it at the same time, and depending on how it is programmed, can switch between each supply and a house battery, as required.
The max draw from the EV is programmable, it can use either the mains or in the case of the Quattro, the house battery, as a load assist, seamlessly integrating the grid sinewave via the inverter drawing from the house battery, using the mains to replace any requirement in the house battery as it changes back to a battery charger once the overload is covered, then dropping the mains when no longer required.
The advantage of the V2X, it can be programmed to sense when the house battery is fully charged via the solar, then rather than selling to the grid if the payment is less than the supply, it will store that back in the EV battery for later use when needed.

All happens without operator intervention, the Victron gear is so fast, unless you have a back up generator that it needs to start up, you won't know it had assisted at all. It has a 100% overload capacity, so a 5 kVA inverter can carry a 10 kVA load while it determines if the mains voltage and frequency is stable, if not, the start up the generator, bring it up to speed to check the same voltage and frequency requirements, switches from mains supply to generator supply, then slowly adds the load to allow it to both warm up and adjust to the load.

An incredibly intelligent UPS (Uninterrupted Power Supply) that will only get better once AI is developed to handle these functions and more, like selecting non essential loads that it can put in standby mode, delay high load start ups until the system is capable of accepting them ..... and who knows what else.

The big battery packs over here can do that already, plus voltage a frequency stabilisation, no need for spinning momentum generation to absorb shock loads, they don't voltage and frequency follow, they voltage a frequency generate is required, so fast it is seamless ....
South Australia has used this ability a number of times already over the last few yrs, keeping the grid stable when the other states linked via DC interconnector, drop out because they had issues with their grid stability .....

I only added that last bit to show it's not a fantasy, it has been a reality for a number of yrs ..... It has been available at house level for yrs as well, and it continues to improve ...

T1 Terry

 

[Coulomb]

A few things the V2X looks after there. It is an interface between your house battery and EV battery or grid connection.

That's V2H, not the other values for X.

It is not intended to feed back into the grid,

V2G is. Vehicle to Grid.

 

[T1 Terry]

@Coulomb, the manufacturer in South Aust calls it a V2X, I'm not about to argue with them or Kryten ..... for fear I'd be called a "Smeghead" Australian-made bidirectional (V2X) EV charger hits the market

T1 Terry

 

[johnb80]

tsedge, I'm late to the party here, what youre talking about is essentially what I have done but using slightly different directions in places.

You can certainly use scrapped cars as a source of batteries, do your research to find the chemistry etc. The cost of batteries has reduced considerably over the last few years and brand new EVE LifeP04 cells are now £70 each nominally 1kWh each so a 16 kWh battery can be built for £1120. There is currently a 10% off offer so that reduces it further to £1008. Alternatively, there are cheaper cells to achieve the same capacity for £790.

You would need a battery management system, typically Seplos or JK circa £190.

Finally you need an inverter, I use Victron Multiplus II inverter. The Multiplus II was designed for exactly this sort of application, it has charging facilities built in, it can be grid tied (it sits there supplying all of your load from batteries, if load exceeds the capability or the batteries are flat it will supplement your supply from the mains). You literally from a user point of view dont know it's there. The multiplus II comes in various capacities, 3, 5 8, 10 kW etc. The 8kw one is around £1500 and will comfortably stand the shock loads of startup etc.

Many battery / solar installations have inverters that are too small, usually 3.15kW, it because of the regulations. The 3.15kW requires a G98 application to your local DNO (Distribution Network Operator), G98 really just informs them that a small grid tied inverter is in place. Above 3.15kW you need to do a G99 application, the DNO can grant or decline permission. It sounds daunting, when I did mine, I called them up and had a chat about my plans, they were quite happy and asked that I limit the export from the Multiplus II to 3kW maximum, easily achieved in a menu setting. Once up and running, armed with data from the Multiplus II they removed that limitation.

This is typical consumption for me, as you can see it's pretty much all off peak at 7p kWh.

A 32kWh 8kW capacity power wall can be made and installed for less than £4000 which is probably not too far off the scrapped EV pricing after you consider inverter/charger needed etc, it would also be a much nicer setup. In terms of payback / break even peak rate = 26.46p off peak 7p saving 19.46p kWh. Potential saving from 28kWh battery = £5.45 per day. 734 days would achieve break even. With a little bit of programming with home assistant you could sell excess energy back to the grid at 15p kWh which in turn would reduce the break even point even more. A system I built for my son achieved payback in 15 months!

Thats my 10c I know not everyone agrees with me and I have even been christened 'some bloke in Lincolnshire' in some quarters, however, all what I have stated above I have installed in my home and it has been working for over 4 years without issue. With minimal cost you can attach your MG to the system to supply additional battery capacity as I did on Christmas day, 40kWh out of the MG, the rest from house batteries and it ran heatpumps, cooker etc all day on off peak energy.

My system is housed in a little 'toolshed'

Inside is the Multiplus II, the BMS (yellow panel) and below are the 16 cells.

 

[T1 Terry]

Just a note to add to @johnb80 post, the Victron capacities are in VA, not watts, so a 3000VA is around 2500 watts with a correction factor of 1, like a toaster or other heater element type load, once you get into the other type loads, including anything with a capacitor, I'm not even going to attempt to come up with power efficiency factors.

The Victron units can be paralleled to increase capacity, but better still, is a load activated stepped turn on that feeds a second inverter into the AC supply side of the primary inverter, then turned off when no longer required ..... all programmable, not smoke and mirrors, but that Arthur C Clarke coined term sometimes comes to mind

Hopefully, if anyone wants to know, I can still remember how to do if asked .....

The last item, if @johnb80 is referring to the Tesla Powerwall ..... I'd think twice about using one, they are built with cells containing cobalt, so susceptible to thermal runaway fire risk, LFP, LTO and Na+ suffer no such risk, last more cycles in a house battery load situation, and the salvage EV comes with all the battery monitoring, safety battery enclosure and the MG LFP variants output 220 VAC 50 Hz at up to 7kW (7,000W divided by 220V = 31.8 amps) so make sure you use 5 AWG multi-fine strand conductor, 2 core and earth orange flex lead, to carry the load from the EV to the house power entry .... your call as to adding a plug and wall socket to make it a plug in appliance if it makes all concerned feel happier about it

T1 Terry